67P/Churyumov–Gerasimenko
First comet orbited and landed upon by spacecraft.
67P/Churyumov–Gerasimenko (often shortened to 67P or 67P/C–G, and nicknamed "Chury") is a comet from the Jupiter family that originally came from the Kuiper belt. As of 2012, it takes about 6.45 years to orbit the Sun, spins once every 12.4 hours, and can reach a top speed of 135,000 km/h (38 km/s). Its longest and widest dimensions are roughly 4.3 by 4.1 kilometers. The comet was first spotted on photographic plates in 1969 by Soviet astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko, who it is named after. Its most recent closest approach to the Sun (perihelion) occurred on 2 November 2021, and the next will be on 9 April 2028.
This comet was the target of the European Space Agency's Rosetta mission, launched on 2 March 2004. Rosetta caught up with 67P on 6 August 2014 and entered orbit around it on 10 September 2014. The mission's lander, Philae, touched down on the comet's surface on 12 November 2014, becoming the first spacecraft ever to land on a comet nucleus. Rosetta itself ended its mission by landing on the comet's Maʽat region on 30 September 2016.
**Discovery** The comet was discovered in 1969 by Klim Ivanovich Churyumov of Kyiv University's Astronomical Observatory. He was examining a photograph taken for the comet Comas Solà by Svetlana Ivanovna Gerasimenko on 11 September 1969 at the Alma-Ata Astrophysical Institute, near Alma-Ata (then the capital of the Kazakh Soviet Socialist Republic). Churyumov noticed a cometary object near the plate's edge and initially thought it was Comas Solà. Back at his institute in Kyiv, he studied all the plates more carefully. On 22 October, about a month after the photo was taken, he realized the object couldn't be Comas Solà because it was about 1.8 degrees off where it should have been. A closer look revealed a faint image of Comas Solà at its expected position, proving the other object was a different body.
**Shape** The comet has two lobes joined by a narrower neck. The larger lobe measures about 4.1 km by 3.3 km by 1.8 km, and the smaller one about 2.6 km by 2.3 km by 1.8 km. With each orbit, the comet loses material as gas and dust are evaporated by the Sun; as of 2015, it loses an average layer about 1 ± 0.5 meters thick per orbit. Its mass is roughly 10 billion tonnes. The two-lobe shape came from a gentle, low-velocity collision of two objects, making it a contact binary.
Quick Facts
- Pronounced
- ch · Vr · i · ' · u: · m · Q · f · _ · dZ · Er · , · ae · s · i · ' · m · E · N · k · ou · ,_ · , · g · Er · @ · s · i · -
- Discoverer
- Klim Ivanovich Churyumov / Svetlana Ivanovna Gerasimenko
- Discovered
- 20 September 1969
- Discovery Site
- Almaty, Kazakh SSR, Soviet Union / Kyiv, Ukrainian SSR, Soviet Union
- Epoch
- 25 February 2023 (517-215-2427)(JD 2460000.5)
- Aphelion
- 5.704 AU / ( · )
- Perihelion
- 1.210 AU / ( · )
- Semimajor
- 3.457 AU / ( · )
- Eccentricity
- 0.64989
- Period
- 6.43 yr
- Inclination
- 3.8719°
- Asc Node
- 36.33°
Facts from the source article.
Lore & Background
The comet was discovered in 1969 by Soviet astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko. Churyumov examined a photographic plate exposed for comet Comas Solà by Gerasimenko on 11 September 1969 at the Alma-Ata Astrophysical Institute. He initially assumed the cometary object near the plate's edge was Comas Solà, but on 22 October he found it was about 1.8 degrees off the expected position; a faint image of Comas Solà at its expected position proved the other object to be a different body.
The comet consists of two lobes connected by a narrower neck, forming a contact binary from a gentle, low-velocity collision. The larger lobe measures about 4.1 km × 3.3 km × 1.8 km and the smaller about 2.6 km × 2.3 km × 1.8 km. With each orbit the comet loses matter; a layer with an average thickness of about 1 ± 0.5 m is lost per orbit as of 2015. There are 26 distinct regions on the surface, each named after an Egyptian deity—gods on the large lobe, goddesses on the small lobe. Features called gates were named after deceased members of the Rosetta team. The largest boulder, Cheops, measures up to 45 meters and is located on the larger lobe.
Reader's Guide
The Rosetta mission, launched on 2 March 2004, rendezvoused with Churyumov–Gerasimenko on 6 August 2014 and entered orbit on 10 September 2014. Its lander, Philae, landed on the comet's surface on 12 November 2014, becoming the first spacecraft to land on a comet nucleus. The Rosetta spacecraft ended its mission by landing on the comet in its Maʽat region on 30 September 2016. During Rosetta's lifetime, many surface changes were observed near perihelion, including evolving circular patterns in smooth terrains, a growing fracture in the neck region, displaced boulders, and collapsing cliffs. One notable cliff collapse in December 2015 was captured as a bright patch of light, the first landslide on a comet associated with an outburst. The comet's 2021 apparition marked its closest approach to Earth since 1982, reaching apparent magnitude 9 and visible with amateur telescopes. Two outbursts were observed during that apparition, on 29 October and 17 November 2021. The comet most recently came to perihelion on 2 November 2021 and will next come to perihelion on 9 April 2028.
Did You Know?
- The comet's two-lobe shape is a contact binary formed by a gentle, low-velocity collision of two objects.
- The largest boulder on the comet, Cheops, measures up to 45 meters and is named for the pyramid in Giza.
- The comet's rotational period decreased from 12.76 hours to 12.4 hours during its 2009 perihelion passage.
More in Named Comets, Part 6 1-24
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