<< Update about Russia asteroid airburst>>
A surprise happened over the skies of Chelyabinsk in Russia today (Feb 15th), where a stony meteor/asteroid exploded in the air producing a shock wave that shattered windows for miles around. Videos from various sites near Chelyabinsk are gathered together at http://say26.com/meteorite-in-russia-all-videos-in-one-place . The airburst explosion was equivalent to about 300 kilotons of TNT, though it may have been as large as 500 kilotons of TNT. The Russia asteroid was not related to the main event of today: asteroid 2012 DA14. The Russia asteroid was probably about one-third the size of DA14 and it was definitely traveling in a different direction and speed than DA14. The Russia asteroid originated in the asteroid belt between Mars and Jupiter while DA14 is a "Near Earth Object" with an orbit around the Sun that is similar to the Earth's.
[I use the definition of "asteroid" used by Don Yeomans of the NEO program, that asteroids are small, inactive, (usually) rocky bodies orbiting the Sun a meter or larger in size, while a meteoroid is less than a meter in size, therefore the "Russia meteor" is really a "Russia asteroid".]
Infographic of the Russia asteroid airburst from The Telegraph (UK). Select the image to view a larger version.
Want to find out what we are doing to make sure we don't get surprised again? See the B612 Foundation for more.
<< end of update about Russia asteroid airburst>>
The 150-foot diameter asteroid 2012 DA14 will pass to within just 17,150 miles of the Earth at 11:25 AM Pacific Time on February 15th. It will move from south to north so people in the northern hemisphere won't be able to see it until just before close approach. Although it passes closer than the ring of geosynchronous satellites that orbit the Earth, DA14's trajectory is such that it passes through the ring going from south to north without hitting anything. Something like DA14 passes near the Earth every 40 years on average and an impact happens roughly once every 1200 years. DA14 has no chance of hitting Earth for at least the next century. Something like DA14 hit the plains of northern Arizona about 50,000 years ago to make the kilometer-wide crater now called "Meteor Crater". However, the Meteor Crater asteroid was made of iron, so it packed even more of a punch than would a typical asteroid like DA14 that is made primarily of stone. More recently, something the size of DA14 is thought to have created the airburst over Tunguska, Sibera that leveled hundreds of square miles of forest in 1908. An impact of something as small as DA14 would be equivalent to 2.4 megatons of TNT---enough to wipe out a city the size of Bakersfield but not have a global effect. Something a kilometer or more in size hitting the Earth would have a global effect, threatening the survival of our civilization.
Here are the things I do to fact-check any media news item of a possible asteroid/comet impact. I check out the news headlines on NASA's Near Earth Object Program website at http://neo.jpl.nasa.gov and the IAU's Minor Planet Center at www.minorplanetcenter.net. I will also look at Sky and Telescope's news section at www.skyandtelescope.com for something that hasn't been reported yet in the weekly news email they send out. Take a look at the NEO and MPC websites when evaluating any scary story of an upcoming collision. There are a lot of "junk science" websites and TV shows out there, most designed to capture your attention by scaring you in order to sell the products advertised on the website or show. To find out more about the effects of an impact on Earth, see the Earth Impacts webpage on my Astronomy Notes site at www.astronomynotes.com .
last updated: February 15, 2013
Webpage contact: Nick Strobel