Didymos

The primary of a binary asteroid system — target of NASA's DART planetary-defense test.

Orbits Sun 1 moons

Primary of the first binary asteroid system targeted by a spacecraft.
Its moon Dimorphos was struck by NASA's DART spacecraft on 26 September 2022.
Target of ESA's Hera mission (launched October 2024, arrival December 2026).

About Didymos

Didymos is a near-Earth asteroid and the primary of a binary asteroid system. Its 170 m moonlet Dimorphos was the target of NASA’s Double Asteroid Redirection Test (DART), which impacted Dimorphos on 26 September 2022 to demonstrate that kinetic impactors can change an asteroid’s orbit — a planetary-defense technique. The impact shortened Dimorphos’s orbital period around Didymos by 33 minutes. ESA’s Hera spacecraft, launched 7 October 2024, will arrive in December 2026 to characterize the system post-impact in detail.

Live · 3DSee Didymos in the Live 3D Solar SystemFly to Didymos and explore its orbit among the planets, moons & spacecraft in a full-screen interactive view.Launch 3D view

Physical Properties

Mean radius0 km

Rotation period2.26 h

Bond albedo0.15

Orbit

OrbitsSun

Semi-major axis1.644 AU

Eccentricity0.384

Inclination3.41°

Orbital period2.11 yr

Notable Moons

Gallery

Hand-picked mission imagery of Didymos sourced from NASA and partner archives. Click any photo for full resolution and source attribution.

Asteroid Didymos (top) and its moonlet Dimorphos, the last DART/DRACO image showing both bodies in full before impact. NASA/Johns Hopkins APL · Public Domain u2014 NASA Media Usage Guidelines

Imagery on this page is provided by the original mission teams. Full attribution terms: Image Rights & Credits.

Sources & Further Reading

Numerical values (radius, mass, orbital elements, temperatures) are drawn from NASA NSSDC Planetary Fact Sheets, JPL Horizons, and the JPL Small-Body Database. Last refreshed: 2026-06-08 01:37:02.