February 18, 2013. On Friday afternoon, NASA scientists reported that a space object was 15 meters in diameter and caused the explosion of a capacity of 300 kilotons of TNT. A little later, the energy yield of the explosion was increased up to 470 kilotons.
However, late on Friday NASA revised its estimates. The size of the meteorite has been increased to 17 meters in diameter, and the force of the explosion — up to 500 kilotons, the official report says department.
The meteorite was also significantly more massive than previously thought. Initially, his weight was estimated at 7,000 tons. But now scientists of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said that the meteorite weighed about 10,000 tons, and the time of the explosion had a speed of 64,373 km / h
"These new estimates were made on the basis of new data obtained with five additional infrasound stations located around the world. One of them is located in Alaska, more than 6,500 kilometers from Chelyabinsk, — explained the researchers. — Infrasonic station detected low-frequency sound waves that accompany explosion meteorites. "
Meteorite entered the Earth's atmosphere and exploded over the Chelyabinsk in 3:20:26 GMT on February 15. Evolved in the time of the explosion radiant energy eclipsed sun. Curiously, a rare astronomical event occurred several hours before the flight of a larger asteroid 2012 DA14 diameter of 45 meters.
Asteroid 2012 DA14 came within 27,000 miles of Earth on Friday, without presenting a threat to the planet. The span of the asteroid and meteorite explosion of Chelyabinsk is not linked, soobschet NASA since their trajectories have been quite different.
In addition, late on Friday another fireball was seen over San Francisco in California. This event — as a coincidence. Scientists call Chelyabinsk meteorite is extremely rare. Nothing like this in the sky over Russia happened since 1908, when exploded over Tunguska, a broader bolide.
"We believe that the events of this magnitude occur on average once every 100 years — said Paul Chodas, head of NASA's space program in the Middle. — If you have a fireball of this size, one can expect a large number of fragments, including quite large, which reached the surface of the Earth. "
Fragments of the meteorite were found in the Lake Tchebarkul
February 18, 2013. As reported by "RIA Novosti", scientists have studied the impact area of the meteorite on the lake Chebarkul in the Chelyabinsk region, discovered fragments of the celestial body. The specialists were collected 53 fragments of black solid of about 1 cm
Later, the samples were sent for analysis. Chemical analysis was carried out in the laboratory of the Urals Federal research and educational center "Nanotech". According to Victor Grochowski, a member of the Russian Academy of Sciences Committee on Meteorites, chemical analysis confirmed the extraterrestrial nature of the studied fragments. At this point in the study were identified: metallic iron (above 8%), olivine sulfite.
Later, for the registration of a new meteorite mezhdunardnogo catalog will be a more detailed study of the chemical composition. However, with the name of the cosmic body already decided. It will be called in honor of the lake, near which were found fragments — "Tchebarkul."
Meteor or meteorite
February 18, 2013. Meteor — This atmospheric phenomenon in the form of a smear due to a fall in the Earth's atmosphere meteoroid mass from a fraction of a gram to several tons. When entering the Earth's atmosphere at an altitude of 80-150 km from the friction surface of the meteoroid is heated, and they light up. The highest brightness of the meteors reach at an altitude of 50-60 km. They then vaporized and atomized. "Shooting Star"? a classic example of a meteor. When many meteors phenomenon called "Meteor Rain".
Meteorite — Is the most prominent meteoroid with the lowest initial rate of decline, reaching the surface of the planet. Meteorites are divided into iron, stone and iron-stone. Very rarely reach the Earth's large meteorites weighing hundreds of thousands of tons, the impact of which is accompanied by a powerful explosion (the Tunguska meteorite Sikhote-Alin meteorite).
Let us consider the main differences from the meteor meteorite:
1. Meteor — this light phenomenon in the atmosphere, the meteorite — a solid outer body.
2. Meteors are formed by tiny particles burning up in the atmosphere of the Earth. Meteorites reaches the Earth.
3. Meteors? frequent, rare meteorites fall.
In this case, a cross between a meteor and a meteorite. In astronomy, a phenomenon called fireballs.
The car? it is very large and a bright meteor, a long time preserving intact structure in the Earth's atmosphere and the flight is accompanied by a bright glow and the sound.
Especially large and very bright fireball called superbolides.
"It was a fireball — a large celestial body, in fact, a large meteor, which exploded when entering the lower, denser layers of the atmosphere, "- according to the website of the Russian Geographical Society. Something similar happened in the Chelyabinsk region in 1949, said Sergei Zakharov, head of the regional branch of the organization.
"The object is most likely a meteoroid or bolide"? commented Elena Gienko, assistant professor of astronomy and gravity of the Siberian State Academy of Geodesy. ? When approaching the Earth to split into two or three parts and exploded, causing a shock wave.