Comet Encke

2P/Encke
	Comet Encke photographed from the Kitt Peak Observatory on 5 January 1994.
Discovery
Discovered by	Pierre Méchain; Johann Franz Encke; (recognition of periodicity);
Discovery date	17 January 1786
Designations
MPC designation	P/1786 B1, P/1795 V1; P/1805 U1, P/1818 W1; P/1822 L1;
Pronunciation	/ˈɛŋki/
Alternative designations	1786 I, 1795, 1805; 1819 I, 1822 II, 1825 III; 1829, 1832 I, 1835 II; 1838, 1842 I, 1845 IV;
Orbital characteristics
Epoch	5 May 2025 (JD 2460800.5)
Observation arc	240.60 years
Number of; observations	6,124
Aphelion	4.097 AU
Perihelion	0.339 AU
Semi-major axis	2.218 AU
Eccentricity	0.84711
Orbital period	3.304 years
Max. orbital speed	69.5 km/s (250,000 km/h)
Inclination	11.344°
Longitude of; ascending node	334.01°
Argument of; periapsis	187.28°
Mean anomaly	167.19°
Last perihelion	22 October 2023
Next perihelion	10 February 2027
TJupiter	3.023
Earth MOID	0.167 AU (25.0 million km)
Jupiter MOID	0.909 AU (136.0 million km)
Physical characteristics
Mean diameter	4.86 km (3.02 mi)
Synodic rotation period	11.083±0.003 hours
Geometric albedo	0.046
Spectral type	(V–R) = 0.44±0.06
Comet total; magnitude (M1)	15.6

Comet Encke /ˈɛŋki/, or Encke's Comet (official designation: 2P/Encke), is a periodic comet that completes an orbit of the Sun once every 3.3 years. (This is the shortest period of a reasonably bright comet; the faint main-belt comet 311P/PanSTARRS has a period of 3.2 years.) Encke was first recorded by Pierre Méchain on 17 January 1786, but it was not recognized as a periodic comet until 1819 when its orbit was computed by Johann Franz Encke. Like Halley's Comet, it is unusual in its being named after the calculator of its orbit rather than its discoverer. Like most comets, it has a very low albedo, reflecting only 4.6% of the light its nucleus receives, although comets generate a large coma and tail that can make them much more visible during their perihelion (closest approach to the Sun). The diameter of the nucleus of Encke's Comet is 4.86 km (3.02 mi).

It reaches opposition on 8 October 2026 when it will be about magnitude 15. It comes to perihelion on 10 February 2027 when it will have a solar elongation of 10 degrees.