Speaking of Neil Tyson, if you’re a fan of his you’ll be pleased to know that his show, Star Talk Radio, is now going to be part of the Nerdist Channel network! Thats actually a pretty big deal; Chris Hardwick has created this juggernaut of Nerdist and it reaches a lot of folks.
The new show is essentially a video version of the radio show. Chris interviewed Neil about it for The Nerdist website. If you’re curious what it’ll be like, here’s a video of a live Star Talk interview he did with several comedians (Hodgman! Schaal!) and Mike Massamino, a NASA astronaut:
Cool, eh? And maybe I’ll have more news about this soon, too. Superman isn’t the only guy who walks around in his underwear Neil has talked to.
I love it when kids get excited enough about science to go out and do something about it. That’s why I’m digging Jeffrey Tang – who’s 10 – because he created the Astronomy For Kids podcast, where he talks about different astronomical things. The first podcast went up in February 2012 ("The Solar System") and he’s done others on Stars, the Moon, Saturn, and gravity. They’re only a few minutes long, perfect for a kid to listen to, and the ones I listened to were accurate and covered the ground pretty well. They’re also interesting and fun!
If you have a kid who likes science, I bet they’ll like this podcast. And I can see these being played in schools, too. Who better to connect with kids than another kid?
[Today is Carl Sagan’s birthday, celebrated by lovers of science and rationality around the planet. I wrote the following post last year, but I think it’s still appropriate (and I updated his age). Happy birthday, Carl. It’s a darker cosmos without you, but we still walk with the candle you lit for us.]
If Carl Sagan were still alive, he’d be 78 years old today. Perhaps he wouldn’t have been overly concerned with arbitrary time measurements, especially when based on the fickle way we define a "year", but it’s human nature to look back at such integrally-divisible dates… and Carl was very much a student of human nature.
I’ve written about him so much in the past there’s not much I can add right now, so I thought I would simply embed a video for you to watch… but which one? Where James Randi eloquently and emotionally talks about his friendship with Carl? Or the wonderful first installment of Symphony of Science using my favorite quote by Carl? Or this amazing speech about how life seeks life?
But in the end, the choice is obvious. Carl Sagan’s essay, "Pale Blue Dot", will, I think, stand the test of time, and will deservedly be considered one of the greatest passages ever written in the English language.
Happy birthday to Doctor Carl Sagan, Professor of Astronomy, scientist, skeptic, muse, and – though he may not have thought of himself this way — poet.
I’ll leave you with this, something I wrote abut Carl a while back, when asked about what his greatest legacy is:
Sagan’s insight, his gift to us, is the knowledge that we all have the ability to examine the Universe with all the power of human curiosity, and we need not retreat from the answers we find.
Of all the amazing pictures returned from the moon by the Lunar Reconnaissance Orbiter – and I may include the Apollo landing sites among them – I think my favorites are the ones showing boulders that rolled down slopes.
Did I say rolled? I mean bounced!
[Click to enselenate.]
This shot from LRO shows the floor of crater Shuckburgh E, an impact crater about 9 km (~6 miles) across. The image shows a region about 655 meters (0.4 miles) across. The crater floor here is not level; it’s tilted up from left to right, and also has contours. Boulders dislodged for some reason (a seismic event, or a nearby impact) on the right have rolled down to the left… and some actually skipped along, bouncing and bounding as they did.
The two biggest trails are dashed, indicating the boulders had a bit of a rollicking time before coming to rest. You can see both boulders at the left of the trails, where they came to a stop. Note that the sunlight is coming from the bottom of this picture, which can play tricks on perspective. I see the boulders looking almost like craters and the skidding trails they left like little mounds. If you flip the picture over it may look better to you.
As always, pictures like this are a strong reminder that even on the Moon, where time stretches long and processes are slow, changes do occur. Maybe not often, and maybe not recently, but given enough time you have to think of the Moon as a dynamic place.
Image credit: NASA/GSFC/Arizona State University
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.
Well now, this is an interesting discovery: astronomers have found what looks like a "super-Earth" – a planet more massive than Earth but still smaller than a gas giant – orbiting a nearby star at the right distance to have liquid water on it! Given that, it might – might – be Earthlike.
This is pretty cool news. We’ve found planets like this before, but not very many! And it gets niftier: the planet has at least five siblings, all of which orbit its star closer than it does.
Now let me be clear: this is a planet candidate; it has not yet been confirmed. Reading the journal paper (PDF), though, the data look pretty good. It may yet turn out not to be real, but for the purpose of this blog post I’ll just put this caveat here, call it a planet from here on out, and fairly warned be ye, says I.
The star is called HD 40307, and it’s a bit over 40 light years away (pretty close in galactic standards, but I wouldn’t want to walk there). It’s a K2.5 dwarf, which means it’s cooler, dimmer, and smaller than the Sun, but not by much. In other words, it’s reasonably Sun-like. By coincidence, it appears ot be about the age as the Sun, too: 4.5 billion years. It was observed using HARPS, the High Accuracy Radial Velocity Planet Searcher (I know, it should be HARVPS, but that’s harvd to pronounce). This is an extremely sensitive instrument that looks for changes in the starlight as a planet (or planets) orbits a star. The gravity of the star causes the planet to orbit it, but the planet has gravity too. As it circles the star, the star makes a littler circle too (I like to think of it as two kids, one bigger than the other, clasping hands and swinging each other around; the lighter kid makes a big circle and the bigger kid makes a smaller circle). As the star makes its circle, half the time it’s approaching us and half the time it’s receding. This means its light is Doppler shifted, the same effect that makes a motorcycle engine drop in pitch as it passes you.
Massive planets tug on their star harder, so they’re easier to find this way. Also, a planet closer in has a shorter orbit, so you don’t have to look as long to find it. But in the end, by measuring just how the star is Doppler shifted, you can get the mass and orbital period of the planet. Or planets.
In this case, HD 40307 was originally observed a little while back by HARPS, and three planets were found. But the data are public, so a team of astronomers grabbed it and used a more sensitive method to extract any planetary signatures from the data. They found the three previously-seen planets easily enough, but also found three more! One of them is from a planet that has (at least) seven times the mass of the Earth, and orbits with a 198 day period. Called HD 40307g (planets are named after their host star, with a lower case letter after starting with b), it’s in the "super-Earth" range: more massive than Earth, but less than, say Neptune (which is 17 times our mass).
We don’t know how big the planet is, unfortunately. It might be dense and only a little bigger than Earth, or it could be big and puffy. But if its density and size are just so, it could easily have about the same surface gravity as Earth – that is, if you stood on it, you’d weight the same as you do now!
But the very interesting thing is that it orbits the star at a distance of about 90 million kilometers (55 million miles) – closer to its star than is is to the Sun… but that’s good! The star is fainter and cooler than the Sun, remember. In fact, at this distance, the planet is right in the star’s "habitable zone", where the temperature is about right for liquid water to exist!
That’s exciting because of the prospect for life. Now, whenever I mention this I hear from people who get all huffy and say that we don’t know you need water for life. That’s true, but look around. Water is common on Earth, and here we are. We don’t know that you need water for life, but we do know that water is abundant and we need it. We don’t know for sure of any other ways for life to form, so it makes sense to look where we understand things best. And that means liquid water.
Here’s a diagram of the system as compared to our own:
Note the scales are a bit different, so that the habitable zones of the Sun and of HD 40307 line up better (remember, HD 40307g is actually closer to its star than Earth is to the Sun – an AU is the distance of the Earth to the Sun, so HD 40307 is about 0.6 AU from its star). What makes me smile is that the new planet is actually better situated in its "Goldilocks Zone" than Earth is! That’s good news, actually: the orbit may be elliptical (the shape can’t be determined from the types of observations made) but still stay entirely in the star’s habitable zone.
And take a look at the system: the other planets all orbit closer to the star! We only have two inside Earth’s orbit in our solar system… but all five of HD 40307’s planets would fit comfortably inside Mercury’s orbit. Amazing.
So this planet – if it checks out as being real – is one of only a few we’ve found in the right location for life as we know it. And some of those we’ve found already are gas giants (though they could have big moons where life could arise). So what this shows us is that the Earth isn’t as out of the ordinary as we may have once thought: nature has lots of ways of putting planets the right distances from their stars for life.
We’re edging closer all the time to finding that big goal: an Earth-sized, Earth-like planet orbiting a Sun-like star at the right distance for life. This planet is a actually a pretty good fit, but we just don’t know enough about it (primarily its size). So I’m still waiting. And given the numbers of stars we’ve observed, and the number of planets we found, as always I have to ask: has Earth II already been observed, and the data just waiting to be uncovered?
Image credits: ESO/M. Kornmesser; Tuomi et al.
– ALPHA CENTAURI HAS A PLANET!
– Kepler confirms first planet found in the habitable zone of a Sun-like star!
– A nearby star may have more planets than we do
– Exoplanet in a triple star system, smack dab in the habitable zone
– Super-Earth exoplanet likely to be a waterworld
Seeing the International Space Station pass overhead is pretty cool. It glides soundlessly across the sky, getting brighter as it gets closer to you, whizzing by hundreds of kilometers above your head at 8 kilometers per second.
I usually go to Heavens-Above when I think of it to check when the next few passes will be. But wouldn’t it be nice if you get a text or email letting you know that a pass is about to happen?
NASA has set up a service to do just that: Spot The Station. You can give it your email or phone number, your location, and whether you’d like to see evening passes, morning ones, or both (because the station is lit by the Sun, you can only see it just after sunset or before sunrise).
That’s all there is to it. The next time the station is going to be visible from your location, NASA will send you a note. They also have a page describing what the message means, so you can go outside and figure out not just when to look, but where.
I’ll note there’s another service that does this as well: Twisst, which uses Twitter to let you know about good station passes at your location. It would be fun to compare them, actually. And useful, because they may have different criteria for what constitutes a good viewing opportunity. If you want to see the station, it might pay to hedge your bet.
And don’t forget to try to take a picture! The shot above is one I took a few years ago with nothing more than an off-the-shelf point-and-shoot camera set up on a tripod in my back yard. There are two streaks because one (on the right) is the station, and the other is the Space Shuttle Atlantis! I can guarantee you can’t get that shot again, but we do send other spacecraft to the station, so if you time it right you might get something like this. If you don’t try, it’s a sure thing you never will, so give it a shot!
– Watch the skies for the Shuttle and ISS
– And I saw a star rising in… the WEST?
– SERIOUSLY jaw-dropping pictures of Endeavour and the ISS!
– Ridiculously awesome pic of Discovery and the ISS taken from the ground!
Oh my, another lovely night sky (and landscape!) time lapse video; this time from Alessandro Della Bella, and called Helvetia’s Dream:
[Make sure you set it to hi-def and make it full screen.]
I love the opening shot! Unless it was just digitally zoomed, it must have taken some planning; you have to know just where the Moon is going to rise to catch it that accurately.
A couple of other things to watch for, too:
At about 45 seconds in, a bright meteor leaves a long persistent train, a glowing trail that gets blown away by the thin but rapid winds 100 kilometers above the Earth’s surface. I actually gasped when I saw that!
At 1:30 you see the stars of Orion setting behind the Matterhorn, zoomed in. The big bright pink blob is the famed Orion Nebula, but just above it is the star Alnitak with a bit of nebulosity around it; the bright patch is the Flame nebula, and barely visible is the much fainter but iconic Horsehead Nebula.
I also love how the clouds – more like fog – flow through the valley. The study of how things flow is called hydrodynamics, and physicists use the word "fluid" to describe the stuff that’s flowing. In common vernacular that means liquid ("Have you been drinking enough fluids?") but in science air is a fluid. So is the thin gas in a nebula, since it can carry sound waves and be shaped by supersonic flow.
Whenever a doctor asks me if I’ve been taking my fluids, I always want to respond, "WHAT? And ionize my cardiovascular system?!"
I’ve never had the guts.
Anyway, one more thing: the Moon setting at the end is actually not full! The long exposure times makes it look that way, but when it nears the horizon you can see it’s really a thin crescent, but the dark part of the Moon is being illuminated by Earthshine: light from the Earth itself softly illuminating the nighttime moonscape, which is then reflected back to us.
There’s poetry in the heavens, if you know where to look.
Tip o’ the lens cap to MichaelPeterson on Twitter.
The story of Superman is so well known that I hardly need go into detail. But in case you’re some sort of commie, the idea is that he was born on the planet Krypton orbiting a far away red star, and sent to Earth while still a baby by his parents as their home planet exploded around them. Our yellow Sun somehow gives Kal-El superpowers, and he goes on to star in a series of increasingly poorly-made movies*.
I’ve often wondered exactly what kind of star Krypton orbited and where it was. Up until now all we’ve known is that it was red, and red stars come in many flavors, from dinky red dwarfs with a tenth the mass of the Sun up to massive supergiants like Betelgeuse which outweigh the Sun by dozens of times (I’ll note that a deleted scene in "Superman Returns" indicates it’s a red supergiant).
Well, that’s about to change. DC comics is releasing a new book this week – Action Comics Superman #14 – that finally reveals the answer to this stellar question. And they picked a special guest to reveal it: my old friend Neil Tyson.
Actually, Neil did more than just appear in the comic: he was approached by DC to find a good star to fit the story. Red supergiants don’t work; they explode as supernovae when they are too young to have an advanced civilization rise on any orbiting planets. Red giants aren’t a great fit either; they can be old, but none is at the right distance to match the storyline. It would have to be a red dwarf: there are lots of them, they can be very old, and some are close enough to fit the plot.
I won’t keep you in suspense: the star is LHS 2520, a red dwarf in the southern constellation of Corvus (at the center of the picture here). It’s an M3.5 dwarf, meaning it has about a quarter of the Sun’s mass, a third its diameter, roughly half the Sun’s temperature, and a luminosity of a mere 1% of our Sun’s. It’s only 27 light years away – very close on the scale of the galaxy – but such a dim bulb you need a telescope to see it at all (for any astronomers out there, the coordinates are RA: 12h 10m 5.77s, Dec: -15° 4m 17.9 s).
Which brings us back to the Superman story. I was sent an advance copy, and it’s actually a clever tale, with some relatively solid science in it. I won’t spoil it, but apparently Superman comes to visit the Hayden Planetarium in New York City (where Neil is the director) every 382 days, which happens to be the period of Krypton around the star (known as Rao in the comic canon). Although it’s not said explicitly in the story, it sounds like they try to observe Krypton when it’s at the point in its orbit where it appears farthest from its star, reducing the glare and making it easier to spot†.
As for the major plot point of the story, I won’t reveal it. But I’ll give you a hint: Superman is about 27 years old. PLEASE don’t leave any guesses in the comments below until a few days after the issue is out. I want to avoid spoiling it for any other readers.
Being a dork, I have to comment on some of the science in the story, though. Given the mass of a star and the period of a planet orbiting it, you can find the distance between the two. Doing the math (I’m a dork, remember?) I find the distance of Krypton to its Sun is about 100 million kilometers, somewhat closer than Earth is to the Sun (150 million kilometers).
But remember, Rao is a dim red dwarf! It’s so cool and faint that even at that closer orbital distance, Krypton would be a chilly world. Even if the planet is black as soot (and thereby absorbing all the heat falling on it from Rao) its temperature is still something like -170° Celsius – about -270° F! [If you’re curious, I outline how to calculate this on the Bad Astronomy website.] At that temperature oxygen and nitrogen are still gases – barely – but it’s way below the freezing point of water. And if it’s not black, but instead snowy and white, the temperature will be even lower.
So Krypton maybe isn’t the best place for life to arise… still, there are ways out of this. Maybe either the Kryptonians migrated there (they couldn’t find a warmer planet?) or there’s something else going on. If it’s really volcanic then greenhouse gases could be prevalent, raising the temperature. Possibly the planet’s interior is still warm from heat leftover from its formation… or maybe whatever made it warm enough to be habitable also led to its destruction. Comic book science can be pretty ironic.
[DC comics: call me! I have ideas.]
I also feel obligated to note that in the comic, they made the planet look much larger than the star. That doesn’t work; the two are so far away it doesn’t matter if Krypton was on Rao’s near or far side; it would have to appear smaller than the star. We know Krypton is not a gas giant, so it can’t be much more than a few times Earth’s size. Even compared to a red dwarf that’s pretty small.
Still, it does make for a dramatic series of panels, and I’m always willing to let art trump science if need be. And this really is a pretty nifty story.
The issue comes out on November 7, and I’ll be heading over to my local comic store (Time Warp) to pick up a copy. Next time I see Neil maybe I’ll get him to sign it. It’s not too often I get to do that with someone who knows Superman.
Image credits: DC Comics; Digitized Sky Survey/NASA/Skyview
* I love – LOVE – the 1978 Superman movie, and I still to this day listen to the soundtrack, so you can argue with me over this, but you will be wrong.
† This actually happens twice per orbit, when it’s on either side of its star. That means the orbital period is actually twice 382 days, or well over two years… and as you’ll see, that puts it farther from its star, making things worse.
So there’s this comet named 168P/Hergenrother. It’s one of a bazillion such iceballs orbiting the Sun, but this one turns out to be more interesting than most. For one thing, it has a short period, orbiting the Sun once every 6.8 years or so. Its orbit goes out to about that of Jupiter’s, and reaches down into the inner solar system about as far as Mars. It never gets closer than about 80 million kilometers (50 million miles) to us, so it’s usually relatively faint, and you need a big ‘scope to observe it.
It was discovered in 1998, and made a second pass down our way in 2005. This year, 2012, it came by again, and folks around the world observed it as they do any comet. But then, in September, it gave us a surprise. A big one. Lots of observers were reporting that practically overnight the comet grew hugely in brightness, getting as much as 700 times brighter than expected! Not only that, but observations showed the shape of the comet had changed, going from fairly point-like to much fuzzier.
That could mean only one thing. The comet was breaking up.
The picture above is from the Faulkes Telescope North, located on the Hawaiian observatory on Haleakala. It’s a composite of lots of separate exposures that were added together; you can see the stars are trailed (actually stippled; each exposure was short but then shifted to line up on the comet). The comet is the bright fuzzy blob in the upper right, and if you look just below the main part you can see a second fuzzy blob, much fainter.
That’s proof positive the comet calved, or had a big chunk break off. In fact, observations using the huge Gemini telescope show that the main body has broken up into at least four pieces! So what does this mean?
First, don’t panic. We’ve seen this happen to comets before, and this one is so far away from us we’re in no danger at all. It literally cannot get near us.
Second, it’s very interesting scientifically. Comets are basically big frozen snowballs peppered with rock. Imagine scooping up a handful of gravel and snow and then packing into a loose ball. That’s a comet, if your snowball is several kilometers across and the ice is actually frozen water and carbon dioxide. When they are far from the Sun comets stay frozen and are exceedingly dim. When they get closer, the ice goes directly to a gas (called sublimation), and escapes from the solid part (called the nucleus). It expands and can form a big fuzzy head around the solid nucleus that can be tens of thousands of kilometers across, bigger than planets! This is also what gets blown back by the solar wind (and the pressure of sunlight) to form the tail(s) of the comet.
This means that every time a comet gets closer to the Sun and starts to sublimate, it dies a little bit. Material leaves the comet and never comes back. But that ice is what holds the comet together! So sometimes enough ice turns into a gas and escapes that the comet gets substantially weaker, and big chunks of it can dislodge, falling away. That’s what appears to have happened to Hergenrother.
While we’ve seen this before with other comets, it’s not like it happens every day, so any chance to see this occur is fascinating. In 2006 we watched as comet 73P/Schwassmann-Wachmann 3 literally disintegrated. Even more amazing, in 2007 the run-of-the-mill comet 17P/Holmes suddenly erupted, getting hugely brighter, and a huge shell of dust was seen to be expanding around it. Now we think Holmes collided with a small asteroid, and the violence of the event blasted off the material. I saw Holmes with own eyes when this happened, and even though it was past the orbit of Mars, the shell of dust was easily visible to the naked eye. It was awesome.
No two comets are ever really alike. They have different sizes, shapes, compositions, and orbits. And each will behave slightly differently as they round the Sun and head back into deep space. If there’s a lesson from Hergenrother, it’s this: it’s always a good idea to keep an eye on everything in the sky. Just because something looks routine now doesn’t mean it won’t try to pull a fast one later.
Tip o’ the Whipple Shield to AsteroidWatch NickAstronomer. Image credits: Hergenrother: LCOGT/Giovanni Sostero, Nick Howes, Alison Tripp & Ernesto Guido; Holmes: Tamas Ladanyi