Rare meteorite that exploded in US was fastest to hit Earth


A meteorite that exploded as a fireball over the US earlier this year was among the fastest and rarest meteorites to have hit the Earth, travelling a highly eccentric route to reach our planet.

Researchers led by UC Davis, SETI Institute and NASA found that the meteorite - a carbonaceous chondrite - that fell over California's Sierra foothills on April 22 was the rarest type known to have hit the Earth.

It is composed of cosmic dust and presolar materials that helped form the planets of the solar system.

Scientists learned that the meteorite formed about 4.5 billion years ago and was knocked off its parent body, which may have been an asteroid or a Jupiter-family comet, roughly 50,000 years ago.

As it flew toward Earth, it travelled an eccentric course through the solar system, flying from an orbit close to Jupiter toward the Sun, passing by Mercury and Venus, and then flying out to hit Earth.

The high-speed, minivan-sized meteorite entered the atmosphere at about 102998 km per hour. The study said it was the fastest, "most energetic" reported meteorite that's fallen since 2008, when an asteroid fell over Sudan.

"If this were a much bigger object, it could have been a disaster. This is a happy story in this case," said researcher Qing-zhu Yin in a statement.

Before entering Earth's atmosphere, the meteorite is estimated to have weighed roughly 45359.2 kg. Most of that mass burned away when the meteorite exploded.

Meteorites like Sutter's Mill are thought to have delivered oceans of water to the Earth early in its history.

Using neutron-computed tomography, researchers helped identify where hydrogen, and therefore water-rich fragments, resides in the meteorite without breaking it open.

For the first time, the Doppler weather radar network helped track the falling carbonaceous chondrite meteorite pieces, aiding scientists in the quick recovery of them, the study reports. Yin expects that the weather radar data in the public domain could greatly enhance and benefit future meteorite recoveries on land.

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