Blogs / Bad Astronomy

Regular readers know that Saturday Morning Breakfast Cereal is one of my favorite web comics. This morning, he had an astronomy-themed bit of snark:

I’ve blocked out the woman’s reply, so you’ll have to click through to see the punch line.

And I love Zach, the artist, I really do, but…

SPOILER for the joke:

Meteorites are after they hit the ground. Meteors are when they are still in the air and glowing, and the solid part is called a meteoroid. There is no semantic definition of when a meteoroid is is big enough to be called an asteroid, but given the size depicted in the cartoon, I’d say that one counts.

See? This is why you shouldn’t date an astronomer. Unless you like that sort of thing. Oh baby! Talk cosmic to me!

Tip o’ the Whipple Shield to Brian Carroll who tweeted the link to Rebecca at Skepchick, who is in turn technically correct in her title since I’m married and Mrs. BA can kick anyone else’s asteroid herself.

What we would do without Twitter? If not for that 140 character service, I never would have found out that Dr. Chaotica wrote and performed a song called "Death from the Skies!", based on what is considered by some (OK, just me) to be the finest book to come out in 2008 (and 2009 in paperback).

I’m more of an ABBA and Shostakovich guy, but I have to admit I found my toe tapping to this happy tune of death and destruction from space.

I am just now hearing about an asteroid estimated to be about 10 meters across blowing up over Indonesia on October 8. Apparently no one was injured. I have no clue how I missed this, but The Telegraph has the story. This is not an everyday occurrence, but 10 meter rocks probably do come in and explode high over the Earth’s surface every few years or so. If they’re rock they won’t make it to the ground; instead they blow up due to the incredible force of their passage through the air (in this case, the explosive yield was about 50 kilotons of TNT). Smaller rocks will rain down, though.

If it’s metal, that would be worse. It might withstand the aerodynamic pressure and hit intact. However, like I said, this is pretty rare.

The newspaper article above plays up the "What if it were just a bit bigger?" aspect, which is true enough, but what can we do? A rock or chunk of metal 30 or so meters across is dangerous, sure, but is too small to see very far out, so there’s not much we can do about it. That’s not exactly great news. It’s possible it might get spotted a day or two in advance — we’ve seen smaller ones with a day’s warning — but most likely our first warning would be the flash in the sky.

It would cost a fortune, hundreds of millions or more, to set up telescopes to scan the sky deeply and quickly enough to see all these rocks. There are some ’scopes like that in the works, but I suspect the political will to create the network needed just isn’t there. It may take a few more impacts like the one over Indonesia before people start taking this seriously.

Regular readers know I have an marginally unhealthy crush on Felicia Day. Of course, so do millions of other people, so she’s probably relatively safe from me.

But are we safe from… colliding galaxies? Apparently, only Felicia knows for sure, as she demonstrates in this NASA PSA:

Hey! That was funny! Like, really funny! Lots of inside jokes for Felicia’s fans, too ("Is this your first time doing an internet video, Miss Day?") A lot of times videos like this are just painful, but this one is actually really good. Felicia is great, and the Sean Astin stuff cracked me up.

And I think someone’s been reading my book… OK, probably not. But the way she talked about all the astronomy was very natural and smooth, so I just know deep in her heart Felicia’s harboring a strong and undeniable love for astronomer. I mean astronomy. Yes! Astronomy! Of course that’s what I meant!

Sigh. We’ll always have Comic Con.

Tip o’ the Guilded lily (see what I did there?) to Javier Pazos.

Regular readers know Brian Cox: he’s a physicist, a rock star, a TV science documentary host, a skeptic, and a friend. At TAM London I did a very brief interview with him. Since he works at the Large Hadron Collider in Geneva, I had something on my mind…

Now, how long do you think it’ll be before every crackpot doomcrier takes this video out of context, and/or seriously?

One thing I really dislike about conspiracy theorists — well, one of many, many things — is their lack of a sense of humor. Maybe the tin foil hat drains that part of your personality away.

They’re too late anyway.

Related links:
Video interview with Ariane Sherine
Video interview with George Hrab
Review of TAM London
The James Randi Educational Foundation/a>

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 .