Dimorphos

Dimorphos is a satellite asteroid of the larger asteroid Didymos. The two asteroids comprise a binary asteroid system within the solar system, with Dimorphos accounting for roughly 1% of the mass of the system.

Properties

Dimorphos is roughly 160 meters (520 feet) in diameter. It orbits Didymos about every 12 hours, with an orbital radius of approximately 1.6 kilometers (1.0 mile).

References

Info from NASA: https://solarsystem.nasa.gov/asteroids-comets-and-meteors/asteroids/didymos/in-depth/

Info from the European Space Agency (ESA): https://www.esa.int/Safety_Security/Hera/Target_asteroid2