Images of 42 of the Biggest Asteroids in the Solar System

An enormous team of astronomers has teamed up to make the European Southern Observatorys Very Long Telescope (ESOs VLT), the most sharpest ever view of 42 of the largest objects in asteroid belt between Mars and Jupiter.
The collection of images was published on the 42nd anniversary Douglas Adams' publication of The Hitchhikers Guide to the Galaxy. The number 42 in the book is the answer to the Ultimate Questions of Life, the Universe and Everything. These 42 images are some of the most sharp views of these objects that have ever been taken.

A great poster showing the asteroids is also available:

This poster features 42 of the largest asteroid belt objects, which are located between Mars (orbits not scaled). The outermost circle in this infographic was captured using the SpectroPolarimetric High Contrast Exoplanet REsearch instrument (SPHERE), which is part of ESO's Very Large Telescope. The sample includes 39 objects greater than 100 km in diameter and 20 objects larger than 200 km. A few of the objects are highlighted in the poster, including Ceres (the largest in the belt), Urania, Kalliope, and Lutetia. These were all visited by the European Space Agency's Rosetta mission. Credit to ESO. This link will take you to ESO, where you can see larger versions and other information.

Pierre Vernazza from the Laboratoire dAstrophysique de Marseille, France, led the asteroid study. He was also the one who published the results in Astronomy & Astrophysics. The asteroid study was conducted by Dawn and Rosetta, the European Space Agency's space missions. The sharp images from our ESO observations have been used to image 42 more targets.

Sixty-seven amateur astronomers participated in the project. The scientists stated that their primary goal was to be capable of reconstructing the 3D shapes and determining the density of the target asteroids. The extremely sensitive SpectroPolarimetric High-contrast Exoplanet REsearch instrument (SPHERE), mounted on the VLT was used by them.

The SPHERE data and light curve data were used to constrain the rotational parameters (spin and period). This has allowed us to construct a first 3D shape for every target, according to the paper.

According to Vernazza, ELT observations of main belt asteroids will enable us to study objects with diameters ranging from 35 to 80 km, depending on where they are located in the belt. We can also examine craters ranging in size from 10 to 25 km. A SPHERE-like instrument would allow us to image similar objects in the Kuiper Belt. This allows us to study the geological history and origins of larger numbers of smaller bodies.

We hope you enjoyed the 42 images we published today of asteroids. Now, we're trying to convince one our telescopes to get to work tonight. Turns out that installing Genuine People Personality software in telescopes is a bad idea ESO (@ESO) October 12, 2021

The majority of the 42 objects they sampled are more than 100 kilometers in size. In particular, nearly all the belt asteroids greater than 200 km were imaged by the team, 20 of 23. Ceres, Vesta and Vesta were the largest objects that the team investigated. They are approximately 940 and 520 km in diameter respectively. Urania and Ausonia are the smallest asteroids, measuring only 90 kilometers each.

The team discovered that most of the asteroids were divided into two distinct families when reconstructing their shapes. Some are perfectly spherical like Hygiea or Ceres. Others have an unusual, more extended shape such as Kleopatra, which is a dog-bone-shaped asteroids.

The 42 objects had different asteroids compositions, and the densities were computed. One theory that explains the differences in composition is that they originated from different parts of the Solar System. The results show that the most dense asteroids were formed in remote regions beyond Neptune's orbit and then migrated to their current location.

Learn more about how the teams work here.