(65803) Didymos I Dimorphos (provisional designation S/2003 (65803) 1) is a minor-planet moon of the near-Earth asteroid 65803 Didymos. It has a diameter of 170 metres (560 ft) and has been called a low-density rubble pile. It was discovered in 2003 at the Ondřejov Observatory.
Dimorphos was the target of the Double Asteroid Redirection Test (DART), a NASA space mission that crashed with the moon in September 2022 on purpose.[1][2] The ESA mission Hera is planned to arrive at the Didymos system in 2026 to further study the effects of the collision on the moon.