I’m still kind of rattled and befuddled by the Chelyabinsk meteor. On Feb. 15, 2013, I had a story in the newspaper saying that, fear not, even though an asteroid was going to make a close pass by Earth that afternoon, you shouldn’t get too worked up about it because these rocks don’t hit Earth very often. The story all but said: Asteroid Won’t Hit Earth Today.
And then an asteroid hit the Earth. That day. That morning!
I think the asteroid hit the Earth right about the moment that the newspaper with my story saying Asteroid Won’t Hit Earth Today was flying from the hand of the delivery person onto the front walkways and front lawns of subscribers around town. Even as the known asteroid came in from one direction, another rock, unknown, emerged from the glare of the sun and plunged into the atmosphere over Russia, exploding and sending fragments across the landscape. So I guess I called that one wrong.
Here’s what we can’t do: Get hysterical every time a rock passes near the Earth. This is because there are bajillions of rocks out there. Some are very big. And some of the big ones pass within a few million miles of the Earth — fairly routinely. Space is big in three dimensions — four if you count time — and thus these rocks are unlikely, over short periods of time, to strike our planet. (Yes, I know, a tyrannosaur was making this very point to a Triceratops when the big rock hit Chicxulub.)
This week, I’m sorry to report, we had a moment of hysteria. I hate to be a journo-scold, AGAIN, but someone’s gotta say something about this. On Monday the Internet lit up with reports that a big rock was on a path to nearly strike the planet Monday night. This was not true. But it made for a grabby headline. As in:
An Asteroid Will Almost Hit the Earth Tonight (from Motherboard)
And this one, which is even more alarming, from the Daily Mail*:
[*Update: A reader corrects me. The Daily Mail piece refers to a different asteroid, which will approach in March -- not Monday's asteroid. From the article: "[T]hey say the probability of the asteroid hitting Earth is just 1 in 909,000 and the risk of impact is likely to decrease as they collect more information.”]
The British papers really went to town on this story. The Guardian ran a piece headlined “Asteroid 2000 EM26: ‘potentially hazardous’ space rock to fly close to Earth.” The story online has a frightening looking illustration of a glowing rock plunging toward the Earth.
What did happen Monday night is that a rock discovered in 2000,believed to be roughly 900 feet in diameter, passed by the Earth at a distance of at least 2.1 million miles. That’s nearly nine times the distance to the moon. Is that “uncomfortably” close? That’s a subjective call. I’d say: Not really. And it’s not really news, because rocks THAT size pass THAT close to the Earth multiple times a year — and have been for billions of years. There’s no TREND here, other than the trend we are generating by writing breathless articles saying we’re all about to die.
Universetoday writes: “Similar sized asteroids, including ones passing even closer to Earth, zip by every month.”
Don Yeomans, the head of the Near Earth Object tracking program at NASA’s Jet Propulsion Laboratory, spoke to the Los Angeles Times, and said a rock that size should pass that close about once every six months. As you go down in the size scale, toward smaller rocks, you have a commensurate rise in the frequency of these rocks “nearly hitting” the Earth.
So why was this one newsy? Because the news business is a quirky beast. Someone put out a press release a few days ago. It was from the folks at Slooh, a “community” telescope service that streams stuff on the Internet from telescopes around the world. The Slooh people described this rock, 2000 EM26, as a “Potentially Hazardous Asteroid.” (Well, except it wasn’t even on JPL’s list of potentially hazardous asteroids. You can call up the list at any time, and, although it can be hard to interpret, the gist of it is that we currently know of no rocks that are going to hit the Earth in the foreseeable future.)
Anyway, Slooh streamed the attempted observation of 2000 EM26 as it passed the Earth Monday night. But no one could see anything. There was just dark sky. It’ll probably turn up in subsequent observations. Because these things move really fast relatively to the Earth, and are small and dark, they can be hard to spot.
The failure to detect the asteroid that was supposedly hurtling toward Earth did little to calm the nerves of headline writers. The British newspaper The Independent ran a particularly deceptive article. The headline screams: “Asteroid 2000 EM26 ‘as big as three football fields’ hurtles past Earth.” With that is a stunning photograph of the Chelyabinsk fireball trail. The caption says: “Slooh Space Camera tracked the asteroid as it raced past at 27,000 mph.” (The comments on the article suggest that most readers understood that this was a Festival of Lies and that the image was from Chelyabinsk and not from Monday night.)
Reuters ran a story with the headline: “Earth marks close encounter with enormous asteroid”
Well, “close” is a squishy term. Antediluvian science writer that I am, I kind of want it to be closer than 2.1 million miles before I’m going to say this was even worth a paragraph. It’s conceivable that I’m a little jaded. Another day, another killer space rock. I dunno. I say move along, there’s nothing to see here.
[Update: This is a little bit technical, but I think some of you will appreciate the analysis of EM26, via email, from Alan Harris, a veteran asteroid expert:
The orbit of EM26 has a MOID [Minimum Orbit Intersection Distance] of 0.019 AU. That’s 2.85 million km, or 450 Earth radii. That number is extremely well determined, because that is very close to the part of the orbit it was in when discovered in 2000. So it simply can’t come closer. Depending on timing, it might pass considerably further away.This is the situation for almost all NEAs on discovery: we can immediately determine a MOID many times greater than the Earth’s radius and rule out a future collision in our lifetime, certainly long enough that the object will be re-detected and the orbit further improved all in due time without special attention. This is most emphatically the situation with EM26, and no special attention to this pass was warranted, nor is anyone “negligent” for not doing it. But, as has also become well discussed by now, but not before the Slooh affair, there is a large uncertainty in the position along the orbit. The reason is that an error in the period of the orbit will lead to an accumulating error in position along the orbit, while errors in inclination or eccentricity lead only to oscillating errors that are maximum about 90 degrees away from the point of discovery and brief tracking, but do not grow with successive orbits. So by now the position in orbit is uncertain by [plus or minus] a couple days, which translates to a couple million km, or about 350 Earth radii, even in terms of velocity relative to the Earth.]
Killer rocks are out there and we should try to detect them — and we have, in fact, been creating a catalog of the biggest ones, the civilization-busters. [Over at Slate, Phil Plait explains why we need to do more than we're doing.] But what we can’t do is lose our minds every time someone shouts that an asteroid is coming — because there are rocks all over the place and they’re part of Earth’s environment in space. We’re setting ourselves up for blood-pressure spikes if we overreact to every passing rock.
One of our challenges in the technological, scientific age is to sort through a long list of complicated risk factors. We have to figure out what’s worth worrying about, and what is exceedingly improbable. Here’s my hunch: The thing that’s going to get us, one day, isn’t going to be something on anyone’s radar.