Encke's Comet
| 2P / Encke [i] | |
|---|---|
|
|
| Properties of the orbit ( animation ) | |
| Orbit type | short-term |
| Numerical eccentricity | 0.847 |
| Perihelion | 0.339 AU |
| Aphelion | 4,097 AU |
| Major semi-axis | 2.218 AU |
| Sidereal period | 3 a 110 d |
| Inclination of the orbit plane | 11.8 ° |
| Perihelion | last: March 10, 2017 next: June 25, 2020 |
| Orbital velocity in the perihelion | 69.53 km / s |
| Physical properties of the core | |
| Medium diameter | 4.8 km |
| Albedo | 0.047 |
| history | |
| Explorer | Jean-Louis Pons |
| Date of discovery | November 27, 1818 |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
The Encke Comet (official name 2P / Encke ) is a short-period comet named after Johann Franz Encke . It has one of the shortest orbital times of any known comet .
Encke was not the discoverer of the comet, but through extensive studies and orbital calculations , he succeeded in connecting different sightings in the years 1786, 1795, 1805 and 1818. He published his results in Correspondance Astronomique in 1819 and correctly predicted the return for 1822.
history
Its official name means that it is the second comet after Halley's Comet (1P / Halley) to be recognized as periodically recurring. The comet was first discovered by Pierre Méchain on January 17, 1786 . When he returned in 1795, it was found by Caroline Herschel , in 1805 by Jean-Louis Pons and again in 1818 by Pons, before Encke could assign the four cometary phenomena to a single object. While comets are usually named after their discoverer , in this case the comet was named after the person who calculated its orbit, so that the comet is now called 2P / Encke. The Encke Comet was one of the planned mission targets of the failed comet probe CONTOUR .
Orbit
Encke's comet runs in an elongated elliptical orbit around the sun , the point closest to the sun ( perihelion ) with 0.339 AU in the area of the orbit of the planet Mercury , while the point furthest from the sun ( aphelion ) with 4.097 AU extends into the area of Jupiter's orbit . The inclination of its orbit against the ecliptic is 11.8 °. With an orbital period of only 3.3 years, Encke's Comet has the shortest orbital period of all known periodic comets.
_1.380_(P_XIII)_Appearance_of_Encke%27s_Comet.jpg)
As early as the 19th century it was found that the orbital period of Encke's comet was constantly shortened slightly, which was regarded as evidence of the existence of the ether , the frictional resistance of which was held responsible for the deceleration. Today we know that the deceleration is due to the fact that matter is ejected from the comet's core in the form of jets near the sun , and these have a decelerating effect. The constant loss of matter also leads to a decrease in the brightness of the comet: The absolute brightness of the comet Encke decreases on average by around 0.5 size classes in 50 years . Its diameter is therefore only estimated to be around 4.8 km.
Meteors
The meteor shower of the Taurids goes back to the Encke comet . Some scientists blame a fragment of what used to be the larger comet for destruction during the Bronze Age in the Fertile Crescent . A suspected impact crater called Umm al-Binni in southern Iraq is considered possible evidence, but a detailed geological study of this structure is still pending.
See also
Web links
- Gary W. Kronk's Cometography - 2P / Encke (English)
- Comets and the Bronze Age Collapse (English)
- Comet Encke in Tibet
Individual evidence
- ↑ a b Encke's Comet in the Small-Body Database of the Jet Propulsion Laboratory (English).
- ↑ 2P / Encke past, present and future orbits by Kazuo Kinoshita