Knocked out of a planet? – Surprising finding about asteroid Vesta

Versta, the second-largest asteroid in the asteroid belt, may not be a protoplanet, as previously assumed, but it is still not a real asteroid either. This was determined by a research team using data from NASA's Dawn spacecraft, which orbited the celestial body between 2011 and 2012. Their analysis has now revealed that Vesta has no core at all and that its interior does not resemble that of a planet. At the same time, however, unlike on asteroids, there is volcanic basalt there. This throws assumptions about the formation of Vesta out the window, as it was previously assumed that it was a protoplanet that never fully developed. Now other explanations are needed. The team has hypotheses.

Remnant of a nascent planet?

Vesta, or actually (4) Vesta, is the second-largest asteroid in the main belt between Mars and Jupiter with a diameter of around 500 kilometers after (2) Pallas. Only Ceres is even larger, but it is a dwarf planet. Until now, it was assumed that Vesta has a crust, a mantle and a core, the Michigan State University explains. However, the research team led by planetologist Seth Jacobson has now determined that this core does not exist at all. This was very surprising and requires an entirely new way of thinking about the celestial body. It is therefore not the product of an aborted planet formation.

According to the research team, it is conceivable that Vesta once started the process in which the layers are formed by melting processes, but that this process was interrupted. The team does not specify the possible causes for this. As a second theory, they suggest that Vesta could be a chipped piece of a growing planet from the early days of the solar system. Jacobson has already investigated whether there are such remnants in the main asteroid belt. He is therefore particularly pleased that a large remnant has now possibly been found in Vesta. "We just don't yet know from which planet," he says.

The analysis now presented in the journal Nature Astronomy is based on the precise measurement data from Dawn. In terms of rotation and gravitational field, the celestial body did not behave like an object with a core. However, this finding required almost ten years of refining the calibration and processing techniques for the data. Only now has it been possible to explain the previously contradictory gravity data. Further modeling is now possible to reconstruct the evolutionary history of Vesta. Further findings might be hidden in the Dawn data, which can be brought to light using new methods.

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