16 Psyche

Asteroid· orbits the Sun

16 Psyche is an unusually metal-rich asteroid, thought to contain large amounts of iron–nickel metal — possibly the exposed core of a shattered protoplanet. NASA's Psyche spacecraft, launched in 2023, arrives in 2029.

Open in 3D viewSee 16 Psyche in the live, interactive 3D map

Key facts

Radius

111 km

2% of Earth's radius

Distance from Sun

2.93 AU

Orbital period

5.00 years

Eccentricity

0.1349

Rotation

4.20 hours

Science

Physical

Mean radius: 111 km · 2% of Earth's radius
Mass: 2.40 × 10¹⁹ kg · 0.000327 Moon masses
Density: 4,187 kg/m³ · 4.2× water; Computed from mass and radius
Rotation period: 4.20 hours

Orbital

Semi-major axis: 2.93 AU; From catalogued orbital elements (MPC)
Eccentricity: 0.1349; From catalogued orbital elements (MPC)
Inclination: 3.10 °; From catalogued orbital elements (MPC)
Orbital period: 5.00 years; From catalogued orbital elements (MPC)
Perihelion: 2.53 AU; Computed from the orbital elements
Aphelion: 3.32 AU; Computed from the orbital elements
Mean orbital velocity: 17.4 km/s; Computed from the orbital elements

Discovery

Discovered: March 17, 1852
Discoverer: Annibale de Gasparis

Composition

Make-up: An M-type body rich in iron–nickel metal mixed with rock — possibly the remnant core of a disrupted protoplanet, to be confirmed by the Psyche mission.

Radiation & temperature

Insolation: 0.117 S⊕ · 12% of the sunlight Earth receives; Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
Geometric albedo: 0.16; Geometric (V-band) albedo; Bond albedo not directly measured.
Equilibrium temperature: 156 K (-117 °C); Computed from albedo + distance from the Sun (airless black body); uses the geometric albedo as an estimate

Discovery & history

Discovered: March 17, 1852
By: Annibale de Gasparis
Method: Visual discovery (telescopic)
Name: Psyche, the personification of the soul in Greek myth, beloved of Eros.

16 Psyche, found in 1852, is the largest of the metal-rich 'M-type' asteroids and may be the exposed iron core of a shattered protoplanet. NASA's Psyche spacecraft launched in 2023 and arrives in 2029 to study it — humanity's first visit to a world made largely of metal rather than rock or ice.

Images

Asteroid 16 Psyche, imaged by the VLT's SPHERE instrument — ESO / LAM (CC BY 4.0) · Wikimedia Commons

A Metal-Rich World (Artist's Concept) — NASA/JPL-Caltech/ASU · NASA Image Library

Artist's Concept of Psyche Spacecraft with Five-Panel Array — NASA/JPL-Caltech/Arizona State Univ./Space Systems Loral/Peter Rubin · NASA Image Library

Psyche Spacecraft (Artist's Concept) — NASA/JPL-Caltech/ASU · NASA Image Library

Asteroid Psyche (Illustration) — NASA/JPL-Caltech/ASU · NASA Image Library

Images from open archives · credit shown per image