Today, two cosmic visitors made the news around the globe today, February 15, 2013. First, this morning an unexpected visitor blazed through the mid-morning sky of Russia near the city of Chelyabinsk. It produced a spectacular fireball accompanied by a shockwave that resulted in a sonic boom. The shockwave made windows shatter which resulted in injuries to hundreds of people. It is very unusual that meteorite falls cause injuries. To date there is no documented case of a human casualty caused by a meteorite although some injuries have been reported from previous falls. Officials recovered several meteorite fragments today, which demonstrates that the meteor was not caused by a piece of space junk. They also located a fresh crater about 20 feet in diameter. Seven government airplanes were sent to look for more fragments that survived the entry.
The first estimate was that the rock was about 22,000 pounds before it hit Earth’s atmosphere, which would translate into a diameter of almost 6 feet if the rock had a typical density of a meteorite. These numbers will most likely change significantly after better estimates and after the first petrological and chemical analyses are available. A meteorite fall of this size could happen every few years statistically speaking. The rare thing with this event is that it happened over an inhabited area during the late morning commute, so many people witnessed it. This event is most probably not related to the much larger 150-feet asteroid 2012 DA14, which will miss Earth later today by only about 17,000 miles. The flyby of asteroid 2012 DA14 was expected will be the closest observed approach of an object of that size.
Fireballs like the one observed in Russia today are spectacular displays of nature. It an interesting to realize that each of the 45,000 meteorites in the world's collections entered Earth atmosphere as a dazzling fireball! Once landed fragments need to be carefully stored and curated in a collection facility, so that they can be made available for scientific studies that will help to improve our understanding of nature and our origins.