Earlier today, (Monday, June 27 2011) at 17:01 UTC (1:01 PM Eastern US time) a small rock, roughly 10 meters in size, and named Asteroid 2011 MD, flew right past the Earth. In fact, if flew really really close to Earth, at about 12,400 km (7430 mi) from Earth’s surface. That distance is less than the diameter of the Earth itself! Or about 1/32 the distance to the Moon. But astronomers were dead on in determining that it would miss us.
|Trajectory of near-Earth asteroid 2011 MD passing Earth on June 27, 2011. Credit: NASA/JPL Near-Earth Object Program Office.|
It is actually fairly easy to determine where things are heading in space, or at least in the vicinity of our Solar System. The advent of Kepler's laws of planetary motion, along with Newtonian physics and some other neat tricks of the trade, and super computers for crunching the numbers, and really all that is needed is a velocity and a direction. So astronomers generally have a high degree of accuracy on object motion, there are perturbations every once in awhile, but this is usually because of some unseen gravitation interaction.
The biggest threat when it comes with asteroids of this size is the lack of warning. 2011 MD was discovered a mere 5 days before our encounter with it. Now, some people have been claiming that if an asteroid like this were to impact the Earth, it would send a tsunami across the planet twice. Which really just is not true. This was a loose, stony asteroid, like most asteroids, and would have broken up harmlessly in the atmosphere with no ground damage. If anything, it would be a hell of an early fireworks show. The worrisome ones are made up of iron, but aren't very common.
|2011 MD on Monday, June 27, 2011 at 09:30 UTC. Credit: Ernesto Guido, Nick Howes and Giovanni Sostero at the Faulkes Telescope South|
Of course, it was also a great chance for amateur and professional astronomers to study an asteroid up close. Lately, it's been up to us to send probes and robots to check out asteroids, so it's nice for them to stop by for a visit once in awhile. There have been some great photos posted in this Universe Today article, and Spaceweather.com has a couple of images and movies up. Researchers have also used radio telescopes to study this piece of Solar System history.
Over at Bad Astronomy, Phil Plait wrote an excellent article and suggested that this is the kind of object that future space missions will be looking to explore. It would be relatively easy, easier than getting to the Moon, to put a man on an asteroid like this. Again, the biggest short fall being the lack of warning. But now that we know about this object, and know it will be about another 13 years before it comes this close again, maybe we can have a mission put together by then. Here's hoping to that great future.