Didymos
Didymos is a near-Earth binary asteroid, about 780 metres across, whose moon Dimorphos was struck by DART.
65803 Didymos is a near-Earth asteroid about 780 metres across, discovered in 1996. Its name is Greek for twin, because in 2003 astronomers found it has a small moon, now called Dimorphos, meaning 'having two forms'. Dimorphos orbits Didymos at a distance of about 1.2 kilometres.
The pair was the target of NASA's DART mission, which crashed into Dimorphos in September 2022 and shortened its orbit by about 32 minutes. Images taken just before impact showed Didymos as a diamond-shaped body and Dimorphos as an egg-shaped pile of boulders.
The system is an S-type asteroid, with a spectrum that suggests a composition similar to ordinary chondrites. Europe's Hera spacecraft is due to arrive in late 2026 to study the aftermath of DART's impact in detail, including the size of the crater and the mass of Dimorphos.
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Level: Explorer Ages 10 and up