Asteroid Vesta. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

The cold, dead asteroid Vesta might have had a very active inner life early in the solar system’s history, according to an unusual analysis of a Saharan meteorite.

Vesta might have had a magma ocean underneath its rocky exterior, allowing bits of mineral to rise and fall between softer and harder layers of material, according to a study published online Sunday by the journal Nature Geoscience. If confirmed, that would make it more like Earth and the solar system’s other rocky planets than scientists had realized.

The report provides a fresh look at the protoplanet, supplementing data sent back from Vesta by NASA’s Dawn spacecraft.

“People think asteroids are big, gray, cold, almost potato-shaped lumps of rock that sometimes crash into the Earth and threaten us,” said study leader Beverley Tkalcec, a planetary geologist at Goethe University in Frankfurt, Germany. Instead, she said, “it has a dynamic interior similar to what might have been at the beginning of the Earth.”

Hot or not, Vesta is one big potato, about the size of Arizona. It was big enough to have experienced melting inside, causing the heavier material to sink to the center and the lighter stuff to rise to the crust.

Vesta and the dwarf planet Ceres – the next target for the Dawn spacecraft – represent planetary embryos that never fully formed. And since their rocks haven’t been chewed up by ongoing tectonic processes, as Earth’s have, they can be nearly as old as the solar system, which came into being more than 4.5 billion years ago.

Read more: Asteroid Vesta more like Earth than realized, study shows —

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