Asteroid the size of a small planet in our solar system

Scientists studying a sharp meteorite have found evidence that it comes from a previously unknown asteroid that may be as large as the dwarf planet Ceres. The meteorite, Almahata Sitta (AhS), fell on Earth in 2008 and the researchers studied its composition to learn about the asteroid from which it came.

A meteorite is the name for a piece of debris that falls on the earth, and this particular comes from an asteroid, a small object orbiting the sun. Asteroids are usually much smaller than planets and are mostly grouped in the asteroid belt between Jupiter and Mars. Within this asteroid belt, the largest known object is a dwarf planet called Ceres.

The new evidence suggests that another asteroid as large as Ceres may exist elsewhere in the solar system.

SwRI scientists studied the composition of a small shard of a meteoroid to determine that it was probably derived from a previously unknown parent asteroid.  This color-coded photomicrograph of the meteoroid sample shows the unexpected amphibole crystals identified in orange.
SwRI scientists studied the composition of a small shard of a meteoroid to determine that it was probably derived from a previously unknown parent asteroid. This color-coded photomicrograph of the meteoroid sample shows the unexpected amphibole crystals identified in orange. Thanks to NASA / USRA / Lunar and Planetary Institute

The researchers from the Southwest Research Institute (SwRI) looked at a small sample of meteorite AhS to learn about the body from which it came. “We were given a sample of 50 mg AhS to study,” said Dr. Vicky Hamilton, first author of the article, explained in a statement. ‘We mounted and polished the small shard and used an infrared microscope to examine its composition. Spectral analysis identified a range of hydrated minerals, particularly amphibole, indicating intermediate temperatures and pressures and a prolonged period of aqueous change on a parent steroid of at least 400 and up to 1100 kilometers in diameter. ”

This means that the asteroid from which the sample came had to be large and that it formed in the presence of water. It is rare to find the mineral amphibole in this type of meteorite, a carbonaceous chondrite (CC) meteorite, which makes AhS an unusual sample and is especially useful for learning more about the early solar system.

We could possibly learn more about the early solar system from the study of two recently visited asteroids, Ryugu and Bennu. Ryugu was visited by the Japanese Hayabusa 2, which recently returned a monster to Earth, and Bennu was visited by OSIRIS-REx from NASA, who would have to return a monster in 2023.

These monsters, collected directly from asteroids, may differ from those like AhS that fell on Earth and were affected by their journey through the atmosphere.

“If the compositions of the Hayabusa2 and OSIRIS-REx samples differ from what we have in our collection of meteorites, it could mean that their physical properties prevent them from surviving the processes of ejection, transit and access through the Earth’s atmosphere. not, at least in their original geological context, ”Hamilton said. “However, we think there is more carbonaceous chondrite material in the solar system than our collection of meteorites suggests.”

The findings are published in the journal Nature.

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