I am extremely honored and pleased to announce that my talk, "An asteroid impact can ruin your whole day", is now featured on the TED website!
I gave this talk in September at TEDxBoulder, and I had a fantastic time. The talks were great, and it was wonderful to be a part of that.
However, I made two errors in this talk. One was logistical; I forgot to say that the "dinosaur space program" line is from science fiction writer Larry Niven, and for that I apologize to him — I usually do credit him, so I’m not sure what happened there.
The second error?
I’ll be giving my "Death from the Skies!" twice in Texas next week:
1) First, I’ll be speaking at Rice University in Houston on November 14th at 4:00 p.m. in Herzstein Hall’s amphitheater, then
2) I’ll be at the University of Texas – Pan American on November 15th for a 7:00 p.m. talk at the Student Union Theater. The UTPA event requires registration, so sign up! [Update: another page about the UTPA talk is here.]
The talk is about asteroid and comet impacts, and how one could ruin your whole day. I know there are BABloggees in Texas — you guys come out of the wordwork when I write about The Lone Star State — so come on by!
The eyes of many astronomers — and the eyes of their telescopes — were aimed at the asteroid 2005 YU55 a few days ago, when it passed the Earth at the relatively close distance of about 320,000 km. One of those eyes was actually in space as well: NASA’s Swift satellite. This spacecraft was designed to look at the sky in the ultraviolet, X-ray, and gamma rays, all high-energy forms of light emitted by the most violent events in the universe: exploding stars and gamma-ray bursts.
But the Sun emits UV, and rock can reflect this light, too. So Swift observed YU55 as it passed us, and got this very interesting footage of it, what I think is the coolest I’ve seen so far:
[You can also watch it on YouTube if you prefer.]
Pretty neat, and by looking at the rock at different wavelengths, we can learn about its structure and composition, too.
But I know what you’re thinking: in the video, why did YU55 curve around as it moved? As it turns out, I was expecting this when I watched the video! What’s going on*?
The asteroid is in elliptical orbit around the Sun, but over the short period of time covered by this video — about 20 minutes — it’s essentially moving in a straight line. The reason the path is all bendy is because Swift itself is in motion! Swift orbits the Earth, circling us once every 90 minutes or so. As it moves around us, its viewpoint is changing, and that motion is reflected in the asteroid.
Tomorrow, November 8, the 400-meter-wide asteroid 2005 YU55 will glide past the Earth, missing us by a very comfortable margin of 320,000 kilometers (200,000 miles). This distance is three-quarters of the way to the Moon, and is in fact so far that you’ll need a decent telescope to see it at all.
However, I’m starting to see rumors that the asteroid will have an effect on us. I expected this — it happens every time there’s a decent-sized rock that whizzes past us. That’s why I wrote a post about it a few months back, but I want to follow up on it. Why? I’m getting wind of some folks worried about YU55, including a couple of notes on Twitter saying there are people blaming Saturday’s earthquake in Oklahoma on YU55!
Let me be clear: no asteroid, YU55 or otherwise, can cause earthquakes as they pass. Even Ceres, the largest asteroid in the solar system, would have to practically skim the top of our atmosphere to have any real effect on us. YU55 is dinky, and will miss us by 25 times the diameter of the Earth!
And c’mon: why would it shake up Oklahoma? Japan, Turkey, Chile, California — there are dozens of seismically active spots on Earth that are more prone to earthquakes. Someone claiming an asteroid causing one in Oklahoma should set off alarm bells in your head*.
I’m sure there will be other claims as well. People will squeeze whatever they can out of this event. I saw it happen in 2008 when a similarly-sized rock, 2007 TU24, passed by us at a distance of more than half a million kilometers. Things got so ridiculous with the doomsday scaremongering back then that I made a video to alleviate fears. I’ve embedded it here; all you need to do is replace "2007 TU24" with "2005 YU55", and the 530,000 km miss by 320,000 kilometers, and all the stuff I said back then still applies.
And for those of you still prone to worry, let me add this: I was right. And when was the last time an end-of-the-world doom crier was right?
Let me give you a hint: Never.
Not that this will stop them. There’re two things I know for sure: they’ll never admit they were wrong, and there will always be something else. The next asteroid, the next full Moon, the next star they think will explode, a pole shift, whatever.
As long as people aren’t familiar with the reality of the situation, there will be fearmongers to take advantage of the situation. That’s a big reason I do what I do, and why I have to do what I do.
Image credit: NASA/Cornell/Arecibo
* You’d think at least they’d claim it was last week’s solar flare that did it; after all, it’s Oklahoma, where the solar wind comes sweepin’ down the plain…
On November 8, an asteroid 400 meters across will pass by the Earth, missing us by the very comfortable margin of about 320,000 kilometers (200,000 miles). Named 2005 YU55, it’s been known for some time that this pass will occur, and astronomers are jumping on the chance to observe it.
First off, it’s no danger to Earth right now. It’s what’s called a Potentially Hazardous Asteroid because its orbit intersects ours, but observations have shown it won’t be a danger to Earth for at least a century, and probably much more. There’s been some scare-mongering about it over the past few months, but as usual that’s all baloney. This rock will pass us safely, sailing on into the night.
But given that this is close in astronomical terms, astronomers will be observing it carefully. There are plans to use NASA’s Deep Space Network of radio telescopes, as well as the Arecibo ‘scope in Puerto Rico (which was used to make the image above back in April 2010). They’ll be able to see features on this rock as small as two meters across, which means we’ll actually get some interesting images of it, I hope. I’ll post those as soon as I see ‘em (which will be after November 8).
It’ll only get to a magnitude of about 11 — only 1/100th as bright as the faintest star you can see with your unaided eye — so you’ll need a decent-sized (12.5 cm at least) telescope to see it. 320,000 km is 3/4 of the way to the Moon, and this asteroid is small and very dark. Observing it will be tough, but you can get more info on how to do it at the Minor Planet site and on The Minor Planet Bulletin (PDF).
When I was a kid, asteroids were not much more than mysterious points of light, but now we have the technology to see them in detail from the ground, and even send space probes to get good, close looks at them! And, of course, the technology to spread those images and information as quickly as the speed of light around the globe. Sometimes that’s used to spread misinformation, but it also can be used to show people what a cool place we live in. I prefer the latter.
In September 2011, I was honored to be on the speaker roster for TEDxBoulder, which is a local though independently-run version of the much-lauded TED talks. My talk was about saving the Earth from asteroid impacts, something I’ve spent a lot of time thinking and writing about.
The talk is online, and I’ve included it here:
The "We have a space program" line is from science fiction author Larry Niven, so I can’t take credit for it, though I modified it to add the "we can vote" bit. Also, this was the biggest audience I’ve ever spoken to, and it was a great crowd. I was almost last on the roster, but the audience was attentive and clearly enjoying themselves. It was a really fun, energizing, and mind-expanding evening.
The other talks that night are being put online as well. If you ever get a chance to attend a local TEDx conference, you should.
I’ve been scratching my head for a long time, trying to figure out why NASA hasn’t been taking the idea of preventing asteroid impacts more seriously. This idea has everything you’d want in a project: it’s cool (I mean, c’mon, we’re talking asteroid impacts!), it’s doable, it’s not terribly expensive, it’s already on the public’s mind thanks to Hollywood, and there’s always the eensy-weensy possibility that you might save all of humanity.
Yet, despite this, it’s been an uphill battle to get NASA to pay attention. While the space agency has been very good about supporting early detection programs, the support for a space mission to prevent an impact has been lacking. Of course, given their relatively small budget (<1% of the federal spending) I imagine taking on anything like this would be difficult.
So I’m pretty chuffed that the European Space Agency is looking into saving our collective skins. They’ve being studying the feasibility of a mission to test methods of asteroid impact mitigation, including a very very cool space mission they’ve dubbed Don Quijote (first proposed in 2002, and may launch sometime after 2020). It’s actually two separate spacecraft: one to impact a small near-Earth asteroid, and another to monitor the event carefully to see what happens, including how much the orbit of the asteroid was changed.
The idea here isn’t complicated: if we see an asteroid on an impact trajectory with Earth, we want to change the orbit so it doesn’t hit us. We could try blowing it up, but that’s actually a bad idea: at best it creates a lot of debris that can still smack into us, some of which may still be big enough to do us serious harm. So a better idea is to make sure it doesn’t hit us at all.
The Dawn spacecraft entered orbit around the main belt asteroid Vesta just a few weeks ago, and images are coming back in dribs and drabs. NASA just released this fantastic one, taken by Dawn’s wide-angle camera:
[Click to protoplanetate.]
Pretty cool, eh? Vesta is about 500 km (300 miles) across, so you’re seeing about half the rock from top to bottom here. The most obvious thing are the two ginormous craters. Note the scale bar; the bottom crater is about 70 km across, and the top one about 50. The fact that they nearly overlap, and are clearly the two biggest features for a big area around them, makes me think it was a double impact. Many asteroids are binary, so two objects a few kilometers in size and orbiting each other 50 or more kilometers apart would do the trick*. [Update: Emily Lakdawalla agrees.]
The bottom crater is weird; the bottom right edge looks like it’s collapsed a bit, marring the near perfect circle of the rim. That feature itself looks like an arc of a circle; might there have been a third rock that hit? That seems unlikely, and I have a hard time believing even a piece of the rim of a previously existing crater would’ve survived the impact!
Also, look around the two craters. See how far away from them, the surface is saturated with smaller impact craters? Near the big two, though, there are fewer. It’s a sure bet the impacts threw out a lot of debris which blanketed the area. The escape velocity of Vesta is a meager 350 meters/sec (about 750 mph); a lot of the stuff blown out on impact would’ve been moving faster than that! So some would’ve escaped the asteroid entirely, but some would’ve settled down over hundreds of square kilometers of area around the site.
Both crater floors have a filled-in appearance. No doubt a lot of energy of the impact went into melting the surface, which flowed inward. Some of that might be slumped material from the crater edges, too. My knowledge of how craters form is limited, especially on asteroids. But I’d love to see high-resolution images of this! That would answer a lot of these questions straight away.
And of course, we’ll be seeing those soon. Dawn is slowly moving down toward Vesta, gradually lowering its height until it settles into its final orbit. At that point, we’ll be getting really high-res shots, and maybe a few enigmas will be solved… only to be replaced, no doubt, by ten times as many. Fun!
[Edited to add: there is that biggish third crater at the top, of course, but I’m not sure it’s related to the other two. It’s much smaller, for one thing, and there are several other craters that size nearby that appear unrelated. It has a softer rim, implying greater age due to erosion (meteorite impacts), and isn’t aligned with them — though the sharp curvature of the asteroid makes that difficult to verify; in some images they look more colinear (that is, aligned).]
Image credit: Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
* At first the size of the impactors was a guess, but then I poked around and found this crater diameter calculator. I put in values for Vesta, and found that the impactors would’ve been roughly 5 km across. My instincts, sometimes, are good.
NASA’s Dawn mission team just revealed the first full-frame image of the giant main-belt asteroid Vesta, and it’s really, really cool:
Yegads! [Click to asteroidenate.]
Vesta is about 500 km (300 miles) across, but is clearly non-spherical, so take that as an average. That’s roughly the size of Colorado! So it’s a big rock, and we’re now seeing it in exquisite detail. This image was taken on July 24, from a distance of about 5000 km (3000 miles).
Man, there’s nothing like being there.
There’s a lot to see. The surface of Vesta is varied, with craters of various sizes (as expected) and depths. I’m very curious to see that there are some darker spots (like in this image) that look like material dredged up from under the surface from impacts; we see this on the Moon and other bodies as well. Some preliminary mineralogical maps show varied distributions of minerals on the surface as well.
An animation of Vesta rotating has also been put together, and really shows how odd this little world is:
[Make sure to set the resolution to at least 720p!]
Look at how the surface changes: you can see smoother regions, cratered regions, places that are darker, some where it’s brighter. Clearly Vesta has been battered over time — the entire south pole region is an impact basin, and those parallel grooves are from waves of energy moving through the asteroid during the impact event — and hopefully its history will be unraveled when higher-resolution images come in.
In fact, the scientists at the press conference talked at length about how these first images have raised a lot of questions, and stressed several times how more images will reveal the answers. Dawn will orbit Vesta for a full (Earth) year, so we should get plenty of data that will keep folks busy for a long time.
… and it won’t end there. After Dawn leaves Vesta it’ll head over the Ceres, the largest of the main belt asteroids. I wonder what it’ll find there? But it’s too soon to worry about that! We have a whole new world to explore for now.
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
NASA’s Wide-field Infrared Survey Explorer (WISE) has found the very first asteroid that (more or less) shares an orbit with Earth! Called 2010 TK7, this asteroid is about 300 meters (roughly 1000 feet) across, and is the first in an up-to-now theoretical class of objects called Earth Trojans.
Here’s a WISE image of the little bugger:
Doesn’t look like much, does it? Of course, from 80 million km (50 million miles) from Earth it’s amazing we can see it at all. Moreover, given its position in the sky, it’s only up during the day as seen from Earth; it was only discovered because WISE orbits the Earth, so the sky is always dark. Also, WISE sees in the infrared, so warmer objects are easier to spot. This rock is probably around the freezing point of water or so, which, to an astronomer, is pretty warm.
So what makes this asteroid special?