A new analysis of a meteorite called Bunburra Rockhole has revealed that the rock originated from a previously unknown parent asteroid, allowing scientists to understand the geology of the parent body.

The parent body was differentiated, meaning that it was large enough to separate into a core, mantle and crust, and was roughly spherical in shape, though not as large as a planet. Identifying a new differentiated asteroid is vital for understanding the formation of asteroids and planets in the Solar System. Most of the large asteroids in the Asteroid Belt are already known, so this means that either the meteorite originated on an asteroid that has been eroded, or there is another large asteroid out there.

Bunburra Rockhole was the first meteorite to be recovered using the Desert Fireball Network, a network of cameras across Australia that observe where meteoroids enter the atmosphere. These cameras make it possible to determine the orbit of a meteorite prior to its descent to Earth. Models of the orbit of Bunburra Rockhole placed its origin within the innermost, main asteroid belt, interior to Vesta, the second-largest body in the Asteroid Belt between Mars and Jupiter.

The oxygen isotopes of a meteorite can act as a fingerprint to identify the parent body it originated from. The group of meteorites known as HED (howardite, eucrite, and diogenite) are thought to emanate from Vesta, as their oxygen isotope signatures are the same. Bunburra Rockhole was originally classed as a eucrite, however its oxygen composition is very different from that of the other HEDs.