Credit: NASA/Johns Hopkins APL/Southwest Research Institute Public Domain — NASA Media Usage Guidelines

KUIPER BELT OBJECT

Arrokoth

The most distant object ever visited by spacecraft — a contact-binary cold classical KBO.

Also known as: 2014 MU69, Ultima Thule (informal, now retired)

Orbits Sun

About Arrokoth

486958 Arrokoth is a “cold classical” Kuiper Belt Object that on 1 January 2019 became the most distant object ever visited by a spacecraft — NASA’s New Horizons flew within 3,500 km at 6.6 billion km from Earth. Arrokoth is a contact binary: two distinct lobes (nicknamed Ultima and Thule) that gently merged together in the Solar System’s earliest days. Its pristine surface has been preserved at ~40 K for 4.5 billion years, making it the best sample we have of the primordial Solar System.

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

Physical Properties

Mean radius18 km

Rotation period15.92 h

Bond albedo0.21

Orbit

OrbitsSun

Semi-major axis44.581 AU

Eccentricity0.0416

Inclination2.4512°

Orbital period297.67 yr

Missions to Arrokoth

1 spacecraft tracked on Space Launch Live.

Gallery

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

The Kuiper Belt object Arrokoth, imaged by New Horizons on 1 January 2019. NASA/Johns Hopkins APL/Southwest Research Institute · 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.