65803 Didymos and 65803-1 Dimorphos

Asteroid Didymos and its small moonlet Dimorphos make up what’s called a "Binary Asteroid System" – meaning the small moon (Dimorphos) orbits the larger body (Didymos).

The two asteroids are not a threat to Earth, but because they do pass relatively close to Earth, they were chosen as the target for NASA’s Double Asteroid Redirection Test (DART) mission – the agency's first mission to test planetary defense technology. This technology could one day be used to deflect hazardous asteroids on a collision course with Earth.