Churyumov-Gerasimenko is the best-studied comet in existence: ESA’s Rosetta orbited it from 2014 to 2016 and set the Philae lander down on its surface - the first landing on a comet. The mission mapped a twin-lobed, duck-shaped nucleus so porous that it is fluffier than fresh snow, and watched it wake up as it approached the Sun.
Rosetta was the first spacecraft ever to orbit a comet, escorting it for two years.
Philae touched down on it in November 2014 - the first soft landing on a comet.
Its two lobes were once separate bodies that merged in a gentle ancient collision.
Tails point away from the Sun
A comet’s tail is not a wake trailing behind its motion. Sunlight and the solar wind push escaping gas and dust directly away from the Sun, so the tail always streams anti-sunward - which means that on the outbound half of its orbit a comet travels tail-first. Rosetta saw this from the inside, riding alongside 67P as its jets switched on and bent away from the Sun.
Physical characteristics
Diameter
4 km
Dimensions
4.3 × 4.1 km
Mass
1.000e+13 kg
Density
0.53 g/cm³
Rotation period
12.4 h
Geometric albedo
0.06
Atmosphere and composition
Atmosphere
A coma of water vapour, CO₂ and dust near perihelion; Rosetta flew inside it for two years.
Composition
Roughly 70% empty pore space: fluffy dust, water and CO₂ ices, and complex organics including the amino acid glycine.
Orbit and activity
Perihelion distance
1.24 AU
Aphelion distance
5.68 AU
Origin
Jupiter-family comet from the Kuiper belt
Last perihelion
2 Nov 2021
Next perihelion
~Apr 2028
Discovery
Discovered by
Klim Churyumov & Svetlana Gerasimenko
Year
1969
How
found on photographic plates taken during a comet survey in Alma-Ata
After a 10-year chase, Rosetta became the first spacecraft to orbit a comet, escorting 67P/Churyumov-Gerasimenko around the Sun. Its lander Philae made the first-ever touchdown on a comet in November 2014.