Weird ‘watermelonshaped’ asteroids like Dimorphos and Selam may finally have an explanation
Reported by Abha Jain
Most ‘moonlet’ asteroids are shaped like upright rugby balls, but Dimorphos was more like a squashed sphere
NASA
The unusual shapes of the tiny asteroids Dimorphos and Selam have perplexed astronomers for years, but a new study finally explains how they got so strange. It also suggests these bizarrely shaped ‘moonlets’ may be more common than scientists thought. Binary asteroids – pairs of asteroids that are essentially mini versions of the Earth-Moon system – are pretty common in our cosmic neighbourhood. These include the Didymos-Dimorphos duo that headlined NASA’s 2022 Double Asteroid Redirection Test (DART) mission. Previous research suggests that such binary asteroids form when a rubble-pile ‘parent’ asteroid composed of loosely held rocks spins so fast that it sheds some of its mass, which coalesces into the second, smaller satellite, or ‘moonlet’ asteroid.