Comet Encke
Shortest-period bright comet, named after its orbit calculator.
Comet Encke (official designation 2P/Encke) is a periodic comet that completes an orbit of the Sun once every 3.3 years, the shortest period of any reasonably bright comet. It was first recorded by Pierre Méchain on 17 January 1786, but was not recognized as a periodic comet until 1819, when its orbit was calculated by Johann Franz Encke. Like Halley's Comet, it is named after the calculator of its orbit rather than its discoverer. Its nucleus has a diameter of 4.86 km and a very low albedo, reflecting only 4.6% of the light it receives, though it becomes much more visible near perihelion due to its coma and tail.
Quick Facts
- Pronounced
- ' · E · N · k · i
- Discoverer
- Pierre Méchain · Johann Franz Encke · (recognition of periodicity)
- Discovery Date
- 17 January 1786
- Mpc Name
- P/1786 B1, P/1795 V1 · P/1805 U1, P/1818 W1 · P/1822 L1
- Designations
- 1786 I, 1795, 1805 · 1819 I, 1822 II, 1825 III · 1829, 1832 I, 1835 II · 1838, 1842 I, 1845 IV
- Orbit Ref
- jpldata · MPC
- Epoch
- 5 May 2025 (JD 2460800.5)
- Obs
- 6,124
- Perihelion
- 0.339 AU
- Aphelion
- 4.097 AU
- Semimajor
- 2.218 AU
- Eccentricity
- 0.84711
Facts from the source article.
Lore & Background
Encke's Comet was independently observed by several astronomers: Pierre Méchain and Charles Messier in 1786, Caroline Herschel in 1795, and Jean-Louis Pons in 1818. Johann Franz Encke linked observations from 1786, 1795, 1805, and 1818 to the same object, publishing his conclusions in 1819 and correctly predicting its return in 1822, when it was recovered by Carl Ludwig Christian Rümker. Encke himself insisted the comet be called Pons's Comet, but this was not widely adopted. Its orbit is unstable due to perturbations and outgassing; it is currently near a 7:2 mean motion resonance with Jupiter. Its minimum orbit intersection distance with Earth is 0.167 AU, and close approaches to Earth occur roughly every 33 years. The comet has been observed at every perihelion since 1818 except 1944. In 1980, it became the first comet detected by radar, at Arecibo Observatory. On 20 April 2007, STEREO-A observed its tail temporarily torn off by a coronal mass ejection.
Reader's Guide
Comet Encke holds significance as the first periodic comet discovered after Halley's Comet and as the comet with the shortest orbital period among reasonably bright comets. Its orbit, frequently perturbed by inner planets, has been studied extensively since the 19th century. The comet is believed to be the originator of the Taurid meteor showers (Northern and Southern Taurids in November, Beta Taurids in June–July), and the near-Earth asteroid 2004 TG10 is likely an inactive fragment that broke off about 4,000–4,500 years ago. Measurements from NASA's MESSENGER spacecraft suggest Encke may contribute to seasonal meteor showers on Mercury, causing periodic spikes in calcium in the planet's atmosphere. The Tunguska event of 1908 has been hypothesized as possibly caused by a fragment of Comet Encke. Additionally, the comet has been linked to theories about the ancient swastika symbol, with some suggesting its appearance from head-on, with curved jets, could have inspired the motif. Encke also played a role in the scientific history of luminiferous aether. Several proposed missions to Encke, including NASA's CONTOUR mission (which failed in 2002) and earlier NASA and German DLR proposals, were never successfully carried out.
Did You Know?
- Encke's Comet has the shortest orbital period (3.3 years) of any reasonably bright comet.
- It was the first comet detected by radar, in 1980 at Arecibo Observatory.
- On 20 April 2007, STEREO-A observed the comet's tail temporarily torn off by a coronal mass ejection.
More in Named Comets, Part 5 1-24
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