Gallery: The Red Planet and the Comet
Yesterday, Oct. 19, at approximately 18:30 UTC, Mars got buzzed by a comet.
The comet, named C/2013 A1 (Siding Spring), passed just 130,000 km (80,000 miles) above the surface of Mars, the closest cometary encounter with a terrestrial planet ever seen (the adjective is because Jupiter has been hit by several comets and asteroids in the past few years).
Siding Spring is an Oort cloud comet, meaning it came from the very remotest regions of the solar system, almost certainly plunging into the inner system for the first time after billions of years in the dark. It chose quite a path for its first trip here! Mind you, the comet got three times closer to Mars than the Moon is to Earth. This was a close shave indeed.
NASA and other space agencies took precautions, moving their orbiting probes to the far side of the Red Planet during closest approach, while the rovers were pretty much on their own. Happily, they all appear to be fine, even after the comet dropped tons of material into the atmosphere at dozens of kilometers per second.
We’re still awaiting images taken from those probes, but in the meantime, quite a few dramatic pictures were taken from Earth. Here are a few of the ones I like best…
Persistence Pays Off: The Smoking Trail of a Shooting Star
On Oct. 16, 2014, a redditor by the handle -545- was camping at the Ashton-Wildwood County Park in Iowa. He spotted a clearing in the trees near his campsite which framed a part of the sky, so he set his camera up to take a series of 10-second exposures in the hopes of getting good footage for a time-lapse video.
What he got was better than good: He caught a bright meteor that left a persistent train, a trail of glowing vapor that lasted for quite some time:
That’s pretty amazing timing and framing. The meteor appeared right in the middle of the hole in the trees, and the meteor must have appeared very early in the 10-second exposure that first shows it; you can already see some of the vapor trail it left behind. For those keeping track at home: The brightish star to the right of the meteor is Gamma Triangulum, the star above the middle of the streak is 1 Tri, and the little diamond to the left is 12 and 13 Tri with two fainter stars (HD15226 and HD15326); it took me a while poring over my planetarium software to nail this down!
This sort of event is pretty rare, though not unheard of (I have several blog posts showing them; see Related Posts below). A meteor is just a small chunk of rock, ice, or metal that’s orbiting the Sun, and the Earth gets in its way. As it plunges through our atmosphere at high speed, it violently compresses the air ahead of it, heating it. This in turn heats the meteoroid (the solid bit of interplanetary debris; as it burns up it’s called a meteor, and if it hits the ground it’s a meteorite), which glows and leaves behind the bright but generally short-lived trail.
But the event can also ionize the air, stripping electrons from their parent molecules. As the electrons recombine, they give off a bit of light. This is called a persistent train, and some have been known to last for many minutes. The train is roughly 80–100 km above the ground, and upper atmosphere winds blow it into twisting, eerie shapes.
-545- really nailed this one! You might think he was lucky, but it’s not luck. It’s persistence. Events like this happen, and if you go outside enough, watch the sky long enough, take enough pictures … you’ll wind up with something amazing.
And if you do see a bright meteor (sometimes called a fireball or bolide), make sure you note your time, location, and the direction you saw it. Then you can report it to the American Meteor Society, which collects these data. Sometimes this can help recover meteorites if there are any!
Tip o’ the Whipple Shield to reddit, and the many, many people who sent this my way.
Mars and the Comet: The Countdown
On Sunday, Oct. 19, 2014, at about 18:30 UTC (14:30 Eastern), Mars will experience a very close encounter with a comet.
The comet C/2013 A1 (Siding Spring) will pass just about 130,000 kilometers (80,000 miles) from the surface of Mars. There is no danger of an impact, but the planet will pass through part of the comet's tail (which is composed of gas molecules and dust).
NASA and other space agencies have taken precautions to make sure the spacecraft at Mars won't be hurt, but they're also hoping to capitalize on this unprecedented opportunity to see a comet VERY up close and personal. I'm not sure just when we'll start seeing data from them, but I highly recommend keeping an eye on Emily Lakdawalla's blog page and her Twitter feed. She is really great about staying up to date and relaying accurate information as soon as she has it.
I'll try to keep up as well, and if anything interesting happens I'll let you know. It's generally a good bet to follow me on Twitter too, as I'll be linking to things there, including news from other folks as it's confirmed.
Update, Oct. 18 at 15:30 UTC: The Virtual Telescope Network will be streaming images of the comet and Mars live starting at 16:45 UTC Sunday.
Update 2, Oct. 18 at 19:00 UTC: D'oh! I forgot to say: Also follow Karl Battams on Twitter, and keep your finger on the refresh button of the Coordinated Investigation of Comets page. Tons of info there!
Update 3, Oct. 19 at 18:00 UTC:
ESA is holding a live webcast about the comet encounter. Due to technical difficulties, the ESA live 'cast has been moved to a Google Hangout.
A thought: The NASA comet page says the coma (the big fuzzy cloud of gas surrounding the solid nucleus of the comet) is about 20,000 km across. At closest approach, that means that if you were standing on Mars, the comet would appear to be over 8° across! That means that if you have a big hand, you could just barely block it with your upraised fist.
That's astonishing. What a view that would be! And while the astronomer part of my brain is envious and wishes we could see something like that from Earth, the human part of my brain is screaming obscenities at the astronomer part of my brain. In real life, it's probably best comets keep their distance from us.
Figuratively Shiny: A Firefly Video
Perhaps now that cavity can be filled in a little bit. The company Lootcrate, with producer and director Julian Higgins, has created a fan-made short video called “The Verse,” about a different crew in the same universe as that of the good ship Serenity. Here’s the thing: It’s really, really good. Seriously. If you’re a Browncoat, you need to watch this right now.
See? Told ya. And I’m not the only one who thinks so. Given the time span since the series ended, a reunion show seems pretty unlikely. But I could get into this new crew, I think. And hey, did I spy Vic Mignogna, who plays Jim Kirk in Star Trek Continues, another fan-made production? That must’ve been on purpose.
It’s pretty amazing what dedicated and talented fans can do. And we’re seeing more and better Web series all the time, too. This Internet thing may just have a future to it.
*You kids get off my ‘verse!
Literally Shiny: A Firefly Video
After living practically my whole life on the East Coast, one of the things I didn’t count on when I moved west was the lack of fireflies. They were such a ubiquitous phenomenon, such a part of the environment, that it never occurred to me that they might not be everywhere in the States.
But they don’t live in California, where I lived for seven years, or in Colorado, which I’ve called home for the better part of a decade now. I miss them.
But it helps a lot to see this lovely time-lapse (kinda) video of fireflies, shot by Vincent Brady.
Nice. And he used a clever technique for some of the effects. A video is really just a series of still images played rapidly, fooling your brain in to seeing motion. Brady took thousands of still images and strung them together to make the video. For some, he let the frames fade in, linger, then fade out again. The end result is you see the light from the fireflies persist for a few seconds before dimming, with insects at all different distances creating a stop-motion-like dance.
Incidentally, the compound that generates the light is called luciferin (Lucifer was the mythological bringer of light), which is the same class of substrate used by dinoflagellates to glow. I spent an evening kayaking on a lake filled with such protists, and watching the blue sparks fly every time I put the oar in the water was magical.
Nature is amazing. It’s wonderful what happens if you take hydrogen, helium, and a splash of lithium, and let them mix for a few billion years.
Tip of the adenosine triphosphate to Boing Boing.
Ice to See You
The last place in the solar system you’d expect to find ice (except maybe on the Sun, duh) is Mercury. Rocky, barren, airless, and very, very hot, Mercury doesn’t sound like the ideal location for storing vast quantities of frozen water.
But in the 1990s evidence started coming in that perhaps Mercury was holding a surprise. At its north pole are deep craters, and because of their high latitude, the low Sun never reaches the crater floors. They’re permanently dark, and because of that they’re very cold. Cold enough to hold on to any water that might have found its way there (presumably through water-bearing asteroid and comet impacts).
The first evidence was from radar observations; those craters were found to be very radar-reflective, which suggested ice, though other materials were possible. But over the years more clues arrived, and when the MESSENGER spacecraft began orbiting the tiny world, the idea of polar water got kick-started. Neutrons were reflected from the crater floors, which indicated the presence of hydrogen (water molecules have two hydrogen atoms each and are very good at reflecting incoming neutrons). MESSENGER has an infrared laser altimeter on board (it uses timing of pulses of light to measure its height off the surface and get topological data), and the craters were again found to be very reflective, which is consistent with ice.
And now we have further, very striking data: Pictures taken of the floor of the crater Prokofiev* show that some of the surface itself is a bit brighter, a bit shinier, than surrounding material. Not only that, but the brighter regions correspond extremely well with what has been found before.
The picture here shows the data. The upper left (A) is from radar observations; the blue circle is the crater rim, the red region is where it’s permanently shadowed—the Sun never shines there—and the yellow is where the radar reflections were brighter than normal. The bottom left (B) shows where the laser altimeter found unusually bright material. On the right (C and D) are the images taken by MESSENGER’s visible light camera. They are the same area and have the same orientation but were taken when the Sun was shining from different directions. The brighter landscape there is clearly visible on the right, and as you can see matches the other observations right on the nose.
The scientists found similar results in other craters even farther north on Mercury (Prokofiev is about 5° south of the north pole, and is 112 kilometers, or 70 miles, across). The amount of ice estimated to be trapped in the floors of these craters is 10 billion to one trillion tons—a huge amount. As the paper points out, that’s about the volume of Lake Ontario.
Personally, I find this to be pretty convincing. It's not a 100 percent lock, but the evidence is getting to be pretty hard to deny.
The ice is likely to be young, too. Impacts, ultraviolet light breaking down the molecules, and other weathering could darken, bury, or eradicate the ice on a timescale of tens or hundreds of millions of years, so it’s likely this deposit hasn’t been around since the early solar system (astronomers define "young" differently than normal humans).
In practical terms, I have a hard time seeing us sending folks to Mercury, setting up a base at its poles, and taking long hot baths using native water any time soon. But this shows that even now, with our huge telescopes, advanced hardware, and robot probes peeking and poking into every corner of the solar system, there’s still a lot to learn about our neighborhood, and a whole lot of surprises waiting to be unwrapped.
We also have similar evidence of water at the Moon’s poles, too, buried under and mixed into the rock at the floors of eternally darkened craters. I don’t have a hard time seeing us going there at all. There could be enough water on the Moon to support a colony for quite some time. That is something I would very dearly love to know more about.
*Craters on Mercury are named after artists: composers, painters, writers, and so on. Sergei Prokofiev was a Russian romantic composer, and one of my favorites; his Fifth Symphony is an astonishing work. It pleases me that such an important discovery has been found in his namesake.
To Pluto … AND BEYOND!
In July of 2015, the New Horizons space probe will whiz past Pluto, traveling at 40,000 kilometers per hour. For several weeks before and after the close flyby—it’ll pass within 10,000 km above the tiny world’s surface—it will examine Pluto, its moons, and the environment around it.
But this is not an orbiter, or a lander. Pluto is 5 billion kilometers from Earth, and the only way to get a probe there in any decent amount of time was to strip it down as light as possible and fling it as hard as possible, getting it moving so rapidly it could traverse the yawning chasm between us and Pluto as quickly as possible (with a boost from Jupiter along the way).
This is a fast flyby, with no slowing down. Once New Horizons is gone, it’s gone.
Except the solar system hardly ends at Pluto. There’s a vast collection of objects out there in the dark: cold, icy worldlets called Kuiper Belt objects. There are millions of them, relics from the formation of the solar system itself, and largely unchanged for billions of years. Getting a look at one up close is a very tempting goal.
The New Horizons team started a search in 2011 using large ground-based telescopes, and while they found dozens of these KBOs, none was near enough to the probe’s trajectory to investigate. Remember, space is vast and empty—that’s why we call it “space”—and while there may be millions of KBOs, they’re still spread pretty thin out there.
So they turned to Hubble. Narrowing the search but able to detect fainter objects, Hubble was the last hope … and it paid off. They found three potential targets, each over a billion kilometers farther out than Pluto. One, called (for now) PT1 (guess why) should be easy to reach given New Horizons’ present path and fuel supply. Its size is not clear, but based on its brightness and likely surface reflectivity it’s probably more than 30 km (20 miles) in diameter. New Horizons would fly past it in January 2019.
Not that this is a given. Ostensibly, the probe’s mission is over once it flies past Pluto. The team will have to ask NASA for an extension, and those aren’t given out lightly. However, I think this is a very worthy goal. We’ve never seen a pristine KBO up close, just moons we think used to be KBOs but were captured by planets, like Neptune’s Triton and Saturn’s Phoebe. These are likely to have changed over time since they became enthralled to their parent planets, so finding a KBO in its natural habitat is a very exciting idea.
Also, politically, I think it’s a feather in NASA’s cap to be able to retool a space mission to do something more than it was originally designed to do. If things go well at Pluto, and we expect they will, the public will be pretty excited about the mission; folks seem to have a special place in their hearts for the little ice ball. Leveraging that would be pretty smart on NASA’s part.
For details on the search and how they planned this flyby of a KBO, go read Emily Lakdawalla’s write-up. She has (as usual) an excellent and very thorough article about it.
I’m excited about this. I’ve been interested in KBOs since my own days with Hubble; I spent a little bit of time looking into using Hubble to search for objects very far from the Sun, and unfortunately given the logistics at the time (back in the late 1990s) it wouldn’t have really worked. But the cameras are better now, our techniques have improved, and it’s really gratifying to see this getting done. And if PT1 does rate a flyby, we’ll see that little blip in the Hubble image turn into a place, a small but perfect example of what our solar system is like, in the far reaches of nearly—but not quite—empty space.
Evidence for Evolution, Stated Clearly
Here at BA Central, we’re* big supporters of evidence-based reality and using science as a way to collect and weigh that evidence.
The problem is that a lot of science isn’t well understood by the public for a large number of reasons; some folks blame the education system, which certainly has issues, though perhaps a much larger and more endemic problem is ideology, which gets into your brain and acts like a bouncer at a bar, only letting through ideas that are on a preconceived checklist.
Evolution is an obvious example. Despite being one of the fundamental bases for all of modern biology (along with things like molecular biology, genetics, and so on), it is routinely and falsely attacked by many. A lot of scientists and science communicators scratch their heads over that; what’s hard for us on this side of reality to understand is how anyone can ignore the vast mountains of evidence supporting evolution.
My friend Zach Weiner put his finger right on it, in my opinion, when he wrote this:
The more I read from creationists, the more I think they're not anti-evolution. They're anti-some crazy version of it their pastor taught.— Sexy Z. Weinersmith (@ZachWeiner) April 4, 2012
I think that’s it; the folks who don’t “believe” in evolution are the ones disseminating a weird, wrong, strawman version of it.
While there’s not a huge amount I can do about that, what I can do is try to make correct, easy-to-understand information about evolution available. I’ve done it before and it seemed to work out well.
So I’m pleased to send y’all to a great website called “Stated Clearly,” where artist and science communicator Jon Perry has created a series of wonderful videos where information about and evidence for evolution is, well, stated clearly.
The video “What Is the Evidence for Evolution?” is fantastic. It’s simple without being oversimplified, and it gives clear examples that can be followed easily even if you’re not all that familiar with the science.
That last part is critical, because, as Zach pointed out, the ones fighting tooth and nail against evolution are almost assuredly not that familiar with it. If they were, we wouldn’t be spending our time defending evolution. We’d be spending more money investigating it.
Perry has assembled quite a team to create these videos (including, I was pleased to see, Rosemary Mosco, a field naturalist, science communicator, and friend-of-a-friend). There are articles there as well expounding further on some of the themes.
The evidence video was sponsored wholly through Kickstarter, which is great, since it costs a fair bit to put together something like this. If you have any extra filthy lucre lying around, you should consider throwing it their way. They’ll have merchandise soon, and I’ll be keeping an eye out for that. I want a shirt of Darwin riding an Archaeopteryx.
Tip o’ the telomere to Raw Story.
I Got Shot in the Asteroid
Once again this year I have talked the talk and walked the walk: I got my annual flu shot.
I was hoping you’d see more of my asteroid tattoo in this picture, but what the heck. It gets the job done. As usual, the shot was painless, inexpensive, and should help my immune system do what it’s meant to do.
Flu shots are important. Everybody’s freaking out about Ebola right now, but every year the flu kills far more people! By getting my shot, I’m doing two things: teaching my immune system how to fight off the influenza virus likely to be common this season, and also keeping me from becoming an unwitting host to the virus, able to infect others.
That’s critical. For me personally, if I get the flu the odds are I’ll be miserable for a few days and more whiny than usual. But my wife is immunocompromised, and if she gets a full-blown infection, the complications could be very serious. That’s why we get our immunizations every year. It helps build herd immunity, and that protects people who cannot get the shot and could get critically ill from the flu.
Sure, Ebola is scary, but it’s made far scarier by the media in this country that have their priorities grossly out of whack. Given how communicable influenza is, and how dangerous it is, they’re spending way too much telling you about the wrong virus.
And that’s not even including measles, pertussis, and more diseases that are making strong comebacks due largely to the anti-vaccination movement. But I’ve already been pretty clear how I feel about that.
Go talk to your board-certified provider and find out what’s best for you. And if they recommend it, go get yourself vaccinated.
And before you ask about the T-shirt I was wearing ... did you see yesterday's post?
Self-Portrait 10 Miles From a Comet
Holy Periodic Comet Photos! Check. This. Out!
That is a self-portrait taken by the Philae landing craft onboard the Rosetta space probe, when they were just 16 kilometers (10 miles) from the comet 67P/Churyumov–Gerasimenko. You can see the side of Rosetta on the left and the solar panel that’s keeping it powered on the right.
And at the top is the comet itself, magnificent and moody in this high-contrast grayscale composite (two images were combined so that both the spacecraft and comet were exposed well). You can even see a jet emanating from the comet, a stream of gas blown out as ice is hit and warmed by sunlight. Stunning.
Rosetta is nosing closer to the comet, and will release the Philae lander in a few weeks. On Nov. 12, the probe will touch down on the surface of the comet, a milestone in our exploration of space. Judging from the quality of this picture, what we will see on that day will be jaw-dropping.