42 in one fell swoop
The largest asteroids seen by the Very Large Telescope
The largest asteroids seen by the Very Large Telescope
The Very Large Telescope (VLT) of the European Southern Observatory ESO in Chile and the precision spectrograph SPHERE captured these detailed images of 42 of the largest objects in the asteroid belt between the orbits of Mars and Jupiter. By far the largest celestial body in this region of the solar system is the dwarf planet (1) Ceres, which accounts for about a quarter of the total mass of the asteroid belt. It has an average diameter of 950 kilometers, less than a third of the moon's diameter. The next largest are the asteroids (4) Vesta and (2) Pallas at about 500 kilometers in size.
If you take a closer look at the images, the large objects usually show a spherical shape, while the smaller celestial bodies have an irregular, potato-like shape. The smaller bodies were reshaped by impacts from other objects. Some are also fragments of larger primordial bodies in the asteroid belt that broke apart in collisions. The asteroid (216) Cleopatra, which resembles a dog bone in some pictures, has a particularly bizarre shape. Only three of these celestial bodies have been visited by a spacecraft: Ceres, Vesta and Lutetia. There are detailed close-up shots of these objects. They are suitable for assessing the quality of the images from SPHERE. In four years, hopefully, close-up images of the asteroid (16) Psyche will be added when NASA's eponymous probe reaches it in 2026. In order to be able to make such detailed images at all, the full resolution of one of the VLT's 8.2 meter telescopes had to be used. The adaptive optics of SPHERE eliminated the air turbulence. But even then, complex image processing was required to make the details visible. The SPHERE images are a foretaste of what will be possible with ESO's upcoming Extremely Large Telescope. Then, for example, distant objects in the Kuiper Belt could be photographed with a similar quality.
