Asteroid Vesta may be a Leftover From an Early Planet

Vesta, a large asteroid in our solar system, might be a fragment of an ancient planet shattered by a massive collision 4.5 billion years ago, according to research led by Seth Jacobson of Michigan State University and published in Nature Astronomy.

Scientists are still fascinated by the origins of asteroid Vesta’s formations.
An asteroid that landed on Earth in 2018 might have resulted from collisions involving Vesta.

More Than Just a Protoplanet?

Vesta, with a diameter of 525 km, is the second-largest object in the Asteroid Belt. Previously, scientists viewed it as a protoplanet—a rocky body from the early Solar System that never fully developed into a planet. However, if the new study’s findings are accurate, Vesta’s true nature may be something different.

In this study, researchers analyzed Vesta’s gravitational field and its movement through space—data that could indicate whether the asteroid has a dense core or a more uniform internal structure. A 2012 analysis had suggested that Vesta possessed its own core, supporting the idea that it was a protoplanet.

However, the new study revealed something unexpected: Vesta lacks a dense core. “The absence of a core was quite surprising. It changes the way we think about Vesta,” said Jacobson. The challenge is that Vesta’s surface materials, formed by volcanic activity, would usually generate enough heat for heavier elements to sink and create a core.

Yet, gravitational data indicate that this process never occurred. At the same time, some asteroids originating from Vesta display features that support the volcanic theory. Jacobson suggests two possible explanations: Vesta began differentiation, but the process was halted.

Vesta as a Fragment of a Planetary Impact

The other explanation—Jacobson’s preferred theory—suggests that Vesta was torn from a planet during a massive impact. If the asteroid originated from a differentiated planet with widespread volcanic activity, that would account for the presence of volcanic rocks on Vesta without it having undergone differentiation itself.

If Vesta truly came from another planet, it raises the possibility that other asteroids are also fragments of ancient planets, potentially reshaping our understanding of asteroid origins.

“The Vesta collection is no longer just debris from a body that failed to become a full-fledged planet,” Jacobson said. “These meteorites might be remnants of an ancient planet in its early stages of formation. But we still don’t know which planet that was,” he added.

Read the original article on: Canaltech

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