Observing

See asteroid 2 Pallas at its best during August 2016

During the Perseid meteor shower, second-largest asteroid 2 Pallas passed close to the southeast of globular cluster Messier 15 in the constellation of Pegasus. The minor planet still lies in the vicinity of this beautiful deep-sky object, reaching opposition on 20 August — here’s our in-depth guide to Pallas at its best.

News

Dawn’s gravity data probes interior of dwarf planet Ceres

By tracking subtle changes in the motion of NASA’s Dawn spacecraft, scientists have mapped the variations in Ceres’ gravity for the first time, providing clues to the dwarf planet’s internal structure. The new data suggest that Ceres has a weak interior, and that water and other light materials partially separated from rock during a heating phase early in its history.

News

The case of the missing Ceres craters

Ceres is covered in countless small, young craters, but none are larger than 175 miles (280 kilometres) in diameter. To scientists, this is a huge mystery, given that the dwarf planet must have been hit by numerous large asteroids during its 4.5 billion-year lifetime. Where did all the large craters go?

News

Small asteroid is Earth’s constant companion

A small asteroid designated 2016 HO3 has been discovered in an orbit around the Sun that keeps it as a constant companion of Earth, and it will remain so for centuries to come. It is too distant to be considered a true satellite of our planet, but it is the best and most stable example to date of a near-Earth companion, or “quasi-satellite.”