67P/Churyumov–Gerasimenko
What is 67P/Churyumov–Gerasimenko?
Comets· Nucleus 4.3 × 4.1 km. The first comet to be orbited by a spacecraft and to have a lander set down on it. Europe's Rosetta mission watched it up close for more than two years.
Orbit and period
| Nucleus | 4.3 × 4.1 km (duck-shaped, two lobes) |
|---|---|
| Period | 6.45 yr |
| Distance | 1.24~5.68 AU |
| Mission | Rosetta orbiter 2014–16, Philae lander |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Why 67P's water doesn't match Earth's oceans
Where Earth's oceans came from is an old question. One idea is that comets striking the young Earth delivered the water. One way to test this is to compare the share of 'heavy hydrogen' in water, because it differs depending on where the water formed and so works like a birthplace label.
Rosetta measured this ratio in the water vapour coming off 67P and found it more than three times that of Earth's oceans. This suggests that comets like 67P were not the main source of our seas. But in 2011 the Herschel Space Observatory found that the water of Comet Hartley 2 matched Earth's. So the question now is which kind of comet might have brought water, and the idea that asteroids delivered it has gained support.
Rosetta was named after the Rosetta Stone, the key to reading Egyptian hieroglyphs, and the lander Philae after the Nile island where an obelisk used in that work was found. So regions on the comet were named after ancient Egyptian gods and figures such as Ma'at, Imhotep and Hapi. Philae's exact resting place was confirmed only on 2 September 2016, in a Rosetta photograph.
The comet in depth
Comet 67P/Churyumov–Gerasimenko was discovered in 1969 by the Soviet astronomer Klim Churyumov on a photographic plate taken by his colleague Svetlana Gerasimenko. It travels between 1.24 and 5.68 AU from the Sun and goes around once every 6.45 years. Before a close pass by Jupiter in 1959 it did not come this near the Sun and was a much fainter comet.
In August 2014 the European Space Agency's Rosetta spacecraft arrived after a ten-year journey. It found a nucleus of two joined lobes, shaped like a rubber duck and measuring 4.3 km by 4.1 km. In November the lander Philae touched down, but the harpoons meant to anchor it failed to fire. It bounced twice and came to rest under a shady cliff, sending back data for about 60 hours until its battery ran out.
For more than two years Rosetta watched the comet spout gas and dust as it neared the Sun. It found oxygen molecules and the amino acid glycine around the comet. On 30 September 2016 Rosetta ended its mission by gently settling onto the surface. In the orbit view you can see a small ellipse that dips inside Mars's orbit and reaches a little beyond Jupiter's.
Frequently asked
- How long is the orbital period of 67P/Churyumov–Gerasimenko?
- The period of 67P/Churyumov–Gerasimenko is 6.45 yr.
- How far is 67P/Churyumov–Gerasimenko from Earth?
- The distance of 67P/Churyumov–Gerasimenko is 1.24~5.68 AU.
- In one line, what is 67P/Churyumov–Gerasimenko?
- Comets — The first comet to be orbited by a spacecraft and to have a lander set down on it.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.