Asteroids are small solid objects circling around the Sun, following orbits located mainly in the so-called “asteroid belt”, an ill-defined region between Mars and Jupiter. Antoine de Saint-Exupéry’s most famous character, the Little Prince, lived on a volcanic asteroid whose volcanoes the Prince took care of.
But it is believed that real asteroids are seldom volcanic. A volcanic or, more properly, basaltic asteroid, forms only if the body has melted partially during its history, allowing heavy elements (metals) to sink towards its centre, leaving lighter rocks on the mantle, and forming a volcanic crust of basalt through emission of lava flows. This process is called differentiation, and an asteroid has to be quite large for it to happen.
Only one big asteroid shows a basaltic crust, Vesta, and there is a complete family of smaller objects showing similar surface and orbital characteristics, thought to be fragments taken away from Vesta by large impacts: these asteroids constitute the “Vesta family.” However, there are reasons to expect that these objects should not be so scarce. Astronomers think that there should have existed many clones of Vesta in the old Solar System, and some of them or, at least, some of their fragments, could still be out there.
Recent studies have discovered that several tiny near-Earth asteroids are basaltic and they are not necessarily lost members of the Vesta family. Furthermore, a basaltic asteroid, Magnya, was found in the outer part of the asteroid belt in 2000.
The Little Prince lived on asteroid B612, bearing three volcanoes and one rose. Real volcanic asteroids are already here. But, where are the roses?
Credit: Calar Alto Observatory