The World Didn’t End

Asteroid Flys By, Earth is Still Here

This image of Asteroid 2011 MD was shot by Marco Langbroek five hours before the closest approach, using a "remote" telescope, the 0.61-meter F/10 Cassegrain of Sierra Stars Observatory (G68) in California. The CCD image is a 30-second exposure. The fast moving asteroid has tracked a clear bright trail on the image during these 30 seconds. Field center is approximately RA 15h35m57s, dec. +19.441 degrees. Image from 08:32:00 to 08:32:30 UTC (June 27th 2011).

While you were doing your daily thing a little while ago, a little chunk of rock flew by our planet at a distance of 12,000 kilometers (7,500 miles).  It was Asteroid 2011 MD, an Earth-grazing object that is about ten meters (about 30 feet) wide and tumbling through space on its way over our atmosphere and through our flock of artificial satellites.

As NASA scientists predicted, the rock didn’t pose any danger to the planet. But, this is yet another reminder that we live in a solar system populated with stuff that also orbits the Sun, stuff that we don’t always see until the last minute. And, every so often, we do spot something that comes uncomfortably close to our planet. This is perfectly normal in solar system asteroid populations and their orbital dynamics, and is usually nothing to worry about. Until it is.

So far, we’ve been lucky, but let’s put this into perspective. The last really huge bash into our planet made life miserable for the dinosaurs some 65 million years ago, but it wasn’t made by a ten-meter-wide rock. That object was more like 10 kilometers (16 miles) across. Meteor Crater in Arizona was dug out by something about 50 meters (about 150 feet) across, and that impact probably made life miserable for whatever animals (woolly mammoths, maybe) that happened to be ranging around that formerly grassy and temperate plain on that fateful day some 50,000 years ago.

A lot has been made about the fact that we need some sort of “asteroid early warning system” to keep us apprised of such close flybys. We seem to have one now, since this one was discovered on June 22, 2011. But, I think what the community really wants is better detectors to find these things earlier. The little rocks,which are harder to spot, aren’t quite so much a danger as the big rocks — which we should be able to spot sooner than a few days before they get close enough.

What should we do with that information? Just what we do now. We note the approach, the speed at which the object is traveling, and its size and rotation rate, and astronomers around the world (both amateur and professional) arrange to get images of the thing. In fact, for this one, images and movies are already starting to stream in to places like Spaceweather.com. More will show up as astronomers track its passage.

What if a newly discovered rock is bigger than these little guys, and headed straight for us? Well, that’s the scenario that worries scientists and makes the press salivate and write about each asteroid as if it were “the” one. Such a press frenzy for every little rock chunk  is not scientific, but it does sell click-throughs and page views. Believe me, if the big one were on the way, it’d be hard to keep scientists quiet about it, and I can just imagine the über-frenzy the press would lapse into.

Not only would scientists want to study it all the way in (I mean, come on — the opportunity to study an asteroid both visually and spectroscopically as it plunges through our atmosphere is at once an interesting scientific study and a sociological phenomenon), but every politico, evangelist, and wannabe commentator would have their own take on what it “means”. I don’t know about you, but I’d far rather see rational scientific discussion rather than uninformed ranting… but perhaps I’m damning the pundits unfairly ahead of time.

Nah.

In the meantime, we should embrace the science that’s being done on the little guys that rush past. Each one tells us a bit more about our near-Earth orbital environment, and sometimes we even learn more about the kinds of debris chunks that flash past in the night.