Back in April of this year, a meteorite entered the atmosphere of Earth creating a bright fireball in the daytime sky on April 22 over Northern California. For scientist Peter Jenniskens, the meteorite impacted right near his base of operations meaning he only had to drive a few hours to search for fragments from the meteorite. The trajectory of the meteorite was well documented and was picked up by three Doppler radar stations on the ground.
According to the scientists, any time the entry trajectory is picked up by measuring equipment on the ground it makes it much easier to find fragments of the meteorite once it impacts the Earth. Jenniskens and other researchers were able to find 77 smaller pieces of the meteorite on the ground and the fragments totaled nearly a kilogram. 1 kg of meteorite fragments is a fairly significant find on the ground, but represents only a tiny fraction of the meteorite's original mass.
According to the scientists, the asteroid is believed to have had a mass of about 40,000 kg giving it a diameter of 2.5 to 4 m. The meteorite entered the Earth's atmosphere from the East and exploded at an altitude of 48 km above the Earth's surface. The explosion was massive, releasing energy equivalent to 4 kilotons of TNT.
According to the scientists, that is about one fourth of the yield of the nuclear weapon detonated over Hiroshima. The explosion was so large it was picked up by two infrasonic detector stations designed to monitor compliance with a ban on nuclear weapons testing. Scientists say that the meteorite entered the atmosphere at 28.6 km/s or about 64,000 mph. That entry speed is a record for the highest entry velocity recorded for recovered meteorites.
[via Scientific American]