Astronomers are discovering a lot of planets these days. The official count is 800+, with thousands of more candidates (unconfirmed but suspiciously planet-like).
Right now we give them alphabet soup names. Alpha Centauri Bb. HR 8799b (through HR8799 e). And of course, everyone’s favorite, 2MASS J04414489+2301513b.
These catalog names are useful, but less than public friendly. In science fiction we get Vulcan, Psychon, Arrakis, and other cool names. So why not in real life?
The folks at Uwingu asked themselves this very thing. Uwingu (pronounced oo-WIN-goo) is an astronomy and space startup company that’s looking to fund scientific research and exploration. I wrote an intro to Uwingu back when it was soliciting funds to get initially rolling (happily, that goal was met). The idea is to sell goods and services to space enthusiasts, and use the proceeds toward doing real science. The folks in charge are professional astronomers and space scientists at the tops of their fields, people like Alan Stern and Pamela Gay. Full disclosure: I am on the Board of Advisors for Uwingu, an unpaid position, but I’d write about it and support it anyway. These are top-notch scientists behind the project.
What does this have to do with the letter and number salad that is the current state of exoplanet names? As their first foray, the folks at Uwingu decided to let people create a suggested names list for these planets. For $0.99 a pop, you can submit a name you like to the database, and for another $0.99 you can vote for your favorite in the current list. I’ll note these names are not official – they are not assigned to specific planets, and only the International Astronomical Union can make these official (and mind you, they’re the ones who so elegantly handled the Pluto not being a planet issue (yes, that’s sarcasm)). But, these names will be seen by planetary astronomers, and eventually those planets are going to need names. Why not yours?
I think this is a fun idea. There are currently nearly a hundred names in the database as I write this, but it’s expected to grow rapidly. If you think there should be a Q’onoS, Abydos, or even Alderaan – in memoriam, of course – then head over to Uwingu.
OK, first, the planet: called PH-1, it’s bigger than Earth, about six times our radius, or about half the diameter of Jupiter. The mass isn’t well known, but may be as high as 170 times our own mass, though far more likely it’s closer to 20 – 50 times our mass. That makes it closer physically to Uranus and Saturn than Earth, so it’s likely a gas giant. It’s also hot, with a probable cloud-top temperature of 400+ Celsius (800+° F). Even if it has Earth-sized moons they’re likely to be too hot to be hospitable. And since it’s 5000 light years away, we’re not headed there any time soon, anyway.
But the more interesting thing about this planet is its host stars: PJK-1 orbits a binary star, two stars that orbit each other (like Tatooine, if you like). Six other planets are known to orbit binary stars, but PH-1 is even cooler: the binary star is itself orbited by another binary pair much farther out, making it the first planet found in a four-star system.
So we have two stars orbiting each other, orbited by a planet, and also orbited by two other stars which orbit each other. Yegads.
But it gets better yet. This planet was not found by professional astronomers! It was discovered by two amateurs who participate in the Planet Hunters program. This project was started by astronomers using the orbiting Kepler Observatory, designed to stare at 100,000 stars and look for dips in light from them as any potential planets orbiting them block their light. These transits show up in graphs of the stars’ brightnesses, and actually our human eyes and brain are pretty good at picking them out. Planet Hunters puts Kepler data online for anyone to go in and poke around.
The two citizen scientists, Kian Jek and Robert Gagliano, are listed as authors on the scientific paper recently published. I love this: the digital nature of these data make it far, far easier to analyze the science than it was in the past, and also easier to get the data out to people. Because of this, we have an explosive growth in these kinds of projects. Planet Hunters is great, but then so is Galaxy Zoo, Moon Mappers, Ice Hunters, and so many others. You can find several of these collected at the CosmoQuest website.
And a word about this new planet; this isn’t the first planet found by Planet Hunters, but it’s the first ever found in a quaternary star system. In the image here, the central binary is the big blob in the middle, and the second pair the elongated double-blob to the lower left. The planet is far too close to the middle stars to be seen here – its orbit is smaller than Earth’s around the Sun, far smaller than a pixel in this image at that distance.
The central binary is made up of a bluish star hotter and brighter than the Sun, and one that’s cooler, fainter, and redder. The second binary is made of one star much like the Sun, and another dinky red one. Their distance from the planet – about 150 billion kilometers – means they’d both still be very bright, with the brighter of the two almost as bright as the full Moon as seen from Earth. What a sight that would be! The second star would be hard to pick out in the glare of the other, but with binoculars you could spot it.
Not that anyone could, since the planet is hot enough to melt tin and assuming it had a solid surface to start with. Still though, it’s not hard to imagine a smaller planet orbiting that binary farther out, in a cooler, more life-friendly position. And we know such a planet exists; Kepler recently revealed a planet orbiting a binary star at the right spot to have liquid water as well. Like PH-1, that planet is probably a gas giant, but it might have big moons…
And this shows us once again that nature just loves to make planets, even ones in really weird places that at first may seem inhospitable for planet formation. But there it is.
Every time we find a strange planet like this, it fills me with hope that the ultimate goal of this work is close: finding an Earth-sized planet in the habitable zone of another star. We’re getting closer every day to that announcement, I think. In fact, I strongly suspect that planet is already sitting in the Kepler data, faint and hard to tease out, but just waiting to be found.
Go sign up for Planet Hunters. Maybe you’ll be the one to find it.
Image credits: Haven Giguere/Yale; Keck Observatory/Megan E. Schwamb et al.
- Two exoplanets discovered by "citizen scientists"
- YOU can find extrasolar planets
- Astronomers discover a wretched hive of scum and villainy (and the followup, Exoplanet news Part 4: More wretched hives of scum and villany)
- Kepler finds a planet in a binary star’s habitable zone
Oh, this is too cool: scientists have found a planet orbiting a binary star (a pair of stars in tight orbit around each other) that is at the right distance to have liquid water! Let me be clear: this planet is much bigger than Earth, and is likely to be a gas giant. So it’s not Earth-like, and probably not itself habitable.
But it might have moons…
[Note: this image is artwork based on the science. Click to tatooineneate.]
OK, first: Kepler is an orbiting telescope that has been staring at one spot in the sky for about three years now. It’s looking at about 100,000 stars. If these stars have planets, and the orbits of these planets are seen edge-on, then they will occasionally pass directly between us and their parent star blocking a little bit of the light. This is called a transit, and if the planet is big enough it can block enough light from the star to be detected by Kepler. So far, 77 planets have been confirmed using Kepler, and over 2000 more have been detected and are awaiting confirmation.
The new discovery deals with a binary star called Kepler-47. It’s about 5000 light years away, which is pretty far for a Kepler system – it’s faint at that distance. Still, the observations look very good, and the conclusions convincing to me.
One of the two stars is very Sun-like, about the same size, temperature, and brightness as our home star. The second is fainter, smaller, and cooler. They comprise an eclipsing binary: their orbit is seen edge-on from Earth, so they pass in front of each other as seen by us as they circle each other. Their orbit is pretty tight: they’re only about 13 million kilometers (8 million miles) from each other, and their orbit is just 7.5 days long.
Two planets were actually found orbiting the stars. Kepler-47b is about 3 times the diameter of the Earth. Its mass isn’t known, but it’s likely 7 – 10 times ours. It’s hot: the orbit is just 50 million km (30 million miles) out, closer than Mercury is to the Sun. It takes about 50 days to orbit.
The second planet, Kepler-47c, is the interesting one. It’s even bigger, 4 – 6 times Earth’s diameter, roughly the size of Uranus, and most likely 20 times our mass. Its orbit is almost exactly the same size as Earth’s, coincidentally, taking 300 days to orbit the binary (its year is shorter than ours because the two stars together have more mass, and therefore more gravity, than the Sun).
Taking into account the orbital size and the physical properties of the stars, the scientists have determined that the planet is at the right distance to be in the stars’ habitable zone: the distance where liquid water could exist on a solid body.
As I pointed out, the planet is probably a gas giant. But it could have moons – in fact, given our own solar system configuration, it seems likely. It’s not crazy to think that these moons, should they exist, might be habitable. That’s amazing.
These two new worlds put the roster of confirmed circumbinary planets (that is, planets orbiting binary stars) to six. And we only just started looking a few years ago! Given the number of stars observed and the planets found, and applying a little statistics, it seems entirely possible that there are millions of such planets in our Milky Way galaxy alone.
That’s right: millions of possible Tatooines just waiting to be found! And we may yet find them. Finding gas giant planets is far easier than finding their much smaller moons, but one of the goals of exoplanet astronomy is to improve the technology and the techniques to the point where such moons can be detected as well. It may take bigger telescopes and more time, but there is nothing stopping us except our will to do so.
Think of that: we can detect potential Earths around stars quadrillions of kilometers away! And all we have to do is want it enough.
[P.S. If you want to keep up with exoplanet news, there's a wonderful iPhone/iPad app called Exoplanet that has info, diagrams, and updates when new planets are found. I use it myself and really like it.]
Image credit: NASA/JPL-Caltech/T. Pyle
- Astronomers discover a wretched hive of scum and villainy
- Exoplanet news Part 4: More wretched hives of scum and villany
- No, that’s not a picture of a double sunset on Mars
- New study: 1/3 of Sun-like stars might have terrestrial planets in their habitable zones
[The article below was originally posted on the BBC Future blog, and was titled "Will we ever… find life elsewhere in the universe?" I'm reposting it here because, oddly, the BBC page is only readable for people outside the UK! It has to do with the BBC rights and all that. But they gave me permission to post it here, and since I thought it was fun and provocative, I figure y'all would like it. Enjoy.]
Will we ever… find life in space?
One of the reasons I love astronomy is that it doesn’t flinch from the big questions. And one of the biggest is: are we alone?
Another reason I love astronomy: it has a good shot at answering this question.
Even a few decades ago hard-headed realists pooh-poohed the idea of aliens. But times change, and so does science. We’ve accumulated enough data that makes the question less far-fetched than it once was, and I’m starting to think that the question isn’t "Will we find life?" but rather "Which method will find it first?"
There are three methods that, to me, are the front-runners for finding life on other worlds. And I have an idea as to which one may find it first.
Life on Mars?
The first method follows the principle that when you’re looking for something, it’s best to start close to home.
We know of one planet that has life: Earth. So it makes sense to look for other places with Earth-like conditions: that is, liquid water, oxygen in the air, nutrients for growth, and so on.
The most obvious place to look is Mars. At first glance it appears dry, cold and dead. But if you can see past that, things start to look up. The polar caps, for example, have lots of frozen water, and we’ve directly seen ice at lower latitudes on the Red Planet as well – meteorite impacts have left behind shiny craters, digging up fresh ice from below the surface.
Several Mars rovers and landers have uncovered tantalising evidence that liquid water might flow just beneath the surface, but we still lack any conclusive evidence. However, if you broaden your timescale a bit, there is excellent evidence that in the past – perhaps a billion years or so ago – our neighbouring planet had oceans of liquid water and thicker air. In fact, conditions were pretty good to develop life as we know it even before it popped up here on Earth.
It’s entirely possible that life got a toehold (or pseudopod hold) there long ago, and died out. If that’s the case, we may yet find fossils in the Martian rocks. Again, there’s no conclusive evidence yet, but we’ve literally barely scratched the surface there. Now that it has successfully landed on Mars, we have the exciting possibility that the plutonium-powered, car-sized Curiosity rover will soon use its on-board laser and other tools to crack open and examine rocks in the Gale Crater, which were laid down billions of years ago in the presence of liquid water.
And Mars isn’t the only possibility in our solar system. Liquid water exists inside Saturn’s moon Enceladus, where geysers of liquid water erupt from deep canyons at its south pole. Energised by the gravitational tug of the giant ringed planet itself, the interior of Enceladus may be a vast ocean of liquid water even while the surface is frozen over. That doesn’t guarantee we’ll ever find alien fish swimming that moon’s seas, of course. But it’s an interesting place to look.
Europa, a moon of Jupiter, almost certainly has an undersurface ocean as well. If you relax your constraints even more, Saturn’s moon Titan has lakes of liquid methane and ethane on its surface, too. The chemistry for life would be different there – it’s a rather chilly -180C on the surface – but it’s not impossible to suppose life might arise there too.
Finding out whether this is the case means getting up close and personal. We’re doing that for Mars; however, the likes of Europa and Enceladus may have to wait a decade or four.
But maybe we don’t have to go anywhere. Instead, we might be able to sit here and wait for alien beings (of whatever form) to message us.
This is pretty cool: astronomer Alex Parker took all the planet candidates found by the Kepler telescope – nearly 2300 planets in all – and made an animation showing what they would look like if they all orbited one star.
Dr. Parker had to do some scaling to make this work. For example, the actual size of each planet is known relative to its parent star, which he then scaled to fit the star shown in the animation. He scaled the distance from the star in a similar way. He describes it all on the page for the video.
I have to admit, it’s hard to know if there’s anything scientific we can learn from this. It’s fun to play with data, and it does often happen that by doing so you can see hidden relationships, things that aren’t obvious when displayed in normal ways (I’ve had that happen to me as well just playing with data – and Parker is very good indeed at playing with data; see Related Posts below for more cool stuff he’s done). That may very well turn out to be true in this case, or it may simply turn out to be an interesting demonstration. But as he points out, since this is animation was done to scale using all the Kepler planet candidates, one thing you see immediately is that there is always at least one transit going on! In other words, looking at all the Kepler host stars, no matter when you look, there are probably a dozen transits or more occurring at that moment.
That to me is actually shocking. I mean, it makes sense, and given some thought I would’ve realized it on my own. However, the context I always put this in is that just a few years ago we didn’t know of any transiting planets, and in fact for a while after the first were found a lot of astronomers scoffed at the idea. Now, though, the evidence is so overwhelming there is no doubt these transiting exoplanets exist.
And yet in all that time we didn’t know these planets existed, in all that time astronomers were looking for them and didn’t see them, in all that time some were found and other astronomers scoffed, there was never a time when there wasn’t a planet transiting a star.
And that’s just in the tiny patch of sky Kepler looks at; the entire sky is over 300 times bigger. So if there are a dozen or so transits going on in just the Kepler field, as Parker states, that means there are thousands of them going on in the sky even as you read this. Every day, all day, for millions and billions of years.
All those planets, perhaps millions of them, hidden in plain sight. All we needed to do was actually look for them.
So the usefulness of Parker’s animation is clear to me; its impact on me was profound. It reminded me once again that science evolves, and that my own biases – all our biases – must evolve with it. Otherwise, who knows what we’ll miss?
Tip o’ the dew shield to the Scientific American blog.
- Piano sonata in the key of Kepler-11 (music by Alex Parker based on planet orbits)
- Music of the spheres (more music by Alex Parker, this time based on supernovae)
- New study: 1/3 of Sun-like stars might have terrestrial planets in their habitable zones
- Motherlode of potential planets found: more than 1200 alien worlds!
One of my favorite aspects of astronomy is how it tackles the biggest questions we humans have. How did this all begin? What is the ultimate fate of the Universe?
Are we alone?
Oh, that last one. Such an interesting question, and one that for centuries has been essentially unanswerable due to a lack of solid data. But that’s changed very recently. We’ve started exploring other planets up close. We’ve been able to listen to potential signals from other civilizations. And we’ve begun to get a handle on how many habitable planets there might be in the Universe.
The BBC Future blog asked me to write up my thoughts on this for their clever series, "Will we ever…?", and so I did: "Will we ever… find life elsewhere in the universe?" is now online.
I’ll note this is an opinion piece, but it’s based on the best data I know about these three avenues of inquiry: physical inspection of other worlds in our solar system, listening for E.T., and observing planets around other stars. Given the current state-of-the-art, and where these programs are going, I predict which of these three I think will pay off first – assuming life is out there to find.
I won’t spoil it here. Go read the article!
[Note: In June, I also wrote a piece for them called Will We Ever Live on the Moon? which you may also enjoy.]
- Will we ever live on the Moon?
- 50 new worlds join the exoplanet list
- Success: SETI array back on track!
- Enceladus does and does not have a global ocean
- Huge lakes of water may exist under Europa’s ice
I was interviewed once again on the G4 TV program "Attack of the Show!" – I guess they didn’t learn their lesson the first time – where my pal Matt Mira (from Nerdist!) and I talked about planets around other stars, and whether Pluto is a planet or not.
Here’s the segment (you may need to refresh this page to load it):
I pretty much restated my case that I’ve been making about Pluto for quite some time: you can’t really define what a planet is, so the argument over whether Pluto is one or not is the wrong thing to be talking about. The fact that a fifth moon was recently found is irrelevant; "planet" is more of a concept than a defined object. Trying to draw firm borders around a fuzzy thing like this only guarantees more arguing and less light shed on the topic.
Anyway, it was a fun interview, and it’s always a good day when I can get one good zinger in, especially at Matt’s expense.
I’m very excited about all the news we’re getting of planets orbiting other stars. For Q&BA I got a good question about them: How many exoplanets are there?
[Note: the aspect ratio on this video is messed up a bit, like it was on the last one. I understand the problem now, but cannot fix it in this video. They should be back to normal next time!]
I wonder how many of the thousands of candidate planets known will turn out to be real? Probably most of them. And there are billion, hundreds of billions, of planets in our galaxy alone! How many of those are like Earth? Maybe soon we’ll know.
I don’t care if it’s a curse or not. We do live in interesting times.
I have an archive of Q&BA links and videos. Take a look and see if there are other ones that tickle your imagination.
- Q&BA: Which moon has the best chance for life?
- Q&BA: Can we build a space habitat?
- Q&BA: The Science of Science Fiction
- Q&BA: How does a gravity slingshot work?
- Q&BA: Why spend money on NASA?
- Q&BA: What happens if you are exposed to the vacuum of space?
HD 10180 is a star that’s nearly the Sun’s twin: it’s very close in mass, temperature, brightness, and even chemical content of our friendly neighborhood star. But in this case of stellar sibling rivalry, HD 10180 may have the upper hand: a new analysis of observations of the star indicate it may have nine planets!
In a new report accepted for publication in the journal Astronomy and Astrophysics, an astronomer re-analyzed data of the star taken with the High Accuracy Radial Velocity Planet
Searcher (HARPS), an exquisitely high-precision camera mounted on a 3.6 meter telescope in Chile. HARPS has been observing HD 10180 for years; the star is a mere 130 light years away, making it bright and easy to study. The observations look to see if the star exhibits a periodic shift in its light: a Doppler shift as planets circle it, tugging it one way and another.
Six clear Doppler shift signals were found in the original analysis: six planets, five of which have masses ranging from 12 – 25 times that of the Earth (making them more like Neptune than our own comfortable planet), and a sixth that was bigger yet, 65 times Earth’s mass (more like Saturn than Neptune). These planets orbit HD 10180 with periods of 5 – 2000 days. A seventh possible planet was detected, but the data weren’t strong enough to make a solid claim.
The new analysis looks at the old data in a different way, examining it using different statistical methods. Not only are the six planets seen in the new results, but the seventh is confirmed, as well as finding two additional planets in the data. If this result pans out, that means HD 10180 has nine planets, more than our solar system does!
The three additional planets have masses of 1.3, 1.9, and 5.1 times that of Earth, and orbit the star with periods (think of that as the planets’ years) of 1.2, 10, and 68 days, respectively.
Those first two are pretty firmly in the Earth-mass range, what astronomers call "super Earths". However, Earth-like they ain’t: they’d be cooked by the star. The first is only 3 million km (less than 2 million miles) from HD 10180, and the second barely any cooler at about 14 million km (8 million miles). This is much closer to the star than Mercury is to the Sun, and remember HD 10180 is very much like the Sun. If those planets are rocky, their surfaces are hot enough to melt tin, zinc, and on that inner planet, maybe even iron.
So yeah, not exactly a fun place to visit.
Well, this is some very welcome and happy news: NASA’s 2012 Senior Review for Operating Missions has recommended to NASA that eight of the nine operating space-based astrophysics missions be extended in funding through fiscal year 2016, and NASA has complied!
This really is great news! The missions extended through FY 2016 are Hubble, Chandra, Fermi, Planck, Suzaku, Swift, XMM-Newton, and Kepler. The exception is the infrared observatory Spitzer, which ran out of coolant a few years ago but is running in an extended "warm" phase, still able to do science. It will be extended through 2015, which is earlier than hoped, but it could be worse. The details are in the report issued by the Senior Review (PDF).
I’m very excited specifically about Swift — a gamma-ray burst mission that I worked on years ago, and which has been operating for more than 7 years so far. But I’m even more excited about Kepler. This is fantastic — it has found
hundreds dozens of planets orbiting other stars, and has thousands more candidates listed that await confirmation. The reason this extension is so great is that the longer Kepler looks, the more likely it is to find lower mass planets in longer orbits. Big, massive planets orbiting close to their stars are easy to find, but ones more like Earth are much tougher. Kepler is right on the thin hairy edge of being able to detect them now, and this extension means a much higher chance it will succeed.
I strongly suspect — based on what we’ve already seen from Kepler coupled with the statistics and physics of exoplanets — that the signal from an Earth-like planet orbiting a Sun-like star in the habitable zone is already in the data we’ve received. It may be very hard to tease out, though, so having even more data, years worth of extra data, is more than a boon. It’s like being given the key to a treasure chest.
So overall I’m pretty darn pleased with this. Given the semi-apocalyptic nature of the last budget news we heard about NASA, this is like an oasis in the desert. Congratulations to all the people involved with these missions, and I’m looking forward to many more years of great science from our orbiting fleet of observatories!
Tip o’ the lens cap to Travis Metcalfe for alerting me to this news.