Asteroid Vesta, once thought to be a protoplanet that had been left behind in its formation, is now the subject of a groundbreaking investigation of what may be a remnant of a far larger planet that was present in the early solar system. New research, spearheaded by scientists at Michigan State University and published in Nature Astronomy in April 2025, challenges previous assumptions about Vesta being an embryonic planet, made based on observations from NASA’s 2012 Dawn mission. The research instead suggests that Vesta may have been ejected from another, now-extinct planet in a massive collision some 4.5 billion years ago.
Asteroid Vesta reveals surprising new insights about its structure
The new research contradicts the old hypothesis that Vesta is an undifferentiated embryonic planet. Seth Jacobson, the lead author at Michigan State University, explained that the new data indicate the interior of Vesta is not in accordance with the fully differentiated planet model. This is an unusual interpretation of planetary science as it contradicts past research that suggested that Vesta might possess a dense metal core—a characteristic of differentiated planetary bodies.The research conclusions are based on precise gravity data obtained from the radio Doppler signals bounced back by the Dawn spacecraft. Using advanced calibration techniques, scientists found no sign of the metal-rich core that earlier research had indicated. The lack of core differentiation suggests that Vesta never existed as a fully formed planet. Instead, the evidence is for a scenario where Vesta is a fragment of a larger, older planet that was shattered in a gigantic collision billions of years ago.
Vesta’s volcanic features raise questions about its geologic origins
However, Vesta’s surface remains a mystery. The asteroid features evidence of volcanism, including a basaltic surface typical of bodies that have differentiated to a significant geological degree. But the absence of a differentiated interior calls into question the mechanism responsible for this activity. Jacobson assumes that Vesta could have experienced volcanic activity without complete differentiation, and this would mean that it retains some internal homogeneity that contradicts the earlier prediction for a planet-sized body.The study results offer a new explanation of the geologic features of Vesta. The volcano-formed surface of the asteroid may not be the result of a shared process of planetary evolution. Instead, Jacobson and co-workers propose that Vesta was created from a cataclysmic planetary impact-generated debris. According to this hypothesis, Vesta could have been created from a fully differentiated planet whose fragments now occupy the asteroid belt.
Vesta’s surprising features redefine planetary evolution
This idea also paves the way for a broader theory: Vesta is merely one asteroid that is the product of such an impact. Other asteroids in the solar system could also be the remains of larger, disintegrated planets. This could be supported by future scans for gravity by NASA’s Psyche mission and the European Space Agency’s Hera mission, which are scheduled to find out more about asteroids and what planetary remains are made of.Vesta’s makeup would imply a shared origin with Earth or other early planetary bodies. If that is the case, it would be a revolutionary break in asteroid science. Vesta’s own features, such as its volcanic crust and lack of heavy core, contradict conventional thinking and imply that it might have had an earlier life in a more extensive planetary system, like early Earth or other terrestrial planets.
What is Vesta
Vesta is the second largest body in the asteroid belt and represents close to 9% of the total mass of all the asteroids in the belt. The only body smaller than it is Ceres, the largest asteroid in the asteroid belt, which is a dwarf planet. It was discovered by German astronomer Heinrich Wilhelm Olbers in 1807. It was believed to be a piece of a planet that had been destroyed. It was the fourth to be discovered, and it was named by German mathematician Carl Friedrich Gauss after the Roman goddess of home and hearth. From July 2011 to September 2012, NASA’s Dawn spacecraft orbited Vesta, accumulating critical data before heading to dwarf planet Ceres. Vesta is almost spherical and almost counted as a dwarf planet. Vesta is different from most other asteroids in that it is differentiated, i.e., it possesses a core, mantle, and crust, just like the terrestrial planets.Its surface exhibits the largest range of brightness of any solid solar system object, with dark spots believed to be residue of ancient asteroid impacts, and brighter areas made of native rocks.Also Read | Indian astronaut Shubhanshu Shukla to interact with students live from the ISS this June and conduct five additional experiments with NASA
