Vesta, once considered an asteroid too big to be ordinary yet small enough not to be called a planet, has had its scientific status upended. A new study led by the NASA Jet Propulsion Laboratory re-examined data from the Dawn spacecraft and found that Vesta’s internal structure is almost uniform throughout.
The research team looked at the moment of inertia, a property that governs an object’s mass distribution and spin in space. They discovered that Vesta spins more sluggishly than expected, contradicting earlier models that required a substantial iron-nickel core.
The study also used refined calibration methods to analyze Dawn’s gravity and imaging records. The results show that Vesta’s history is far more complex than previously believed, shaped by unique processes such as interrupted planetary differentiation and late-stage collisions.
Two competing ideas now vie to explain Vesta’s true nature. One option suggests that Vesta froze in mid-stride of its own planetary differentiation process, while the other proposes that it was a fragment blasted off a larger world during the solar system’s chaotic youth.
The findings have significant implications for our understanding of Vesta and the early solar system. Whether Vesta is an unfinished embryo or a shard from a primordial planet, its story now looks like a complex detective mystery spanning 4.5 billion years.
Source: https://www.earth.com/news/asteroid-vesta-may-be-a-fragment-of-a-lost-world