It was found in 1807 by H. Olbers. It was first observed by the Hubble Telescope in December, 1994 and was proven to have a diameter of about 525 Km and a surface that is thought to be made of a deep impact crater and old lava flows. This information suggests that Vesta could once have had molten cores much like the Earth.

The main hypothesis about the origin of this asteroid suggests that small radioactive particles (such as the the isotope Aluminum-26) slowly gathered and stuck together. These radioactive particles probably came as a result of a supernova explosion in the nearby. The hot isotope may have melted the core, causing the asteroid to differentiate: heavier, dense material sank to the center while lighter rock rose to the surface. This is a common structure for the terrestrial planets, such as our Earth.

After Vesta's formation, molten rock flowed onto the asteroid's surface. This happened more than four billion years ago. The surface has remained unchanged since then. There is something else quite interesting in the history of Vesta, though. Its asymmetry and the shape of its south pole make scientists think that Vesta suffered a large impact event. Moreover, astronomers believe that fragments gouged out of Vesta during ancient collisions have fallen to Earth as meteorites, making Vesta only the fourth solar system object, other than Earth, the Moon and Mars, where scientists have a confirmed laboratory sample. (About 50-60 other meteorite types are suspected to have come from asteroids, but positive identifications are more difficult to make.)

Nowadays, most of the identified meteorites from Vesta are in the care of the Western Australian Museum. "The Hubble observations show that Vesta is far more interesting than simply a chunk of rock in space as most asteroids are," said Ben Zellner of Georgia Southern University. "This qualifies Vesta as the 'sixth' terrestrial planet." Before these observations, only the smaller and less geologically diverse asteroids, Ida and Gaspra, have been observed in detail by the Jupiter-bound Galileo spacecraft. Unlike Vesta, these smaller objects are pieces torn off larger bodies by collisions that occurred perhaps only a few hundred million years ago.

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Vesta -a planet?

Exploring Vesta

The name

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