Astronomy Picture of the Day . ... Credit Copyright: Marat Ahmetvaleev Explanation: A meteoroid fell to Earth on February 15, streaking some 20 to 30 kilometers above the city of Chelyabinsk , Russia at 9:20am local time. ... An estimated 500 kilotons of energy was released by the explosion of the 17 meter wide space rock with a mass of 7,000 to 10,000 tons. ... 2011 2012 . ... NASA Web Site Statements, Warnings, and Disclaimers . ... Publications with keywords: bolid - meteorit - meteoroid . ...