Asteroid headed for Earth….sort of. November 7, 2011

No doubt everyone can breathe a sigh of relief after reading those last two words of the headline.  But it is true, sort of.  An asteroid that is a quarter of a mile long — bigger than even America’s largest aircraft carrier, is headed towards the near-vicinity of Earth.  Officially named YU55, its current trajectory has it flying by the third rock from the Sun on Nov. 8 at a distance of only 202,ooo miles — closer than the Moon (at only 240,000 miles away).

Scientists have been studying this asteroid long enough to be as certain as humanly possible that it will not hit Earth.  If it did — Heaven forbid —  though, the result would be a possible oceanic impact, with 70-foot tsunami waves 60 miles away, and causing a 7.0 earthquake that that part of the world.  So says asteroid impact expert Jay Melosh of Purdue University, my alma mater.

This scenario pales in comparison to the fictional scenario from Armageddon, where that fictional asteroid was the size of Texas, and should it have crashed into the Pacific Ocean, would have caused a tidal wave to wash up to Denver, and enough dust to cloud out the Sun for an epoch.  But as Melosh points out, impacts of the relative proportion of the very real YU55 happen about every 100,000 years.  The comforting, silver lining in that otherwise rather disturbing thought is that such impacts are survivable, provided that you’re not within, say, 75 to 100 miles of said impact.

In the meantime, though, this close encounter with the asteroid kind gives scientists and lay astronomers alike the golden opportunity to see a huge chunk of extraterrestrial rock up close and personally.  Sites for astronomy enthusiasts have been mapping where in the sky YU55 is expected to pass through.  But more importantly, a prevailing theory regarding how the Earth took form involves asteroids, specifically that they were responsible for depositing water and minerals on the planet as it was cooling some two or three billion years ago.  YU55’s close, though fleeting, proximity will give professional researchers the opportunity to collect telemetric data that will allow for scientists to test this theory.  It also lets astronomers take a close look at the class “C” of asteroids, which are very common but not very well understood.  No doubt the upcoming astronomical event could help us rectify that problem.