A fragment of a meteorite indicates a missing dwarf planet in the early solar system

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Every asteroid that falls to Earth is a potential window into the origin of the solar system, but scientists have come across something quite strange while studying a fragment of the asteroid Almahata Sitta. It contains evidence of a huge, previously unknown object in our solar system – perhaps a long-destroyed dwarf planet.

The Almahat Sitta asteroid collection consists of about 600 fragments, all of which rained on Sudan in 2008 when a space rock known as the 2008 TC3 exploded. This was the first asteroid strike that scientists accurately predicted, giving teams on Earth the opportunity to crash and collect a large amount of material from a 4-meter object.

Planetary geologist Vicky Hamilton led a new analysis of Almahat Sitt material at the Southwestern Research Institute. Hamilton’s team received a 50-milligram sample of an asteroid (AhS 202) for testing. They mounted and polished the tiny debris and examined its composition with an infrared microscope. Inside AhS 202, the team found something unexpected – a remarkable rare hydrated crystal known as amphibole. This simply wasn’t supposed to be part of the 2008 TC3.

These silicate crystals only form due to prolonged exposure to high pressure and temperatures, which would never happen in space rocks like 2008 TC3 or other carbon chondritic meteorites of similar size. According to the study, the only conclusion that fits into what we know about amphiboles is that in 2008 TC3 was once part of a much larger facility. The researchers estimate that the parent body was approximately similar to the dwarf planet Ceres, which measures 939 kilometers (583 miles) in diameter.

Micrography on amphibole crystals, orange.

It is obvious that we have not lost track of any rocks the size of a planet hovering around the inner solar system. It is theoretically possible that there is still an undiscovered Cerera-sized asteroid in the outer solar system that created the 2008 TC3, but that is an external chance. Researchers believe that the parent body is more likely to have disintegrated a long time ago. And if it had happened once, it could have happened many times.

The study concludes that fragments of the Almahata Sitta could provide insight into a previously unknown phase in the formation of our solar system. This mysterious dwarf planet existed long enough to leave its geological trace, and then for some reason disintegrated. It’s something we probably want to understand better.

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