67P/Churyumov-Gerasimenko

Comet· orbits the Sun

67P/Churyumov–Gerasimenko is a two-lobed, 'rubber-duck'-shaped comet studied in unprecedented detail by ESA's Rosetta orbiter and its Philae lander in 2014–2016.

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Key facts

Perihelion

1.21 AU

Aphelion

5.71 AU

Orbital period

6.43 years

Eccentricity

0.6495

Science

Physical

Nucleus: ≈ 4.3 × 4.1 km (two lobes)
Composition: A dark, porous nucleus of water, carbon-monoxide and carbon-dioxide ices mixed with dust and organic-rich material — extremely low density.

Orbital

Semi-major axis: 3.46 AU; From catalogued orbital elements (MPC)
Eccentricity: 0.6495; From catalogued orbital elements (MPC)
Inclination: 3.87 °; From catalogued orbital elements (MPC)
Orbital period: 6.43 years; From catalogued orbital elements (MPC)
Perihelion: 1.21 AU; Computed from the orbital elements
Aphelion: 5.71 AU; Computed from the orbital elements
Mean orbital velocity: 16 km/s; Computed from the orbital elements

Activity

Status: Currently inactive (q = 1.21 AU, next perihelion ≈ 2028)
Becomes active within: 5 AU of the Sun

Radiation & temperature

Insolation: 0.0836 S⊕ · 8% of the sunlight Earth receives; Computed from the distance to the Sun (inverse-square; Earth's sunlight = 1), before any atmosphere.
Geometric albedo: 0.06; Nucleus geometric albedo ≈ 0.06 — a very dark surface (Rosetta).
Equilibrium temperature: 147 K (-126 °C); Computed from albedo + distance from the Sun (airless black body); uses the geometric albedo as an estimate

Discovery & history

Discovered: September 20, 1969
By: Klim Churyumov and Svetlana Gerasimenko
Method: Photographic plates
Name: Named after its two discoverers at the Alma-Ata (Almaty) observatory, Kazakhstan.

67P was discovered in 1969 by Klim Churyumov while examining a photographic plate of another comet taken by Svetlana Gerasimenko at Alma-Ata (now Almaty), Kazakhstan. In 2014 it became the first comet ever orbited and landed upon: ESA's Rosetta spacecraft arrived after a ten-year chase and released the Philae lander onto its surface, revealing a dark, two-lobed 'rubber-duck' nucleus of ice and dust.