Kepler confirms first planet found in the habitable zone of a Sun-like star!

By Phil Plait | December 5, 2011 12:20 pm

[NOTE: I have been informed that this is NOT the first planet seen in the habitable zone of another star, but the first seen by Kepler, and moreover the first that is not a gas giant. Rather than try to correct the text below using strikethroughs, which would be confusing, I simply edited the text. I hope that’s clear!]

http://www.eso.org/public/images/eso1134b/This is pretty big news: the space-based Kepler observatory has confirmed it has found its first planet in the habitable zone of a star like the Sun! Not only that, the planet may well be similar to Earth, though that’s not clear yet.

The planet, called Kepler-22b, is about 600 light years away. The star it orbits, called simply Kepler-22, is a bit lower mass and cooler than the Sun. The planet takes about 290 days to circle the star once, and as soon as I saw that number I let out a little "yip" of surprise — that number’s perfect! Why?

Because that puts the planet inside of that star’s habitable zone, the distance where, given certain planetary conditions, liquid water can exist. It may be that life can arise where there’s no water, but we know life on Earth needs water, so if we’re looking for habitable planets it makes sense to look for the possibility of water there.

The planet is closer to its star than Earth is to the Sun — that’s why its year is shorter — but the star is cooler, compensating for that. That makes this the best candidate yet for Earth-like conditions. But is the planet like our own world?

That’s hard to say.


Kepler detects planets when they transit their star, passing directly in front of the star, blocking its light a little bit. The bigger the planet, the more light it blocks. The astronomers going over the data determined that Kepler-22b is about 2.4 times the diameter of the Earth. The problem is, that and its distance from its star are all we know. We don’t know if it’s a rocky world, a gaseous one, or what. It may not even have an atmosphere!

So we can’t say what conditions are really like on the planet. As you can see on the diagram above (click to embiggen), mass and atmosphere make a difference! Venus and Mars are both technically inside the Sun’s habitable region, but Venus’s thick atmosphere makes it hotter than an oven, and Mars’s thin air makes it colder than a freezer (if we could swap those two, though, then things would get pretty interesting in the solar system). Kepler-22b might be a paradise, or it might be the opposite. That depends in part on the planet’s gravity, and for that you need its mass.

The problem is we don’t know the planet’s mass. Kepler’s transit technique doesn’t find that; it has to be determined using very tricky observations of the planet’s gravity as it tugs on its star. Since Kepler-22b’s orbit is 290 days long, that makes this kind of observation much harder (the closer in the planet, the harder it pulls on the star, and the bigger the signal… plus you don’t have to wait as long for it to go around once). In fact, that’s why it took so long to confirm this planet’s existence — you need three transits for that! The first transit took place coincidentally just a few days after Kepler was launched in space, but the planet had to pass in front of its star a second time 290 days later to make sure the dip in starlight was real, and then a third time 290 days after that to confirm the period.

Now we might speculate that the planet is similar in composition to Earth — rock and metal and water. If so, then it has more gravity than Earth. Standing on its surface (assuming it has one) you’d weigh 2.4 times what you do on Earth! So even if it looks like Earth, it won’t be too much like it. On the other hand, if it’s made of lighter materials, the gravity could be lower. We just don’t know yet.

But that doesn’t diminish the fact that this planet exists at all! We’ve found a relatively low mass planet orbiting its star at the right distance for Earth-like conditions to arise. That’s very exciting! We’ve been closing in on this for a while now, finding lower mass planets that are too close in (though getting close to their star’s habitable zone), or bigger planets (like Jupiter) at about the right distance. This is the first confirmed planet that’s at the right distance and may have the right mass to be considered Earth-like.

Right now, as far as we know, Earth is still the only planet in the whole galaxy that has life, or even the exact right conditions for life. But what observations like this tell us is that there are more planets out there, a huge variety of them. This means the odds get better every day that — for some planets at least — the characteristics all come together to make them look an awful lot like us. The day is getting closer when we find that first planet. It’s just a matter of time, and the diligent work of astronomers like those who found Kepler-22b.

Image credits: ESO/M. Kornmesser; NASA/Ames/JPL-Caltech


Related posts:

How many habitable planets are there in the galaxy?
A boiling superEarth joins the exoplanet roster
New study: 1/3 of Sun-like stars might have terrestrial planets in their habitable zones
50 new worlds join the exoplanet list

CATEGORIZED UNDER: Astronomy, Cool stuff, Top Post

Comments (153)

  1. jason

    THis is very very cool news. I hope they are able to get more data and confirm its mass and maybe even some information about composition.

  2. Jeff

    Hi Phil, can you clarify whether the number 290 was enough to tell you that it had to be in the habitable zone, or if it would be possible that it is really close to the star and going slow, or really far from the star and going fast? I think you are saying that the numbers “felt” right for the star to be slightly cooler than our sun and also for the orbital period to be slightly lower than for Earth, but I didn’t quite get as much of an answer to your question “that number’s perfect! Why?” as I hoped. Thanks!

  3. Grimbold

    Need to point a very sensitive spectroscope at it the next time it transits so we can find out something about its atmosphere.

  4. It seems to me that gravity would not have as great an impact on the development of life than other factors such as the availability of liquid water. It would be interesting to see what life on a planet with 2.4 times the gravity would look like. Reminds me of Hal Clement’s A Mission of Gravity.

  5. Any way to find the KIC number of the star? I know, for instance, that Kepler-21 KIC 3632418 from the Pale Blue Dot project but I don’t see an entry for Kepler-22 yet.

  6. Mathias R.

    @2. Jeff: The orbital period of an object is directly correlated to the mass of the object being orbited, and the distance of the object orbiting. The further in you go, the faster the orbital period. The further out you go, the longer this gets. Period.

    As for whether the planet has an atmosphere or not, @phil: wouldn’t one be able to take a spectrum? After all, isn’t it basically the opposite way of how it was determined that Pluto has an atmosphere (however faint)? By a star transiting the disc, and measuring the absorption of light?

  7. Grimbold

    @Jeff, #2

    There is no way for a planet to be close to a star and moving slowly, or distant and moving quickly.

    The average distance from the planet to the star is determined entirely by the mass of the star and the orbital period of the planet, so that if you know the last two you can calculate the first, with no possible ambiguity. In this case we know the mass of the star by studying its spectrum and luminosity, and we’ve just measured the orbital period.

  8. Kepler detects planets when they transit their star, passing directly in front of the star, blocking its light a little bit.

    Given this requirement, it’s amazing that it can find any planets at all.

    Suppose we were to project Earth’s “shadow” (okay, “penumbra” is probably more accurate) onto a sphere 100 light years across. What percentage of this sphere would be within the “we can see Earth transit the Sun” zone?

  9. James

    Would it be 2.4 times as much gravity? Wouldn’t the increased distance from the center of the planet compensate somewhat for that?

  10. Quatguy

    The interpretation also assumes that the planet has a nearly circular orbit? Could the orbit be more eliptical with a period of 290 days and approach the sun closer in than the habital zone with only the transit portion (from our perspective) visible to us inside it? I assume this could be discounted by the observance of any effects of precession.

  11. Gwif

    What’s it going to take to answer the unknowns, like the composition of the planet?

  12. Susan Stanko

    How far is it from Earth?

  13. I was about to ask the same question as James.

    I’m not very physics inclined, but it’s not as simple as “2.4x more massive –> 2.4x as heavy on the surface,” right? If it were the same size as Earth and 2.4x as massive, then sure, but being further away from the center should have some effect — possibly a substantial one.

    For example, according to WolframAlpha, the moon is 27.2% the size of Earth yet its gravity is only 16.6% due to it being only 60% as dense comparatively.

  14. This is exciting news! I wonder if there is any way to know what the albedo is to help determine what temperatures and gases could be found there. Of course mass would be nice to know.

    My question is, if it is in fact rocky, what are the chances that a planet that big will have an active tectonic system? Could it have a molten core and still generate a magnetic shield?

  15. Jim Johnson

    This article makes me wonder: has anyone begun to make attempts at refining the Drake equation yet, using recent planetary data?

  16. Anthony

    An object 2.4* the diameter of the Earth, with density similar to Earth, would be able to hold on to hydrogen gas in its atmosphere, and would thus bear more resemblance to an inner system Uranus than the Earth.

  17. Standing on its surface (assuming it has one) you’d weigh 2.4 times what you do on Earth!

    Are you sure about that? Even though its denisty might be the same as Earth, given its radius, wouldn’t the distance from the center end up figuring in to the problem as well?

    g= GM/R^2

    EDIT: Looks like others also keyed in to the surface gravity statement.

    @Ken B (#8): Check out this answer from the Astronomy StackExchange: http://astronomy.stackexchange.com/questions/1229/what-percent-of-planets-are-in-the-position-that-they-could-be-viewed-edge-on-fr/1232#1232 Pretty cool stuff there.

  18. Ken

    the planet had to pass in front of its star a second time 290 days later to make sure the dip in starlight was real,

    I take it that they didn’t keep Kepler continuously pointed at the star, so how did they allocate telescope time to catch this second event? And are they sure it isn’t, say, a 145-day period where one transit was missed?

  19. steve l

    Is there any information on the spectrum of the star, kepler 22, published so that a guess at the metalicity of the star and thus the possible density of the planet could be made?

    The 2.4 diameter alone may not define the gravity of the planet as the density would also be key. A low density could speak to a high water content, could a planet this close to a star hold on to hydrogen in the face of plasma and radiation from the star? That might depend on the presence of a metal core and thus magnetic protection field.

  20. Chris

    @15 Ken. They aren’t just looking at one star at a time. Nothing would ever get done! They have an enormous camera which monitors a large patch of sky with a lot of stars, then look at the intensity over time.

    Part of me has to laugh when I think about the scientists announcing their 1000+ planet candidates. I keep imagining it like an undergrad presentation. “And here you can see the dip in candidate 101 which indicates it’s about ___ earth masses and ____ from the star. Now here we have candidate 102…” I know the actual presentations aren’t like this but so much data, hard to know where to start.

  21. Dr. Strangelobe

    So, Kepler (well, the interpreting observers) needs three transits to confirm the existence of an exoplanet?

    “I tell you once
    I tell you twice
    What I tell you three times is true.”

    Lewis Carroll rules!

  22. Christine P.

    @5. Steve: It’s KIC 10593626 according to their paper.

  23. Kurt L

    Now we should point the SETI array at it and see if anyone is home.

  24. Parlyne

    @13 Brando and @17 Larian LeQuella, it works like this: We know the planet has radius R = 2.4 R_E, where R_E is Earth’s radius. This means that it’s volume should be V = (2.4)^3 V_E. It its average density is the same as that of Earth, its mass will be M = rho_E V = (2.4)^3 rho_E V_E = (2.4)^3 M_E. The surface gravity will be GM/R^2, so we can plug in what we have for both M and R and get GM/R^2 = G ((2.4)^3 M_E)/(2.4 R_E)^2 = 2.4 GM_E/(R_E)^2, or 2.4 time Earth’s surface gravity.

  25. peterjfrigate

    “Embiggen”! A perfectly cromulent word. Simpson’s did it.

  26. @Ken (#18) Kepler is looking (stareing) at about 150,000 stars all at the same time. Pretty cool, eh? :D

    @Parlyne (#25), thanks. I wasn’t running the equation with rho, but rather just M. I see my mistake.

  27. thinker

    one more aspect which would affect habitability of the planet is its trajectory around its sun, because most celestial objects do not orbit stars and black holes in circle orbits and elliptical orbit would easily be able to make it uninhabitable. but nice find anyway.

  28. Dr. Strangelobe (#22):

    So, Kepler (well, the interpreting observers) needs three transits to confirm the existence of an exoplanet?

    Well, consider the fact that one transit “candidate” could be just about anything, including some totally-unrelated object that happened to pass in a direct line between the star and Earth. Two “candidates” could be two separate planets. It takes three at regular intervals to “confirm” that it’s a single exoplanet, and extrapolate other information about it.

  29. Wayne Robinson

    All this talk of a habitable zone worries me. Without greenhouse gases and with an albedo of 0.30, the Earth should have a temperature of -18C, not exactly the temperate place we know. And with a global temperature of -18C, the polar ice caps would expand increasing the albedo causing progressively increasing global cooling and an eventual iceball Earth.

    With an albedo of 0.70 (due to its atmosphere containing a lot of SO2 and sulphuric acid) and its distance to the Sun, Venus would have a global temperature similar to that of the Earth without greenhouse gases (ie around -18C). Its atmosphere with a lot of CO2 has led to a runaway greenhouse effect.

    So it’s the atmosphere that’s critical in determining whether a planet is habitable or not, not its distance to its star.

    And the Earth is habitable for reasons other than its distance to the Sun and its atmosphere. Very early in its history, it collided with a Mars-sized planet which had formed in the same orbit with relatively low velocity causing the two to merge ejecting lighter crust material to form the Moon, and resulting in the Earth have less crust, more core.

    Having a relatively large satellite in the Moon stabilizes the Earth’s tilt like a gyroscope, allowing relatively stable seasons. Having a thin crust allows tectonic plates and hence volcanos both of which cycle carbon in the form of CO2 and carbonate rocks from the atmosphere to the Earth’s crust and mantle and back again, again tending to stablise the greenhouse effect (over broad ranges!). Having more iron/nickel core means more of a magnetic effect diverting electrically charged radiation from the Earth’s surface.

    So from our series of one (the Earth/Moon) we ‘know’ that having a large satellite is critical for the development of intelligent life.

    Kepler-22 could be freezing cold or stifling hot. There’s no way of telling on the current figures.

  30. Ciaran

    @9 James and others: The mass goes up as R^3 and the gravitational force is proportional to M/(R^2) so it goes up proportional to the radius.

  31. Derek

    @ Wayne – you said, “So from our series of one (the Earth/Moon) we ‘know’ that having a large satellite is critical for the development of intelligent life.”

    No, we only believe it was beneficial in our case. That doesn’t make it necessary.

  32. You know what it means? Keplerians with superpowers if they visit Earth. And since their superstrength comes from their hyper-gravity evolved bodies, and their star is also yellow, we can´t use the old Red Sun trick.

    We´re doomed, DOOOMED!

  33. John Adams

    And if there is intelligent life, the sheer distance will protect the inhabitants from U.S./NATO invasions.

  34. @Wayne Robinson (#30), what you are describing is the rare earth hypothesis. It has many flaws that have been addressed. Not to say that all those conditions weren’t nice for us here on Earth, they are far from a requirement. :)

  35. John Adams

    Wayne Robinson says:
    “So it’s the atmosphere that’s critical in determining whether a planet is habitable or not, not its distance to its star.”

    It’s BOTH, Wayne.

  36. RwFlynn

    Just shared this on my facebook. Hope this lead pans out and we get really REAL confirmation! I’m almost afraid to believe this is true. :P

  37. amphiox

    An object 2.4* the diameter of the Earth, with density similar to Earth, would be able to hold on to hydrogen gas in its atmosphere, and would thus bear more resemblance to an inner system Uranus than the Earth.

    BUT, an object similar in composition to Uranus or Neptune, with 2.4X the diameter earth would by definition have a density less than the earth (as Uranus and Neptune are both less dense than earth).

    The very act of holding on to that thick hydrogen atmosphere would make the object less dense than earth, thanks to the very low density of all that hydrogen gas.

    Such a mini-Neptune would have to start from a much smaller rocky core, and I’m not sure such a smaller rocky core would be hefty enough to accumulate all the gases necessary.

    On the other hand, a rocky protoplanet that reaches 2.4X the diameter of earth with an earth-like density would rapidly accumulate a thick gaseous atmosphere, which would substantially increase the diameter of the resulting planet to something much more than 2.4X that of earth. Indeed, an object with 2.4X the diameter of earth and the same density would have a mass over 13X that of earth, and that is hefty enough to produce a planet almost as big as Jupiter! But that would only happen if there is enough material in that orbital zone during planet formation to grow a planet that big, and at less than 1AU, there probably isn’t. (Assuming that the parent star didn’t have some unusually massive and dense protoplanetary disc)

    Basically, I think our current theories of planet formation would all suggest that whatever the density of this planet, it very likely can’t be the same density as earth, not without some unusual event happening, like for example a massive impact near the end of the planet formation phase blowing off the early thick atmosphere and leaving behind just a dense rocky core.

  38. amphiox

    @13 Brando and @17 Larian LeQuella, it works like this: We know the planet has radius R = 2.4 R_E, where R_E is Earth’s radius. This means that it’s volume should be V = (2.4)^3 V_E. It its average density is the same as that of Earth, its mass will be M = rho_E V = (2.4)^3 rho_E V_E = (2.4)^3 M_E. The surface gravity will be GM/R^2, so we can plug in what we have for both M and R and get GM/R^2 = G ((2.4)^3 M_E)/(2.4 R_E)^2 = 2.4 GM_E/(R_E)^2, or 2.4 time Earth’s surface gravity.

    In other words, greater distance from center of mass exactly cancels out with increasing mass, making surface gravity a direct function of density, at least within a range of reasonable densities (don’t know if this still holds true on the surface of a neutron star….)

  39. Dean

    I think there is something more they did to confirm this. Otherwise, there should be a lot more ‘confirmed’ planets that have had multitudes of sub-7 day periodic transits.

  40. amphiox

    So it’s the atmosphere that’s critical in determining whether a planet is habitable or not, not its distance to its star.

    If a planet is too close to its star, the probability of habitability rapidly drops to zero.

    If a planet is too far away from its star, the probability of habitability drops as well, if somewhat less rapidly, and perhaps never all the way to zero.

    So BOTH distance to its star and atmosphere are critical in determining whether a planet is habitable.

    It is also quite reasonable to hypothesize that the likelihood of habitability is highest for planets inside habitable zones, wherein the widest range of different atmospheric conditions will all still remain habitable, than outside, where very specific atmospheric conditions become increasingly needed to compensate for the suboptimum orbital position.

  41. Thomas Siefert

    Some of the comments reminded me of a short story I read many years ago.
    A lonely space traveller from earth makes first contact with a new species. His initial contact via viewing screen and conversations, reveal them to be very much like humans and the person he is talking to is a very attractive woman who show some romantic interest in him.
    It’s not until they finally meet in the airlock between their ships, he realise that the viewing screen did not convey the scale, as she is three times his size…

  42. StephenH

    @Quatguy: I don’t have any links handy, but I believe that as a planet orbits a star, there’s not only a dip in light levels as the planet transits in front of the star, but there’s also a dip as the planet transits behind the star as well. Effectively, we observe the star blocking the light that’s reflected from the planet. It’d be a much smaller dip, but depending on where it occurred in the orbit of the planet, we could determine whether the orbit is likely to be circular or elliptical. The odds of us seeing an elliptical orbit at exactly the angle necessary to conclude it is circular would be very low.

  43. DigitalAxis

    @18 KenB:

    Given this requirement, it’s amazing that it can find any planets at all.

    Suppose we were to project Earth’s “shadow” (okay, “penumbra” is probably more accurate) onto a sphere 100 light years across. What percentage of this sphere would be within the “we can see Earth transit the Sun” zone?

    Very very small. For every planet Kepler finds, there are probably 100x more around other stars in Kepler’s field of view that aren’t lined up correctly (and then there’s the fact that Kepler is only staring at a tiny portion of the sky, so multiply that number by another ~1000x). I haven’t worked out the math, but the number of planets out there should be STAGGERING.

    The other successful method- radial velocity- still requires pointing at each and every star in turn, so it’s just not feasible to do an RV survey like Kepler yet. Putting massive CCDs out in space and just staring for years at a time, we CAN do.

  44. Anthony

    Basically, I think our current theories of planet formation would all suggest that whatever the density of this planet, it very likely can’t be the same density as earth, not without some unusual event happening, like for example a massive impact near the end of the planet formation phase blowing off the early thick atmosphere and leaving behind just a dense rocky core.

    That’s true, but even at something like half the Earth’s density I think it can still accumulate hydrogen (escape energy scales as density*radius^2), and it could easily be something like a 13,000 km radius rocky object with a 3,000 km deep gas atmosphere.

  45. DigitalAxis

    32. Wayne Robinson

    And the Earth is habitable for reasons other than its distance to the Sun and its atmosphere. Very early in its history, it collided with a Mars-sized planet which had formed in the same orbit with relatively low velocity causing the two to merge ejecting lighter crust material to form the Moon, and resulting in the Earth have less crust, more core.

    Having a relatively large satellite in the Moon stabilizes the Earth’s tilt like a gyroscope, allowing relatively stable seasons. Having a thin crust allows tectonic plates and hence volcanos both of which cycle carbon in the form of CO2 and carbonate rocks from the atmosphere to the Earth’s crust and mantle and back again, again tending to stablise the greenhouse effect (over broad ranges!). Having more iron/nickel core means more of a magnetic effect diverting electrically charged radiation from the Earth’s surface.

    I remember reading somewhere that there are other ways the Earth’s tilt would be stabilized (particularly if we never got knocked off-kilter in the first place by the Mars-sized planet). According to the book I have here, Mercury’s obliquity is 0.1 degrees. I grant you it’s in a resonance with the Sun, but there you go. Venus is 3 degrees if you ignore that it’s upside down.

    But anyway, there are apparently several fallacies with the rare earth hypothesis that stem from assuming a solar system like ours but minus ONE THING could reasonably exist. For instance, if we didn’t have a Jupiter (or Saturn) to catch comets for us, Earth would have been more frequently bombarded. At the same time, though, a system without a Jupiter would probably have had less material in it to begin with, and thus fewer comets to do the bombarding, and the Earth is back to being OK.

    We just don’t know enough about planetary system formation to really answer the question of whether the Earth is rare. In light of that, the paper argued that it’s not reasonable to speculate what would happen in a system like ours but with ONE change- there are probably feedbacks we haven’t considered.

  46. DigitalAxis

    @42. Dean

    The other option is that they DO have a lot more 7 day long orbits confirmed, and they’re just sitting on them for the inevitable massive paper because 7 day orbits aren’t nearly as noteworthy or sexy as this orbit in the habitable zone.

  47. LionDancer

    Could this possibly be a planet moon combination that would give the appearance of one large planet?

  48. Mike Saunders

    @47 Digital Axis

    I assume that orbital planes around stars are completely random (I have no idea if this is actually true!)

    Then I assume that the mid point of the planet is in the sunbeam for an observer far away. As long as the distance from the star to observer is much greater than the distance from the star to the planet, it doesn’t really matter. A few light years is good.

    Then I choose the diameter of the star to be that of our sun, and the distance of the planet to the star to be the same as the earth-sun relationship.

    I found there is a 0.0042 radian slice that the orbit can occupied and be seen by a single observer. If the orbital plane is random, this means there is a 0.3% chance the orbit is aligned properly. Therefore, for every 2000 planets Kepler discovers, there are about 668,000 more that will go unseen! Of course this also assumes that the average planet is earth-sun distance, and the average star is as big as the sun. If the planet is a lot closer, the chance goes way up! This is one reason why closer planets are more common in Kepler’s dataset, the other being their short orbital period.

    To find out how many planets Kepler is missing because it only looks at a very small part of the sky is more difficult, because the distribution of stars in the sky wrt our galaxy is not random at all.

  49. Eugene

    FYI, the star Kepler-22 is 600 lightyears away

  50. @23. Christine P.: Thanks!

    So, looking up KIC 010593626 on the Pale Blue Dot site (palebluedot . whitedwarf . org), we get:
    R.A. = 19h 16m 52.2s
    Dec. = 47° 53′ 4.1″
    lat, lon: 47.8844722222222, -109.2175
    Mag.: 11.66
    Teff: 5606
    log g: 4.355
    [M/H]: -0.38

    So, the star is slightly cooler than the sun, slightly lower surface gravity, and slightly lower heavy element content. Overall, a pretty sun-like star by the sounds of it.

    I also checked to see if it had been adopted yet and it’s marked “reserved”. :-)

  51. Ron

    Thanks Phil, for your outstanding explanation for the laypeople among your readers.

    You’ll be happy to know that the online media is already twisting the facts with their usual lazy and sensationalist methods. Check out the Yahoo landing page. The headline says that Kepler-22b “can sustain life” and has a comfy surface temp of 72°. Who knew?!

    Sure, the article itself clarifies those statements, but who needs tedious details and facts when you can grab headlines!

  52. Thameron

    Why are people so excited about this and these artists renditions of what it looks like? Was this really a shock to anyone once they started finding out that there were really a lot of planets out there? Some things lost in the hubub – 1) Human beings won’t be going there any time soon if ever. 2) If it does have life it is probably pond scum. In fact I suspect that most galactic life is unicellular considering that unicellular organisms dominated most of the history of life on earth. 3) Even if we could somehow go there if it does have life then that means it would be quarantined to avoid terran biological contamination. Any planet in our own solar system that has life likewise means a quarantine. This is no doubt just one of many such planets that will be discovered. Will you be as excited when the fifth one is found?

  53. andy

    OK, let’s pull out our old friend Seager et. al. (2007) “Mass-radius relationships for solid exoplanets”. We then invert the mass-radius relationship to solve for the mass of a 2.38 Earth-radii planet.

    Theorists’ planets:

    Pure iron: 431 Earth masses (using modified polytropic EoS)
    Pure silicate: 21.5 Earth masses
    Pure ice: 7.58 Earth masses

    Multi-component planets:

    Mercury-like (67.5% iron, 32.5% silicate): 62.7 Earth masses
    Earth-like (30% iron, 70% silicate): 32.4 Earth masses
    22.5% iron, 52.5% silicate, 25% ice: 17.5 Earth masses
    Ganymede-like (6.5% iron,48.5% silicate, 45% ice): 12.2 Earth masses
    3% iron, 22% silicate, 75% ice: 9.21 Earth masses

    All these masses are suspiciously high, particularly for the compositions without an ice component. Kepler-22b is almost certainly not a rocky planet: all known planets in that kind of mass domain are volatile-rich Neptune-class planets.

    The icy compositions are somewhat lower masses, but again there is evidence that planets in this mass range retain some gaseous component, i.e. they are mini-Neptunes.

    This is not a habitable planet. It is probably a Neptune-like world, for which the concept of habitability based on a carbon-dioxide/water greenhouse on a terrestrial-type planet does not apply. Move along.

  54. Mike Saunders

    @ andy

    I follow your analysis until you state “All of these masses are suspiciously high”

    Why do you think that? What is your source that these are too high?

  55. andy

    @Mike Saunders: ok to explain what I meant by “suspiciously high”: first we can consider the masses of Uranus and Neptune which are 14.5 and 17.1 Earth masses. All planets so far found in this mass domain with measured radii have densities which confirm a Neptune-like structure, with one exception which appears to contain a larger gas fraction, i.e. it is even further from being a terrestrial. The fact that the lowest-mass terrestrial planet – the rather implausible (from the point of view of formation mechanism) pure-silicate composition – is in the super-Neptune domain suggests that this cannot be a terrestrial planet. A 1.36 Jupiter-mass ball of pure iron is even worse in terms of plausibility.

    Furthermore the statistics of the Kepler planet population and the results from radial velocity surveys suggest that if the studies are sampling the same planet population, the differences in statistics can be resolved by having two types of planets: terrestrial “super-Earths” and volatile-rich “mini-Neptunes”, with the terrestrials dominating toward 1 Earth mass and the mini-Neptunes dominating by the time you reach 10 Earth masses. Again the high inferred masses for terrestrial compositions for Kepler-22b are implausible.

    The icy compositions are also close to the Uranus-mass domain, again suggesting that the planet is likely to have retained a gaseous component in addition to the “solid” constituents. Division between super-Earths and Neptunes has traditionally been assumed to be 10 Earth masses, but volatile-rich Neptune-analogues have been found at still lower masses than this. All in all, the masses that come out of the relationship put the planet in a domain where accretion and retention of a gaseous component should be expected.

  56. Messier Tidy Upper

    Superluminous news even though so much is still uncertain. :-D

    Great write-up and diagrams – wow they sure did those quickly, great work. :-)

    CONGRATULATIONS KEPLER – BEST EXOPLANET YET!

    Still so little known for sure, if only we could go there and find out.

    So very many questions in need of answering and these are just the ones we know to ask :

    1) Is Kepler 22 b a Gas dwarf / mini-Neptune or a Rock Giant or another type of planet again?

    2) What atmosphere if any has it got? Is it’s atmosphere carbon dioxide rich or nitrogen rich or hydrogen and methane rich and is it in layers allowing an ozone layer and ionosphere?

    3) Does it have oceans or lakes and are they right for life versus too acidic or alkaline or hot or cold or ..?

    4) How quickly does Kepler 22 b rotate and how does this effect its climate, is its axis upright or on its side

    5) Does it have plate tectonics, a magnetic field, volcanism, a geology that allows metal and other useful ores to be mined by any putative sentient inhabitants?

  57. amphiox

    Why is it that on these types of threads someone always, always pipes up with some variant of “oh we’ll never be able to go there, why should we be interested?”, as if that had any relevance at all whatsoever.

    Is not just knowing that such things exist and that we are able to find them out enough?

  58. amphiox

    Pertaining to the question as whether this object resembles something like earth vs something like Neptune, it is quite interesting to note that even the artist’s conception shown above looks quite a bit more like Neptune than earth.

  59. Messier Tidy Upper

    Plus more questions if only we could answer :

    (6.) What is the ratio of land to sea and maybe ice? Is this stable or shifting, over seasons or aeons – ice ages and extreme summer / winter variations? If it has continents how are they configured?

    (7.) How stable is its star – and how old? What’s Kepler 22 A’s spectral type, age, distance from us and metallicity? How long and violent is its starspot cycle?

    (8.) Is there Keplerean Twenty-Two B~ese life and has it developed any intelligence – could we detect signals from them or they from us if sufficiently advanced.

    (9.) What else in its the Kepler 22 planetary system – what other wandering stars (ie. planets) share its night sky? How many comets meteors and asteroids does it see and is its orbit clear – if not we’ve only found a “dwarf planet” no matter how big it is assuming we follow the absurd IAU decree! ;-)

    (EDIT : Actually as noted on another thread the IAU ludicrously in my view refuse to count exoplanets as planets at all – a planet by definition orbiting only our Daytime Star just like they refuse to count the ice dwarfs like Pluto and Eris and Sedna but that’s another really long story and side issue.)

    (10.) Can we now find a better name for this marvellous new found world? Will we continue just calling it by the catalogue name of Kepler 22b – or not Kepler 22 b? ;-)

    So many possibilities for what Kepler 22b might be :

    I) A Gas Dwarf or mini-Neptune that’s alien to anything we know fromour solar system and probably lifeless or at least sentience~less – but could it have a large moon witha difference?

    II) A Rock Giant “Super-Mercury or Super Venus with a mass and position that match habitable criteria but not other vital factors. A waterworld that’s allocena or a land world that’s all sand?

    Or

    III) A SuperEarth that finally lives up to the term?

    Wonder if and how we’ll ever know .. ?

  60. Sam H

    :o :D I AM INTENSELY EXCITED BY THIS NEWS. This kind of planet – a roughly Earth-mass planet in the habitable orbit of a sunlike star – is what we were looking for all along. AND LOOK HOW SOON WE DETECTED.
    Of course, anyone realizes that: given the very low percentage of systems aligned to enable transit detection AND the fact we found it after so little searching – indicates that – statistically – OUR GALAXY ALONE IS TEEMING WITH THEM.
    So sure this planet may not be rocky (although who’s to say life of some sort can’t develop on such a world??), but still – if one plugs in reasonable values for the first few variables in the Drake equation, say 60% of all stars forming planets and 10% of them habitable (by our standards), then our galaxy (assuming 400 billion stars) contains 24 BILLION habitable planets. THE BIG QUESTION WILL BE ANSWERED SOON FOLKS. SOON.
    (as well: this planet may not be rocky, but a mass measurement should nevertheless be made as soon as possible with the best equipment available (HARPS and HIRES maybe). And I’m not sure if this is possible, but every available sufficiently large IR telescope in the world (ground or space – Spitzer if at all possible) should be trained on this system at the predicted date of the next transit. An atmospheric and temperate analysis then might be possible. The thing that REALLY gets me excited is that – IF this planet is rocky and habitable – THEN THE BIG QUESTION COULD POSSIBLY BE ANSWERED BY THIS TIME NEXT YEAR. :D

    (unfortunately we’ll all be dead soon after. Well at least we were able to go down knowing the answer!! ;) :D)

  61. Steve Morrison

    @Thomas Siefert:

    That one sounds like “Cosmic Casanova” by Arthur C. Clarke.

  62. Charlie Flores

    it look like… it just the first know as! world in old .. that the world start in only one land… before its starting to separate…. ???? Its already confirm that this planet has air?

  63. Messier Tidy Upper

    @52. Mike Saunders :

    I assume that orbital planes around stars are completely random (I have no idea if this is actually true!) Then I assume that the mid point of the planet is in the sunbeam for an observer far away. As long as the distance from the star to observer is much greater than the distance from the star to the planet, it doesn’t really matter. A few light years is good. Then I choose the diameter of the star to be that of our sun, and the distance of the planet to the star to be the same as the earth-sun relationship. I found there is a 0.0042 radian slice that the orbit can occupied and be seen by a single observer. If the orbital plane is random, this means there is a 0.3% chance the orbit is aligned properly. Therefore, for every 2000 planets Kepler discovers, there are about 668,000 more that will go unseen! Of course this also assumes that the average planet is earth-sun distance, and the average star is as big as the sun.(Emphasis added – ed.)

    Sorry but that lattter assumption is false because the average star is actually a red dwarf star which has far less mass, luminosity and is relatively tiny in size compared to our Sun.

    When it comes to average planet its a bit harder to determine given the selection bias at work in gathering our current sample set and understanding.

    In our own solar system most of the planets – especially counting the ice dwarfs ie Pluto, Eris and Sedna orbit outside Earth’s position – Pluto is really an average (even larger than average actually) planet using a reasonable definition of the word. (NOT the IAU one which exclude ice dwarfs and exoplanets is logically flawed and, well, I could go on about that for days!)

    Of known exoplanets a fair percentage are Hot Jupiters and eccentric orbiters but – especially for the former – that’s probably disproportionate because of the selection bias. Hot Jupiters and Hot Neptunes are quicker and easier to find with our current technology and so we’re finding a lot of close in massive planets although the number of low-mass “gas dwarfs” and SuperEarths is constantly growing. I suspect we’ll find that the trend of lower mass objects being more common continue sfor planets as it does for stars – hence most worlds in the universe will likely be low mass rocky or icy worlds orbiting further from their stars. Neptune type ice giants it seems to me will also prove fairly common and higher mass Jupiter type worlds will be rarer although we’ll really still have to wait and see until our knowledge in this area has grown considerably.

    How many habitable planets are out there still seems like a very open and uncertain question to me. When it comes to life existing on those planets I suspect we’ll find that life is common at a very simple level but intelligent highly technological life is exceedingly rare based simply on the history of life on Earth.

    @60. & #58. andy : Thanks for those informative comments and your analysis there. Good work even if the results are somewhat disappointing in terms of Kepler 22 b being more Gas Dwarf (as Seager herself called them) than Rock Giant. :-)

    @63. & #62. amphiox :

    .. it is quite interesting to note that even the artist’s conception shown above looks quite a bit more like Neptune than Earth.

    Yep. Of course of all the gas giants Neptune is the one that appears most like Earth at a glance being the otherblue planet and all! ;-)

    I’d agree that certainly that Kepler 22b looks more comparable to Neptune there. Wish they’d added Neptune to the same scale there for direct comparison too.

    Why is it that on these types of threads someone always, always pipes up with some variant of “oh we’ll never be able to go there, why should we be interested?”, as if that had any relevance at all whatsoever. Is not just knowing that such things exist and that we are able to find them out enough?

    Seconded by me. We can spot a world that small around a star fainter than our own from 600 light years away. We can learn about itsmass, calculate its likely properties and have some sort of understanding of it. :-o

    Accomplishing that by itself is enough to fill me with awe and wonder. It is just a remarkable thing to be able to do. Yes, I’d love to know more, love to have FTL and fly there quickly for a survey of it but, hey, let’s not forget how difficult and marvellous just finding and learning about Kepler 22b really is to begin with.

  64. Holy Haleakala! You should be ashamed of yourself Phil. “Bad Astronomy” indeed! WHATEVER you meant by “2.4 times *bigger*” (mass? volume? diameter? radius? circumference?) — there’s still not a direct relationship between any of these and surface gravity, which of course takes the planet’s radius into account as well as its mass. A planet 2.4 times Earth’s mass (assuming that’s what you meant) and made of materials of similar density will NOT have 2.4 times the surface gravity.

    Back to school time…
    http://en.wikipedia.org/wiki/Surface_gravity#Mass.2C_radius_and_surface_gravity

    And I see now several others have pointed out the same thing. TV “scientists”… sigh.

  65. Daniel

    to bad 600 light years would take exactly 12,366,600 years to travel to in the fastest man made craft the challenger how about we find a way to reasonably travel such a distance and look for such planets up close instead of gettin everybody worked up over a plain and simple no one knows situation nasa in my book is waistin money lookin instead of findin ways to get to these maybe’s… yeah great its a good find good maybe it could be but instead of spendin years spendin money and guessin lets find a way to get to them and then say you have something cuz right now you really still have nothing if you cant get to it who cares!

  66. Messier Tidy Upper

    In case folks are curious about how the mainstream media is reporting this news, this media article :

    http://www.adelaidenow.com.au/news/world/nasa-confirms-super-earth-that-could-hold-life/story-e6frea8l-1226214730492

    Seems a trifle more than a trifle too sure and optimistic esp. given what we have gathered from this thread* claiming :

    … it [Kepler 22b] has a shopping mall-like surface temperature of near 20C, scientists say. …[Snip] … Floating on that “world completely covered in water” could be like being on an Earth ocean and “it’s not beyond the realm of possibility that life could exist in such an ocean,” Batalha said in a phone interview.

    But is otherwise not too bad for a mainstream media piece and has a great quote or two incl. :

    “This is a phenomenal discovery in the course of human history,” Geoff Marcy of University of California, Berkeley, one of the pioneers of planet-hunting outside Earth’s solar system, said in an email. “This discovery shows that we Homo sapiens are straining our reach into the universe to find planets that remind us of home. We are almost there.”

    Also noting there that :

    “..it would take a space shuttle about 22 million years to get there.”

    Which actually somewhat surprisingly beats this news item :

    http://www.abc.net.au/news/2011-12-06/earth-twin-planet-discovered/3714358

    by the Australian Broadcasting Comission channel & also this similar one :

    http://www.bbc.co.uk/news/science-environment-16040655

    by the BBC who I might have expected better from in the more acurate, more cautious, less hyped stakes. “Earth 2.0″? Twin planet? Definitely 22 degrees Celscisus? I doubt that very much! :-(

    —————————–

    * If commenter Andy here (#58 & 60) has calculated that this is probably a Gas dwraf rather than a rock giant world why can’t / don’t the Kepler people and NASA groups also work that out and note that more strongly in their news releases and initial announcement?

    but does provide some good info

  67. Dragonchild

    The diversity of planets is both a good thing and a bad thing. As Phil said, Venus out near Mars’ orbit would be a very different world. Earth IS rare — of course, it’s unique! Looking for another planet EXACTLY like it is a waste of time. What’s not necessarily rare are the conditions for life. In that context, it’s helpful to remember that our system — despite having eight major planets — is a pathetically small sample size. To apply confirmation bias here among the galaxy’s billions of planets is. . . well, I hope we all see how foolish that is. Even within our system, the lesson from the Voyager missions is that planets and moons are far more diverse than the imagination can possibly. . . well, imagine. The Moon is RIGHT next to Earth and has no atmosphere to speak of. Titan is basically a “gas dwarf”. It’s best to think of exoplanets as having about as much consistency as rolling handful of dice — they’ll average out into patterns over time, but what an individual planet is like is anyone’s guess.

    “can you clarify whether the number 290 was enough to tell you that it had to be in the habitable zone, or if it would be possible that it is really close to the star and going slow, or really far from the star and going fast?”

    Here’s the simplest way to put it: If a planet orbited too slowly close to a star, it’d fall in. If it orbited too quickly far away, it’d fly off and become a rogue planet. Like rolling a marble into a shallow bowl, smaller orbits go faster.

  68. For those asking: I meant 2.4 times the diameter of Earth; I had that in the post originally but must have deleted that line before I posted the article (I distinctly remember writing it).

    As for AdmiralQuality (69): You may wish to avail yourself of my one commenting rule. As for "going back to school", please note that I did in fact specifically make the assumption in my calculation that the planet had the same density as Earth. In that case, surface gravity scales directly and linearly with radius (or diameter if you wish).

  69. @70. Daniel : December 5th, 2011 at 8:30 pm

    too bad 600 light years would take exactly 12,366,600 years to travel to in the fastest man made craft the challenger ..

    22 million years in a space shuttle according to one news article. (Adelaide Now site.)

    However, the Space Shuttle ‘Challenger’was NOT the fastest man made craft.

    For Human spaceflight the fastest ever was Apollo 10 crewed by Tom Stafford, John Young and Eugene Cernan.

    According to the 2002 Guinness World Records, Apollo 10 set the record for the highest speed attained by a manned vehicle at 39,897 km/h (11.08 km/s or 24,791 mph) during the return from the Moon on May 26, 1969.
    – Apollo 10 wikipedia page. (Linked to my name here.)

    (Why it was specifically Apollo 10 on that one flight that set the record I do not know. Anyone care to enlighten us all?)

    Whilst for an unmanned robotic spaceprobe I think New Horizons holds that record -and the overall one too at, well, very much faster speeds again.

    Not exactly sure how long New Horizons would take to get to Kepler 22 b – but it would still be in the millions of years. We do need to work onbuildinengiens thatcan travel at reasonable speeds in that regard! Light takes 600 years meaning incidentally we’re seeing this exoplanet and they’d be seeing us as it was in 1411 around the time of King Henry IV of England and the Ming empire in China.

  70. Good point Phil, gravity does scale linearly with radius/diameter when planets are made of exactly the same materials, in exactly the same distribution. Would we expect that Kepler 22 b would be an exact, scaled up version of Earth, with proportionally sized cores, mantles, crusts of similar densities? Bit of a reach, but I suppose for lack of anything better to assume, why not?

    I just think it’s amazing that, for example, on the “surface” of Saturn you weigh a bit less than on Earth. A counter intuitive point that too often gets ignored.

    Thanks for the clarification.

  71. Tim G

    I have a copy of the 1964 book, Habitable Planets for Man. Based on the physical parameters of the terrestrial planets in the Solar System , it gives a formula to estimate the average density of a terrestrial planet.

    average density in grams per cubic centimeter = 2.770 e^(0.6904R)

    where R is ratio of the radius of the planet to Earth.

    The larger the terrestrial planet, the more compressed it is.

    An R value of 2.4 gives 14.524 grams per cc ( compared with 5.5248 grams per cc that the formula gives for Earth ). Compared to Earth, this means a mass of about 36 times as large, a surface gravity 6.3 times as large, and an escape velocity 3.9 times as large. I suspect that this method of estimating density could produce a value that is way off but I think the density of Kepler-22b is greater than Earth and therefore its surface gravity is more than 2.4 times as great.

  72. @ ^ Tim G. : Good source that book. :-)

    However, thing is that Kepler 22 b may well NOT be a terrestrial rocky planet but instead a micro-Neptune type one composed of fluids and gases rather than solid rock.

    @ 74. “Whilst for an unmanned robotic spaceprobe I think New Horizons holds that record ..”

    Wikipedia confirms this noting :

    New Horizons was launched on January 19, 2006, directly into an Earth-and-solar-escape trajectory with an Earth-relative velocity of about 16.26 km/s (58,536 km/h; 36,373 mph) after its last engine shut down. Thus, the spacecraft left Earth at the greatest ever launch speed for a man-made object.

    Source is linked to my name here. So if anyone ever wants to know where the fastest thing ever built & flown by humans is, well, its on its way to Pluto! :-)

    @70. Daniel : December 5th, 2011 at 8:30 pm

    to bad 600 light years would take exactly 12,366,600 years to travel to in the fastest man made craft the challenger how about we find a way to reasonably travel such a distance and look for such planets up close instead of gettin everybody worked up over a plain and simple no one knows situation nasa in my book is waistin money lookin instead of findin ways to get to these maybe’s… yeah great its a good find good maybe it could be but instead of spendin years spendin money and guessin lets find a way to get to them and then say you have something cuz right now you really still have nothing if you cant get to it who cares!

    Okay, take a breath. Did you mean all that to be one sentence – ever heard of punctuation? :roll:

    how about we find a way to reasonably travel such a distance and look for such planets up close

    Wish we could but easier said than done. FWIW, I’m pretty sure that people *are* looking into making faster space travel possible but FTL is only at the ideas stage right now. Relativity suggests that nothing can go at the speed of light. That may prove to be a physical limit we just can’t beat. SF dreams aside. I hope we can one day but it may never happen.

    instead of gettin everybody worked up over a plain and simple no one knows situation

    Well, there are things that astronomers *do* know here : The planet has been confirmed so we know it exists and we know some verybasic physical properties such as its radius (2.4 x earth diameter) and its orbit. Yes, there’s also an awful lot we don’t yet know but we may be able to learn now we know where to aim our telescopes and instruments.

    Couple of other points. Firstly, its as well as NOT instead of here. We can have both astronomers detecting and studying exoplanets *and* engineers and physicists working on building faster spacecraft at the same time just as you can have a plumber an electrician and a concreter working on building a house all at once too.

    Secondly, getting worked up? This sort of discovery will naturally excite people even if Kepler 22 b is not yet an Earthlike world its a good step in the right direction and an interesting place in its own right. Who is creating the hype though? NASA? Kepler? The media? Even perhaps just ourselves? Plus is it that bad athing to get excited even briefly by this news. Its a positive step in the search, why not be happy for it?

    nasa in my book is waistin money lookin instead of findin ways to get to these maybe’s…

    Waistin money? Far as I can see the NASA staffaren’t getting any more overweight! ;-)

    BTW, note that NASA is an acronymn (National Aeronautics and Space Administration) so needs to be capitalised. Not that I’m flawless when it comes to typos and grammar myself mind you!

    Oh & again, see my point earlier on doing more than one thing at once. Finding exoplanets is worthwhile and can be done as well as exploring planets, building rockets and coming up with better spacecraft engines.

    yeah great its a good find good maybe it could be but instead of spendin years spendin money and guessin lets find a way to get to them and then say you have something cuz right now you really still have nothing if you cant get to it who cares!

    Me for one! ;-)

    Lots of others too going on the number and contents of the comments here. You may not care, sure, but that doesn’t mean others aren’t interested and if you don’t care then the best thing to do is leave the comments to those who do.

    As for having nothing if we can’t get to Kepler 22b, well, new knowledge and improved understanding is NOT nothing but something. WE have something very important -information and we can alsocombine this with another important thing – our imaginations, our ability to perform calculations and our sense of wonder.

  73. Zero

    Great a planet like in planet Earth that have same Atmosphere will be a great help and its twice the size than earth and its system where Kepler 22b belongs is near on solar system that have a same sun… It’s an improvement to us to find a habitable planet that people can live…

    but how is the gravity of kepler22b? It’s will be suitable for our people to live that planet?

  74. puppygod

    @27 Thameron

    1) Human beings won’t be going there any time soon if ever.

    So? There are many places where we wouldn’t be going any time soon – erupting volcanos, Mariana Trench, Saturn. Doesn’t make them any less interesting.

    2) If it does have life it is probably pond scum. In fact I suspect that most galactic life is unicellular considering that unicellular organisms dominated most of the history of life on earth.

    Actually, that doesn’t seem to be the case – we have multicellular life on Earth for more than billion years (and maybe even more than several billions) – that is some serious percentage of the time life is here. Also, multicellularity evolved many times, so it’s not that unusual or rare. Rather, complex life seems to follow naturally.

    3) Even if we could somehow go there if it does have life then that means it would be quarantined to avoid terran biological contamination. Any planet in our own solar system that has life likewise means a quarantine.

    Yes. Though probably local lifeforms will be better adapted to local conditions than any invaders anyway. Still, better not to take chances.

    This is no doubt just one of many such planets that will be discovered. Will you be as excited when the fifth one is found?

    Personally? Yes, I would. The quantity and variance among exoplanets are among things that makes such discoveries so exciting.

  75. reidh

    You think that is “habitable” you should be the first to be sent to live there, if you call that “living”.

  76. reidh

    You think that is “habitable” you should be the first to be sent to live there, if you call that “living”.

  77. reidh

    You think that is “habitable” you should be the first to be sent to live there, if you call that “living”.

  78. reidh

    You think that is “habitable” you should be the first to be sent to live there, if you call that “living”.

  79. andy

    I personally do not like the term “gas dwarf” very much: the composition of these planets is dominated by heavy elements, i.e. the “ice” or “rock”, rather than “gas” (hydrogen/helium).

    Currently as far as I can tell the best candidate for a habitable exoplanet is the recently-announced planet Gliese 667 Cc, which is an RV-detected planet of at least 4 Earth masses that receives 90% of the Earth’s insolation. This one hasn’t yet hit the press release circuit yet, expect “habitable planet found in triple star system” news stories to arrive in the near future…

  80. mike

    You say this is “[Kepler’]s first planet in the habitable zone of a star like the Sun.” I know HD85512b was discovered by HARPS, but isn’t it also in the inhabitable zone of a star like the sun?

    It’s interesting that the Kepler discovery provides the volume without the mass while the HARPS discovery provides the mass not the volume. Can Kepler be used to determine the volume of HD85512b? Would you care to guess which one might be more Earthlike?

  81. Jess Tauber

    Just remember you can help find these planets with Kepler data- go to http://www.planethunters.org/, and NO, you don’t get to keep the ones you find. Sheesh…

  82. Jess Tauber

    Re 65: ’24 billion habitable planets.’

    All Borg. Or Republican. Which amounts to the same thing….

  83. #44 Thomas, #66 Steve:
    Yes, that is definitely “Cosmic Casanova”, by the late Sir Arthur C. Clarke.
    The people on the planet are not “a new human-like species”; they are humans, who colonised the planet several thousand years earlier, and contact was later lost. The planet has low gravity, so a few thousand years of evolution has led to the ending which Thomas describes.

  84. Nigel Depledge

    Brando (13) said:

    I was about to ask the same question as James.

    I’m not very physics inclined, but it’s not as simple as “2.4x more massive –> 2.4x as heavy on the surface,” right? If it were the same size as Earth and 2.4x as massive, then sure, but being further away from the center should have some effect — possibly a substantial one.

    For example, according to WolframAlpha, the moon is 27.2% the size of Earth yet its gravity is only 16.6% due to it being only 60% as dense comparatively.

    You are kind-of correct.

    But this newly-discovered exoplanet is not (necessarily) 2.4 times the mass of Earth. It is 2.4 times the diameter. Therefore, assuming the same average density (which it probably is not), it will have (2.4)^3 (= 13.8) times the Earth’s mass. Its surface will be 2.4 times as far from the centre of mass as is Earth’s surface, and this needs to be taken into account.

    If I understand correctly, gravitational force decreases with the square of radius (for a constant mass).

    Thus, for 2.4^3 times the mass and 2.4^2 times less surface gravity, these cancel to the extent that surface gravity scales directly with radius. Assuming, of course, constant density.

  85. Nigel Depledge

    Wayne Robinson (32) said:

    So it’s the atmosphere that’s critical in determining whether a planet is habitable or not, not its distance to its star.

    Well, the atmosphere has an obvious influence, but the distance to the star is a significant factor.

    Were Earth transplanted to the orbit of Mercury, it would lose its atmosphere pretty rapidly and become uninhabitable. Were Venus transplanted to the orbit of Titan (say), it would rapidly become too cold for liquid water to exist. The habitable zone is that region around a star where liquid water may exist, if other conditions are right.

  86. Gunnar

    Interesting news indeed, but it is 600 light years away. I can’t help feeling somewhat frustrated by the fact that we still don’t know whether or not either of the stars in the Alpha Centauri system has planets, despite their being closer to us than any other known stars. I understand that this is largely due to the fact that it is inherently much harder to detect planets in a multiple star system–even one quite close to us–but that doesn’t make it seem any less frustrating. As much as I enjoy finding out about these other exoplanet discovery news, what will really grab my interest and excitement is if and when we find stable planets in the habitable zone of either or both Alpha Centauri A and B.

  87. @ ^ Gunnar : Well, yes & no. As I understand it, Alpha Centauri’s problem is that if it does have planets – and modelling suggests it should* – then these are likely small low mass rocky worlds which are hard to detect especially for sunlike stars.

    People have been looking and, I think, set a minim mass on any planets that do exist around either of the main Alpha Cen stars. IOW it has no Jupiter or Saturn mass worlds probably not even any Neptune’s or “SuperMercurys” either. (“SuperEarth” seems too much of an abused misnomer for me to want to use.)

    Proxima Centauri has already provided at least one false alarm. From ‘The New Challenge of the Stars’ (Moore and Hardy, 1977.) :

    “There have been suspicions that Proxima, too, may have a planet … The evidence at present is slender, but the planet may exist … relatively near its weak, red sun, around which (it is calculated) it orbits in 10-12 days …” (Page 45, brackets original.)

    Sadly, Proxima’s putative planet was ruled out or at least minimised. See page 30, July 98 Astronomy – careful HST monitoring ruling out those prior suggestions and indications.

    Still, I hope and would even go as far as saying I expect that we’ll discover planets around one or both of the main Alpha Centauri stars at some stage.

    ———

    * Note that apparently :

    A new paper just published [in March 2008 -ed.] by a team of planet-hunters shows that theoretically speaking, not only can Alpha Centauri have planets, it should have them.

    Source : Theoretically, Alpha Centauri should have planets posted on this blog by Dr Phil Plait on March 7th, 2008 & is linked to my name here.

  88. Has anyone yet calculated what the conditions how any large Titan or Europa type moon around Kepler 22 b could be like?

    Say, Kepler 22b – or the “Christmas planet” as one of the astronomers called it* – is a gas dwarf that has migrated inwards. If it did have a large moon like Triton or Titan or Ganymede could that moon sustain liquid water and perhaps life?

    Would it be protected by the “Xmas Planets” magnetosphere assuming it has one – or instead exposed to more radiation because of its environment, would it get a similar sort of tidal heating as Europa or Io get from Jupiter?

    Would it face a significantly greater number of bolide (comet and asteroid) impacts sufficent to make life extinct too frequently to develop past the microbial stage if at all?

    Come to think of it, if Kepler 22 b had rings of ice and dust could they still exist or would they evapourate away? Could the “Christmas planet” have rings of droplets of water that freeze around one side when they fall into the planet’s and moon’s shadowsn and melt into raindrop sized spheres of liquid when in the sun Kepler~light again?

    Also, please, can somebody, anybody, tell me the primary stars spectral type?

    PS. Someone on the last exoplanet thread (andy?) mentioned another more promising planetary candidate – was this the one or was it another one? Vaguely recall one of the Gliese stars mentioned perhaps?

    ——————–

    * Quote from the article linked to my name via Adelaide now website :

    “It’s a great gift,” Borucki (Chief Kepler scientist William Borucki – ed. )
    said. “We consider this sort of our Christmas planet.”

    Guess its better than a catalogue entry and follows the tradition of Christamas and Easter Islands on Earth. :-)

  89. Messier Tidy Upper

    @85. Jess Tauber : “Re 65: ’24 billion habitable planets.’ All Borg. Or Republican. Which amounts to the same thing….

    But .. aren’t the Borg a Collective and wouldn’t that be too “Socialist” sounding for the likes of the Republicans?? Also aren’t the Borg pretty pro-science and intellectually advanced especially on nanotechnology and don’t they have an advanced understanding of biology? ;-)

  90. burjui

    “I have been informed that this is NOT the first planet seen in the habitable zone of another star, but the first seen by Kepler, and moreover the first that is not a gas giant”

    Aren’t HD 85512 b and Gliese 581 d in the habitable zones? There’re super-Earths with known masses, Kepler 22b could as well be just a smaller version of Neptune.
    I don’t get the hype. As far as I’m concerned, the only noteworthy thing here is that the star is Sun-like. This is just, by pure chance, the first such planet confirmed by Kepler, not very Earth-like for that matter.
    According to this site – http://phl.upr.edu/projects/habitable-exoplanets-catalog/list_hab – there are much more interesting candidates in the dataset.

  91. Tom Callahan

    Road trip, who’s with me? We just some canned goods, a change of clothers, a FTL space ship, my ipod… oh, wait… dammit.

  92. rp

    That we can discovering exoplanets at all is truly amazing. Kudos to all the hard work

    A couple interesting questions on the process come to mind on this. I saw discussion that touched on this, but not completely.

    how long is a transit event? minutes? hours? days?

    Is Kepler watching the same section of sky all the time, or surveying different sections all the time?

    If Kepler is not watching the same section of sky all the time, how likely it is it that it might miss a transit event?

    (obviously depends on how long a transit event lasts — somehow it seems to me it would be very short, given the apparent angular diameter of the objects involved and the distance, but that’s just a guess)

    I think that there’s not enough information from the first observed transit that might indicate when to look for a possible second or third, which means discovering these would require combing through months of data records. I assume these days this is computer assisted?

    rp

  93. intothemoonbeam

    I apologize if I missed this in any of the comments, but do we know about how old the the star Kepler 22 is? Is it about the same age of our Sun? It would be interesting to know if it’s old enough for advanced lifeforms to evolve on Kepler-22b or any other planets/moons that might be orbiting it.

  94. Anthony

    how long is a transit event? minutes? hours? days?
    The sun is 1.4 million km across, the Earth’s orbital velocity is 29 km/sec, so an equatorial transit would take 13 hours, one that wasn’t perfectly aligned would take a bit less, and obviously this would vary quite a bit based on location of the planet and the size of the star. Still, ‘hours’ should be true for the vast majority of cases.

  95. frankenstein monster

    2.4 x earth diameter + closer to the inner edge of the habitable zone ? just another oversized venus or hot neptune methinks.
    Even if it is not without solid surface altogether. more mass = denser atmosphere = over the runaway greenhouse effect threshold = super hot temperatures.

    if you find something slightly bigger than earth, and in the colder half of the habitable zone, wake me up. until then…

  96. Regner Trampedach

    Anthony @ 16+48: The question about volatiles, e.g., hydrogen, is whether it would be there to coalesce into a planet in the first place. Most of it would have been blown away by the intense radiation from the contracting proto-star (T-Tauri star). It would be blown out and accumulate beyond the snow-line for gas-, and further out, ice-giants to form – that is at least how it has worked in our Solar System.
    Cheers, Regner

  97. andy

    @102: Regner Trampedach – that problem is mitigated by planet migration. A volatile-rich planet may form out beyond the ice-line and migrate into the inner system. For example, the Kepler-11 system consists of low-density, low-mass planets that have ended up closer to their star than the inner edge of the system’s habitable zone. There is no reason not to expect to find mini-Neptunes in the habitable zones of other stars.

  98. Anthony

    The question about volatiles, e.g., hydrogen, is whether it would be there to coalesce into a planet in the first place.
    Even if you started with no more volatiles than the Earth, our atmosphere is significantly affected by the fact that if UV knocks hydrogen off of water vapor, ammonia vapor, or methane, that hydrogen is likely to escape, and on a larger planet it wouldn’t.

  99. andy

    Incidentally I don’t buy HD 85512b as a habitable planet either, the insolation is very close to that of Venus: in fact according to several published definitions of the habitable zone it is too close to the star. You could perhaps get around that if the planet maintains a high cloud cover, but Venus itself has a 100% cloud cover that puts its effective temperature below that of the Earth and we know what conditions are like on the surface of that planet.

  100. Apart from general scientific curiosity, what is so cool about finding a habitable planet? It is not a surprise that they exist. Even if confirmed, detecting life will be difficult (though perhaps one could detect some signs of life). Still, the presence of life would be no big surprise.

  101. OtherRob

    After reading all these comments, I’m no longer even sure that the Earth is in the habitable zone. ;)

  102. Jared

    > Suppose we were to project Earth’s “shadow” (okay, “penumbra” is probably more accurate) onto a sphere 100 light years across. What percentage of this sphere would be within the “we can see Earth transit the Sun” zone?

    KenB, according to my math, Earth’s penumbra outlines a ribbon about 0.53º of arc wide on that circle.

  103. Commander Nemo

    Ken B @ 31;

    Thanks for the explanation, but, um, I understood the ‘three confirmations’ from the article. I wrote the first line as a question because it worked better in the context of the post.

    Only three? I’d think that four or more would be better before announcing the discovery; but I’m a civilian, and not versed in these matters.

  104. Gunnar

    @MTU,

    Thanks for your reply to my post. :) That was just the kind of additional information I was hoping to get in response, and from just the person I guessed would be most likely to provide it. I had already seen some of what you told me from other sites I had visited, but what you added was a helpful and welcome addition to what I had already found. I had not yet seen Phil Plait’s previous post on this subject, and I thank you for linking us to it! I am not surprised, of course, that Phil had already discussed Alpha Centauri’s planetary possibilities. In fact, I would have been very surprised if I found that he hadn’t.

    I also appreciate the informative comments of quite a few of the other commenters on this thread. I hope I can be forgiven for not specifically naming all of those to whom I feel indebted. :)

  105. Nick L

    Someone needs to break out the Terrestrial Planet Finder plans and start modifying them to handle the distances involved with Kepler-22b because we finally have a good reason to build it.

  106. eyelessgame

    Of course, this is all tempered by the fact that we know there’s liquid water on Europa, Ganymede, Enceladus, and Triton (and, I believe, deep within Uranus, right?), none of which are within our sun’s “habitable zone” — nor are any of them detectable as terrestrial-sized planets, as they’d be lost in the glare of their parents…

  107. @^ eyelessgame : Indeed. Life on gas giant moons is a probable different environment with different criteria for habitability again. I vaguely recall reading an article in one astronomy magazine on the possibility of detecting such exomoons but have forgotten the details. Difficult task to find! :-o

    (and, I believe, deep within Uranus, right?),

    Right. Both Ouranos and Neptune are sometiems described as “ice giants’ having a high water content as opposed to the more hydrogen and helium composed gas giants and so we also think there could be liquid water – albeit at super high pressures and temperatures and possibly in the form of exotic “ices” – inside Neptune while even Pluto and similar ice dwarf planets may have a subterreanean sea inside. (Click on my name here for space-dot-com article on that.)

    @ 85. Jess Tauber (again) : “Re 65: ’24 billion habitable planets.’ All Borg. Or Republican. Which amounts to the same thing….”

    On reflection, if there’s a Star Trek species match for the Republicans it’d have to be the Ferengi who put business and making a profit above everything else wouldn’t it? ;-)

    (Can’t think of any ‘Star Trek’ species match for the Democratic party.)

    @112. Gunnar : Cheers, no worries. :-)

  108. Anthony Ransford

    Perhaps it only has 2 hour days….Then at least on the equator gravity would be earth-ish

  109. I wonder, could a super-earth have moons that would themselves be capable of supporting life? Like hypothetical gas-giant moons in habitable zones… I know gas giant moons are typically tiny compared to their planets, but the Earth’s moon is pretty darn big compared to the Earth.
    For that matter, I wonder if moons might affect the size of planets estimated by the transit method? Could a planet with multiple moons appear slightly larger using the transit method?

    Anyway, this is just generally awesome! :D

  110. @116 MTU: On reflection, if there’s a Star Trek species match for the Republicans it’d have to be the Ferengi who put business and making a profit above everything else wouldn’t it?

    I would’ve said the Cardassians or Romulans, as they’re apparently on board with torture. But yeah, Ferengi fit too :-P

  111. Phillip Helbig: Even if confirmed, detecting life will be difficult (though perhaps one could detect some signs of life). Still, the presence of life would be no big surprise.

    What exactly DOES it take to impress you, then? Sheesh!

  112. pbrower2a

    Temperature and the escape velocity of a planetary body likely dictate what sort of atmosphere is possible and whether life is possible. Jupiter, Saturn, Uranus, and Neptune are chilly and heavy enough that gravitation can hold gases as light as hydrogen (atomic weight 2). Mercury, the Moon, and Pluto are too cold to hold any common gas (not that there is any common gas other than hydrogen or helium at the temperatures of Pluto). Mars and Venus may be quite dissimilar, but their atmospheres consist largely of nitrogen and carbon dioxide characteristic of planets either too hot or too small at their locations, but both planets are marginal for allowing gases (methane, ammonia, and water vapor) between atomic masses 16 and 18. Heavier nitrogen and carbon dioxide remain, but those planets have little water necessary for life. Because biochemistry depends, at least in its start, upon methane (almost all biochemicals are methane derivatives, ammonia, and water, a planet like Mars or Venus is unlikely to harbor life in quantity.

    The Earth can hold gases heavier than those with an atomic weight above 6 — not hydrogen or helium, but clearly methane, ammonia, and water vapor. To be sure, Earth has little methane or ammonia in its atmosphere (oxygen would destroy either quickly), but life on earth suggests the early presence of both as well as water vapor when there was no free oxygen.

    But — we have no good model for a planet that can hold helium but not hydrogen. Would such a planet be amenable to the biochemistry of life?

  113. This article :

    http://www.space.com/12978-alien-planets-rocky-gas-giants.html

    Raises some interesting thoughts on the possible nature of Kepler 22 b and seems somewhat prescient here :

    “The remaining core is pretty much a rocky planet, with a mass anywhere from almost zero to ten or so Earth masses,” Nayakshin said. .. (snip) .. This means the resulting planet could wind up close to their parent star — or farther away, in the area known to astronomers as the habitable zone.

    Wonder if there’s any way to tell and whether this proposed mechanism explains many of the SuperVenus type exoplanets?

  114. MNP

    Now we just need to be able to get there.

  115. OneofNone

    @108: What’s so cool?

    Before detection we knew those items must be out there.
    Now we know those items are out there.

    See the difference? Now imagine talking to some critic.
    This is not just limited to planet discovery.

  116. Jeff

    I’m excited by this , so IF the star is about sun size, I would calculate the ratio of K-22b’s effective temperature to the earth’s by the formula:

    (T(K22b) / T(earth) = cube root (365 days/290 days) = 1.08

    So the effective temp. of this planet would only be 8% higher than earth. Of course, this has nothing to do with surface temperature which is largely dependent on the density and composition of the planetary atmosphere, compare and constrast the sister planets earth-Venus.

    I knew Kepler would yield results, and I knew how I would feel, like I feel today, frustrated that we now do know details about the planet, is it like a terrestrial planet or Jovian planet in composition, is it gaseous or rocky?, what is in its atmosphere and how dense?

    Well, when I was a grad student, even what Kepler HAS DONE would be complete sci fi and my astronomy profs. would have laughed at anyone who thought even this could be done.

    I guess it’s too much to ask for all the details of the planets, maybe I’ll live to see that future mission after Kepler.

  117. GrogInOhio

    @25 Kurt L… my exact thoughts. I’m hoping SETI does something more efficient with regards to this one. I know they’re strapped for funding, but a sharp focus on this candidate seems warranted, if possible.

  118. The thing that’s really frustrating to me about the transit method is that we can detect planets 600 light years away, yet we’re still unsure if the closest star to the sun has a planetary system.

    @94 MTU: But .. aren’t the Borg a Collective and wouldn’t that be too “Socialist” sounding for the likes of the Republicans?? Also aren’t the Borg pretty pro-science and intellectually advanced especially on nanotechnology and don’t they have an advanced understanding of biology?

    I always thought that the Borg represented the logical progression of transhumanism when taken to the extreme. I find the idea of the Borg particularly prescient since they predated the beginning of the “mainstream” use of the Web (when the Mosaic browser first came out) by about 4 years. And don’t even get me started on social networking! IMHO, if there’s a single symbol of the Borg in this day and age, it’s Facebook :-P “You will be assimilated” indeed.

  119. Infinite123Lifer

    For Joseph G…you can’t be that frustrated with the transit method can you? I mean, it is a system of approach as opposed to no system. I am not sure if other techniques exist for finding planets? To look for relatively small bodies in such an ocean of vastness and maybe more importantly darkness without using light discrepanies seems . . . rather non-existent for the time being. I agree with you though it would be an outstanding day if there came a time when we could detect, say, gravitational effects on space-time around a body of mass or search for magnetic fields or possibly see in the dark. I guess the problems with a sonar/radar type system is the distance energy must travel? It would be like throwing a pitch & waiting 10 generations for it to be caught…

    I don’t like the borg, or ferengi, or facebook :)

    I think the HZ concept is truly cool, however Iam excited to learn if Life can sustain itself solelupy on volcanism. There could be planets with no suns harboring Life getting heat and nutrients from the core of their planet. Though we most probably won’t see them or find them if they are outside our solar system because they will be dark’ iam just using a little imagination. I think some of the planets or moons in our solar system might be speculated to have liquid water due to other factors than just solar heating (MTU @ 116).

    As for those who ho-hum it…there is something to be gained/learned from everything. Each discovery potentially leads to new knowledge, new techniques, new ideas and most importantly a freshly invigorating imagination; without which nothing human is possible.

  120. andy

    Transit detection only works if the system is aligned very precisely with our line of sight. There’s no particular reason to believe that any planetary system around the Alpha Centauri stars is going to be in this alignment. In fact if the planets are aligned with the binary star orbit, they will certainly not be in the right orientation for transits.

    Radial velocity studies have been pushing down to smaller planets around Alpha Centauri (gas giants have been ruled out already), but remember that not all planetary systems are going to be detectable. If, say, the system consists of a bunch of lunar-mass planets, it will essentially be invisible to any detection method that is likely to be available for a long time to come. We detect the planets we are able to detect.

  121. @129 and 130: Oh, I know that. I’m not disrespecting the science or the ingenuity, which is indeed incredible. It’s just that as amazing as these technologies are, there’s so much that’s tantalizingly juuust out of reach (such as terrestrial planets around AlphaCen using radial velocity detection).
    I’m complaining to no one in particular, ‘nother words. Remarking wistfully. Whatever :-P

  122. Peter

    (Can’t think of any ‘Star Trek’ species match for the Democratic party.)

    The Dominion

  123. @132 Peter: The best match for the Democratic Party in Star Trek would probably be Humans. The Earth envisioned by Gene Roddenberry is a hard-left Liberal Democrat’s dream come true. Universal everything (healthcare, housing, everything), extensive global government management of resources; you might even go so far as to call it post-capitalist democratic socialism (there are references in a few episodes to society on Earth having somehow “outgrown” money).
    The sort of stuff that makes Rush Limbaugh bolt upright in bed in a cold sweat in the middle of the night, in other words :-P

    The Dominion is quite militaristic, much moreso than Starfleet, so I’m not sure if that’d be consistent with the anti-war crowd within the Democratic party.

  124. @ ^ Joseph G : Yeah, I guess that makes sense.

    So Democratic party = Federation & Republican party = Ferengi – which on reflection makes even more sense given the sexist Ferengi attitude to women too.

  125. @134: Heh, yeah. Well, actually, just Humans. The Federation includes a bunch of other species that may or may not resemble Democrats.
    Though, on the other hand, (regarding Ferengi as Republicans) the Ferengi aren’t terribly religious, particularly compared to some other Star Trek races (Klingons and Bajorans come to mind).

    Now, if you wanted to compare nations to alien races (and you were being particularly uncharitable), you might be able to compare the Dominion to the United States, as it’s composed of a number of different alien races (which can be seen as analogies either to the US’s ethnic diversity or its policy of supporting proxy nations during the Cold War) and very much follows a doctrine of pre-emption (the Changelings in charge basically kicked off the whole thing as a way to keep themselves from being destroyed by the “solids”).
    Actually, I suppose you could also compare it to the former Soviet Union.

    How sad is it that I know more about a defunct TV show then astronomy? :-P

  126. Messier Tidy Upper

    @ ^ Joseph G. :

    (Klingons and Bajorans come to mind). Now, if you wanted to compare nations to alien races ..

    The Bajorans always struck me as a metaphor for the Jewish people – even perhaps Israelis specifically – with their diaspora (remember Ensign Rho Laren?) and persecution and finally returning home. Mind you there are quite a few differences too starting with plural gods incl. Cisko! I could be wrong but I think I read somewhere that Bajor even means something in Hebrew? Can anyone confirm /deny / enlighten us all on that? (Not a Hebrew speaker myself alas.)

    Which, I guess, makes the Cardassians the Arabs! ;)

    The Klingons began* – in TOS – as a pretty straight metaphor – at least in the original series to the evil Soviet empire with, just perhaps if you stretch the analogy far enough, the Romulans as the (Then-red) Chinese. But the Klingons story changed & evolved a lot subseqeuntly to the point where the Klingon species and culture became really so much more than they were originally.

    Not sure you can really draw all that many parallels to politics with various episodes playing up and down various aspects of all the various species /cultures involved. Fair bit of guesswork and imagination in drawing political parallels although I’m sure at least some were intended.

    Dominion = USA I’m not really seeing to be honest as the Dominion was far from democratic and free – can’t really see parallels there for present world politics. Eygpt under the Pharoahs maybe? Romulans – Romans parallel from ancient history too which I guess would make the Vulcans ancient Greeks! Hhmm…

    How sad is it that I know more about a defunct TV show then astronomy?

    Well ‘Star Trek’ is really more a franchise of series not just “a show” isn’t it – if that helps any! Plus (often) a great one at that! ;-)

    There are many SF shows I love and can talk for hours on & I love astronomy and can talk for even longer on that too – just different passions and both interesting, enjoyable and quite often complementary. :-)

    —————————————————
    * True story or so I’ve heard – apparently the Klingon homeworld was originally going to be called “Kling” before they realsied that sounded pretty silly! ;-)

  127. @136 MTU: Yeah, good points. On one hand it’s easy to read too much into the show, on the other hand they did some episodes that were pretty transparent allegories of human interactions. The “Yangs” and “Koms” (Yanks and Commies?) in that one TOS episode come to mind, or the TNG one where Riker got intimate with a member of a race that were all supposed to be androgynous, and gendered members were considered “perverts”.

    Well ‘Star Trek’ is really more a franchise of series not just “a show” isn’t it – if that helps any! Plus (often) a great one at that!
    True, that! :D There was an interesting miniseries on the History channel a few years back, hosted by William Shatner at his most self-deprecatingly ‘arrogant,’ about all the ways that Star Trek shaped the modern world. They actually found some really cool stuff. For instance, some of the people who worked on the very first cell phones pretty much came out and said that they were just trying to duplicate the Star Trek Communicator* :-P And yeah, socially, TOS was pretty darn revolutionary for its time.

    I could be wrong but I think I read somewhere that Bajor even means something in Hebrew? Can anyone confirm /deny / enlighten us all on that?
    I can read Hebrew, but only phonetically, so that doesn’t help much! Seriously, it’s weird – I had a Bar Mitzvah and everything, but I can’t understand the darn words. They pretty much teach you to read the syllables first (at least in the laid-back Reform sunday school I went to), and I guess you’re supposed to learn the rest of the language later :-P Doesn’t sound like Hebrew to me (that soft J:zh sound doesn’t really ring as such), but I’ve been wrong before. I do know that the Vulcan “Live long and prosper” hand gesture is based on the Hebrew letter Shin…

    As far as the Klingons, yeah, I could never fully get over that transformation between TOS and TNG. The TOS Klingons were definitely a heck of a lot more human. I guess rubber forehead technology hadn’t been perfected yet ;)

    Dominion = USA I’m not really seeing to be honest as the Dominion was far from democratic and free –
    Yeah, I was kinda reaching. It doesn’t help that I live in ultraliberaltown, USA, where you’re as likely to hear the guy at the coffee counter talking about the American Hegemonic Empire as about the weather ;) I mean, I’m an unapologetic Librul, and people around here make me look like Newt Gingrich.

    *And the cool thing is, they did, and eventually surpassed them! Shoot, how many Star Trek communicators had global positioning, still and video cameras, magnetic and G sensors, etc etc?

  128. Jenny

    For what it’s worth, here’s my article for Urban Times on the subject.

    http://www.theurbn.com/2011/12/twin-earth-hardly/

    Kepler is providing us with amazing data. I have no doubt that soon enough we will find ‘Earth’s twin’ & it may be that kepler-22b is the one, but it is too early to say that yet. When we do eventually find a habitable planet it will be HUGE news. Let’s not spoil that moment by crying wolf too often

  129. Messier Tidy Upper

    @ ^ Joseph G. : Cheers! :-)

    I do know that the Vulcan “Live long and prosper” hand gesture is based on the Hebrew letter Shin…

    Neat. I didn’t know that one. Thanks. :-)

    BTW. The last few Letterman shows have featured Kepler 22b although David Lettermen &/or his staff seem to be under a misapprehension regarding the term “SuperEarth” thinking that’s Kepler 22b’s name and it has something to do with superman or something! ;-)

    Oh, and that’s its definitely Earth’s larger twin which, yeah, probably not. Still Kepler 22b has got its ‘Letterman Top 10′ moment of fame (even here in Oz) so – yay! :-)

  130. @139 MTU: BTW. The last few Letterman shows have featured Kepler 22b although David Lettermen &/or his staff seem to be under a misapprehension regarding the term “SuperEarth” thinking that’s Kepler 22b’s name and it has something to do with superman or something!
    Bahaha, I didn’t know that. At least they aren’t calling it Krypton or something ;) And at least it’s making the headlines.

  131. Torbjorn Larsson, OM

    Since this may still be active:

    – A clarification to the discussion of other habitables can be found in viewing the press conference. This is the first habitable well within the habitable zone. (As marginal as Earth, in fact.)

    And yes, the paper have them extract the orbit parameters from the observations, so we are good.

    – Re # 58, the Kepler paper (arxiv 1112.1640) has this as a potential terrestrial:

    “Because only an upper limit to the mass of Kepler-22b is available (36 MÅ,1σ), any density less than 14.7 g/cc is consistent with the observations; i.e., the composition is unconstrained. Several planets with sizes similar or less than that of Kepler-22b have been discovered that have densities too low for a rocky composition (Lissauer et al. 2011). However, others, such as Kepler-18b have a size (Rp = 1.98 RÅ) similar to Kepler 22b and a density (4.9 ± 2.4g/cc) sufficiently high to imply that such planets could have a solid or liquid surface. Further, model studies of planetary structure often consider rocky planets with masses of 100 MÅ or more (Ida and Lin, 2004, Fortney et al., 2007). Because there is a possibility that Kepler-22b is a planet with a surface and an atmosphere, a surface temperature will be estimated.”

    So we (at least I) will take heed of that before we “move along”.

    Interestingly the upper limit places Kepler 22-b as “Earth like” in composition according to Seager et al figures. Se we are not looking at a dense terrestrial.

    I don’t know much about planetary models, but apparently Seager et al isn’t the only game in town and a bit dated to boot. If the switch between terrestrials and neptunes has an overlap with as of yet undecided limits, we should keep an open mind on potential surface habitability. That is what the concept is for in the first place; modifiers apply later.

  132. andy

    @143: I still stand by my point that Kepler-22b is not a good prospect for habitability at all.

    The upper limits on the planetary mass at 1, 2 and 3 sigma are 36, 82 and 124 Earth masses. So essentially while the pure-iron composition is ruled out, dense terrestrials would still be formally compatible with the data, if utterly implausible from considerations of planet formation. Some of the presentations at the Kepler Science Conference deal with the issue of the Neptune/terrestrial transition, it is thought to occur somewhere below 2.5 Earth radii, and maybe nearer 2 Earth radii. Neptune-like and waterworld compositions appear to be more likely.

    Even if you somehow manage to build a 32 Earth masses terrestrial without accreting any significant volatiles or hydrogen/helium component, you’ve still got the issue of outgassing. The planet should have a massive primordial atmosphere, and for a 32 Earth mass planet you are not going to lose much of that atmosphere at all. Given Kepler-22b receives about 10% more insolation than Earth, you need a much more moderate atmosphere or the greenhouse effect will be too large.

    It is interesting they use Kepler-18b as an example: from the Kepler-18 discovery paper:

    The inner, 3.5-day period planet Kepler-18b, is a super-Earth that requires a dominant mixture of water ice and rock, and no hydrogen/helium envelope. While the latter cannot be excluded simply on the basis of the planet’s mass and radius, the evaporation timescale for a primordial H/He envelope for a hot planet such as Kepler-18b is much shorter than the old age de-rived for the Kepler-18 system, and such a H/He envelope should not be present.

    i.e. they regard it as a supercritical steam planet, and such planets probably lack a well-defined surface. At the lower insolation received by Kepler-22b, the evaporation of the H/He layer is going to be less of an issue.

    The optimistic scenario is a primarily ice-rich planet. That ends up with an ocean of maybe 100km depth, above a mantle of high-pressure ices with a silicate core at the centre of the planet. Life needs more than just water, and the separation of the rocky material and the ocean by thousands of kilometres of ice does not bode well for mineral delivery to the ocean. Again it is questionable whether such a planet is really habitable. Plus you’d expect a substantial water vapour atmosphere, and in any case without a silicate/carbonate cycle acting as the stabilising feedback the models used for estimating the habitable zone are no longer valid.

  133. @ ^ andy : Thanks for that and your other informative comments here. :-)

    Please, would it be okay for me to quote those and you – with full attribution naturally – in an article I’m currently writing on the question of whether such “SuperEarths” are gas dwarfs or Rock giants? is there any way we can get in touch outside this blog that suits you? (I’m Steven Raine on facebook if that helps.)

    BTW. Interesting to note – as someone here did waay upthread if memory serves – that the size diagram comparison seems to put Kepler 22 b at roughly the same size vs Earth as Neptune is relative to Earth. Does anyone know of or is anyone able to make a direct three way comparison diagram showing the relative sizes of Kepler 22 b, Neptune and Earth together?

    @93. MTU :

    Also, please, can somebody, anybody, tell me the primary stars spectral type?

    Found it : G5 V yellow dwarf star – wikipedia entry for Kepler 22 b which is linked to my name. :-)

  134. Messier Tidy Upper

    @141. Joseph G : “Bahaha, I didn’t know that. At least they aren’t calling it Krypton or something And at least it’s making the headlines.”

    Yes, although I’m sometimes not sure whether to be happy about such discoveries getting such media coverage or frustrated by the misunderstandings and poor quality of some of the mainstream media reporting on it. Bit of both I guess. Although Letterman is actually pretty reasonable in having quite a lot of astronomical news on his show even if he does turn it all into comedy. David Letterman also been to see one of the last Space Shuttle launches and comes across to me as one of the better, smarter TV personalities on US (& obviously Aussie too) TV.

  135. sangos

    Ok so now science HAS proof that planets and other worlds exist…that can be deduced by the human mind btw. ‘Life on earth is unique’ – thats like the medieval
    belief that earth is the center of the universe! The main issue here being to develop the technology to get to those solar systems and planets. 22 billion years to get to Kepler 22b by shuttle!?…wow so obviously there has to be other smarter ways to travel…that should be the focus of NASA rather than verifying the obvious life ubiquitous in the universe. Come on thats simple logic no need to spend billions to verify.

  136. i do not think there is such a thing as alien life forms but i do believe that when the earth becomes too populated there will be possibilities of travelling to distant planets and inhabiting planets in our solar system to compensate for the world becoming a mass of too many people.

  137. bilal khan

    well i think…paradise may also be a planet….but it will be so bigger beyond our imaginations..as the day will be so long and same as night..so it means that their orbit will be bigger .and of course the gravity will be same as earth, but we cant go there using any rocket or technology, and to go there,,is just possible after death,, and through only way, of good deeds.. and we have to cross the bridge of sirat…which is narrower than a hair, for the people who have done bad deeds,,,but good people ..who have done good deeds…followed God’s path, and his messengers,, will go there by crossing the bridge of sirrat….so no need to spend 22 billion years…just use 60 years of your life….which NASA could not do….and no body can do..but just ourselves can do…………

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