Space is a Graveyard of Planets: Most Deadly Meteorites Are Fragments of Six Ancient Worlds

Tuesday, 03 July 2018 - 1:00PM
Space
Astronomy
Tuesday, 03 July 2018 - 1:00PM
Space is a Graveyard of Planets: Most Deadly Meteorites Are Fragments of Six Ancient Worlds
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Image Credit: Outer Places composite from public domain
As the Hayabusa2 spacecraft studies the asteroid Ryugu and the OSIRIS REx mission closes in on the monster rock known as Bennu, a new study conducted by researchers in the US and the UK may revolutionize how we view the asteroid belt, as well as the meteors that impact Earth. According to the paper, published in Nature, the rocks in the inner asteroid belt are really fragments of a small handful of planets that were destroyed in the early days of the solar system, meaning that the majority of the meteorites that fall to Earth are chunks of these "lost" planets.

Scientists have known for years that a large portion of inner-belt asteroids (around 44%) came from one of five ancient planetary bodies, each of which formed a "family" of asteroids with similar compositions and orbits, but it turns out that percentage was off—in fact, almost all asteroids in the inner belt appear to be from a small group of destroyed planets, which probably numbered six in total.

According to astronomer Stanley Dermott, of the University of Florida: "Scientists have these wonderful collections of meteorites, and they're all slightly different. The big question was, 'Are these differences in the meteorites because they come from a large number of different objects, or because they come from a few objects that evolved over time?' We're saying these meteorites generally come from a small number of objects that were fairly large, hundreds of kilometers in diameter or more."

Apart from learning more about the origins of these asteroids, knowing that almost all of them come from a few sources helps the ongoing effort to protect Earth from a potentially cataclysmic impact. According to Dermott: "By learning more about how the asteroids have evolved over time, that helps us learn what they are made of, and knowing what a near-Earth asteroid is made of is going to be of big help if we want to know how to deflect it."
 
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