CNN recently posted a story about how the Feb. 15 asteroid/meteor event was very, very unlikely: a 1 in 100,000,000 coincidence. I disagreed. I was all ready to blog about how CNN, yet again, got a non-scientist to write about science…and my indignation was already half out of the bottle.
Then I saw who wrote the article: Meg Urry, a highly respected Yale astrophysicist.
So, I sat on my hands for a second and re-evaluated the article. It does not contain any errors as far as I can tell. But I still contend that the article is misleading: saying that the asteroid/meteor event was a 1 in 100,000,000 coincidence is the wrong way to look at it.
I agree that if you multiply 1 in 3,650 days times 1 in 36,500 days you get something close to 1 in 100,000,000. But all you’ve proven is that for any given random day, there is only a 1 in 100,000,000 chance of such a coincidence occurring.
However, we now live in a post-Nate Silver, post Bayesian controversy world, right? We’ve known about asteroid DA14 for exactly a year (as of today). So the right question to ask, before it flew by last week, was: what is the chance that a human-injuring meteor will fly by on the same day? Well, given that an asteroid will already pass that day, the chance of a once-in-a-decade meteor flying by that same day is just 1 in 3,650 (that is, once in a decade).
I have the utmost respect for Dr. Urry. I suspect that the hyperbole-filled title of her CNN post was written by a CNN webmaster, not her. I still agree that the coincidence was unlikely, but given that DA14 was already expected to fly by, the Chelyabinsk meteor hitting on the same day does not sink into the realm of unbelievability.
[Trivia note: Chelyabinsk is the birthplace of Evgeny Sveshnikov, the chess grandmaster for whom the Sveshnikov variation of the Sicilian defense is named. And I do know that, as much as I like the Sveshnikov defense, I tend to go down in flames like a meteor whenever I play it.]