Blogs / Bad Astronomy

Apophis is a 250-meter-wide rock with a special designation: it’s a near-Earth asteroid, meaning it passes close to our planet. In fact, in April of 2029 it will pass so close to the Earth — just under 30,000 kilometers (18,000 miles) — that it will actually get between us and some of our geosynchronous satellites!

Because it will come so close, the Earth’s gravity will change its orbit. There is a region of space called a keyhole (it’s actually kidney-bean shaped) and if Apophis passes through it like an arrow through a bulls-eye, the Earth’s gravity will change the asteroid’s orbit enough that in seven more years, in 2036, Apophis will hit the Earth! The odds of it passing through the keyhole are low; up until recently they’ve been quoted as 1 in 45,000. Not a huge concern, but worth keeping an eye on.

However, new observations have lowered these odds even more, to only 1 in 250,000. Pretty much at this point I’m not worried about this particular rock any more. The odds before weren’t great, but they’re so bad now it’s no big deal.

How does this work? The orbit of an asteroid is calculated using measurements of its position in the sky over time. There is a tiny uncertainty in those positions for many reasons: atmospheric distortion blurring the asteroid image being one of if not the biggest. The way to minimize that is to get lots of images so that the errors average out, but even then the orbit calculated has uncertainties. And the longer into the future you project the orbit, the worse it gets. In the case of Apophis, astronomer Dave Tholen used hundreds of new images of Apophis to refine the orbit and get the better statistics for its impact risk.

This happens quite frequently: a potentially dangerous asteroid gets better observations made of it, and the risk drops. In this case, that’s definitely a good thing. At 250 meters wide, an Apophis impact could do considerable damage to civilization. It wouldn’t be an extinction level event, but it would put serious hurt on humans. Still, it bears watching. I doubt the odds will go back up, but the more we pay attention to these things, the better!

Image credit: UH/IA.

No, this isn’t what you’re thinking. The comedy group LoadingReadyRun does a satirical newscast where the topic is, well, see for yourself.

I think someone’s been reading my book .

At Dragon*Con, I did a dramatic reading from my book, Death from the Skies! which was a lot of fun. I read from Chapter 1, about asteroid and comet impacts, and BABloggee Brandon Alexander recorded it.

After the actual reading I talked about impacts as well as other disasters I cover in the book — including my favorite, gamma-ray bursts. It was a lot of fun, and Brandon posted the video from it as well:

I know, I have a lot of fun wiping out the Earth. But it is fun to think about, as long as you remember the odds of any of these things happening are pretty low. Still. Yikes.

I love the cover of the paperback version of my book Death from the Skies!, but this guy loves it a lot. I knew the cover art was done by a talented guy, but didn’t realize just how wide a swath this guy cuts in the comic industry. That makes my book even cooler. You should buy one, and another for all of your friends. And a spare in case you accidentally drop one copy down a black hole or a gamma-ray burst vaporizes it.

On the last day of Dragon*Con — thus guaranteeing me to be tired, brain dead, unfocused, and generally zonked — I gave a dramatic reading from the first chapter of my book Death From the Skies!, which just came out in paperback and so I shilled it without mercy.

Unbeknownst to me, I was being taped. Normally I would object, but since they didn’t catch me scratching anywhere inappropriately, picking my nose, or cursing continuously, I’ll let you take a look.

Not bad considering what I had been out very late doing the night before. No, I won’t give details, but let’s say that an asteroid impact would’ve felt like a rally. This picture was taken during the jocularity if that gives you any clue.

My book, Death from the Skies!, is of course the best book you’ll ever read in any genre of all time. That goes without saying (at least, in my mind it does). So of course I want to see it selling as widely as possible…

But somehow, seeing a book about the ways the Universe can destroy the Earth coupled with a logo like this one, well, it’s more disturbing to me than maybe it should be.

My friend and fellow astronomer and astronomy evangelist Dan Durda just let me know he’ll be on tonight’s episode of Universe on The History Channel. He’ll be talking up what he does best: asteroid impacts and extinction events. Oddly, I have an affinity for those as well. So, if you have a TV check Dan out as he apocalypticizes. It’s on at 21:00 Eastern (US) time.