Chelyabinsk Asteroid and Meteorite

October 28, 2013

Milacheylabinskmeteorite

Photographer: Mila Zinkova; Mila's Web site
Summary Author: Mila Zinkova

October 2013 Viewer's Choice On February 15, 2013, Yulia Karbysheva was teaching her class at a primary school in Chelyabinsk, Russia, when there was an extremely bright explosion in the morning sky. It occurred at 9:20 a.m. local time and was brighter than the morning Sun. She ordered her students to duck under their desks. A minute passed, then two. The children wanted to look out the windows, but Ms. Karbysheva wisely instructed them to keep covered; and then it came - an enormous shock wave blew out the school’s windows. Thanks to the actions of Ms. Karbysheva, there were no major injuries to any of her students. However, others weren’t as lucky. There were at least 1,500 people injured by the blast in Chelyabinsk.

So what actually exploded in the Chelyabinsk's sky? In mid February of this year, many astronomers were excited about asteroid 2012 DA14, predicted to pass closer to the Earth than even many man-made satellites.Chondriteinclusion However, scientists now know that the object that exploded over Chelyabinsk was a small asteroid that wasn’t in any way connected to 2012 DA14. Coincidentally, it traveled along its own orbit independent of 2012 DA14 but was missed by astronomers because it was hidden by the glare from the Sun. The Chelyabinsk asteroid belonged to the Apollo asteroids group, near-Earth asteroids having orbits that cross the orbit of the Earth. Actually, Earth crashed into this tiny asteroid -- it seems as though it crossed right in front of us. Thanks to many Russians’ “obsession” with dash cameras the Chelyabinsk asteroid event has became the best documented Earth/asteroid collision ever recorded.

A small piece of the Chelyabinsk asteroid (meteorite) is shown at top. It weighs  approximately 0.3 oz (7.7 grams) and is about 2 in (5 cm) across. A blowup of a portion of this bear-faced meteorite is shown at left. It has a rather unusual feature -- the yellowish inclusion. According to Dr. Alan Rubin, the inclusion is likely a large chondrule exposed at the meteorite’s surface. The red lines may be due to a fusion crust that penetrated the chondrule. Alternatively, they could be fractures in the chondrule that were quickly altered or oxidized, producing minor amounts of hematite.