123P/West–Hartley

Periodic comet From Wikipedia, the free encyclopedia

Comet West–Hartley is a periodic comet roughly 4 km in diameter with a 7.67-year orbit around the Sun. The current orbit does not bring it closer than about 1.2 AU (180 million km) from Earth.[2] It will next come to perihelion on 21 September 2026, when the comet will have a solar elongation of 22 degrees.[5]

DiscoveredbyRichard M. West
Malcolm Hartley
DiscoverysiteEuropean Southern Observatory
Discoverydate11 May 1989
P/1989 E3, P/1995 S2
Quick facts Discovery, Discovered by ...
123P/West–Hartley
Discovery image of Comet West–Hartley taken from ESO on 11 May 1989.[1]
Discovery
Discovered byRichard M. West
Malcolm Hartley
Discovery siteEuropean Southern Observatory
Discovery date11 May 1989
Designations
P/1989 E3, P/1995 S2
1988 XVI, 1989k
Orbital characteristics[2][3]
Epoch7 October 2026
(JD 2461320.5)
Observation arc30.39 years
Number of
observations		4,399
Aphelion5.616 AU
Perihelion2.159 AU
Semi-major axis3.887 AU
Eccentricity0.44469
Orbital period7.665 years
Inclination15.281°
45.848°
Argument of
periapsis		103.88°
Mean anomaly1.945°
Last perihelion5 February 2019[4]
Next perihelion21 September 2026[4][5]
TJupiter2.832
Earth MOID1.197 AU
Jupiter MOID0.704 AU
Physical characteristics[2][6][7]
Mean radius
2.18±0.23 km
3.7 hours
Comet total
magnitude (M1)		8.2
Comet nuclear
magnitude (M2)		13.8
17.5
(2026-04-03)[8]
Close

Physical characteristics

The first attempts to measure the effective radius of its nucleus in 2000 were not successful due to too much scatter data in light curves obtained to provide reliable estimates.[9] Recent attempts to measure the comet's light curves between 2004 and 2015 revealed that the nucleus is about 2.18 km (1.35 mi) in radius, rotating once every 3.7 hours.[6]

References

External links

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