162P/Siding Spring

For other comets discovered by the Siding Spring Observatory, see Comet Siding Spring (disambiguation).

162P/Siding Spring is a Jupiter-family comet with an orbital period of 5.3 years. It was discovered in images obtained on 10 October 2004 as part of the Siding Spring Survey.^[1]

162P/Siding Spring

The comet on 12 November 2004, displaying a narrow tail
Discovery[1]
Discovered by	Siding Spring Observatory
Discovery date	October 10, 2004
Designations
Alternative designations	P/2004 TU12
Orbital characteristics[2]
Epoch	27 October 2010
Aphelion	4.873 AU
Perihelion	1.233 AU
Semi-major axis	3.053 AU
Eccentricity	0.5961
Orbital period	5.33 years
Inclination	27.817°
Last perihelion	7 December 2020
Next perihelion	17 May 2026
TJupiter	2.792
Earth MOID	0.239 AU
Physical characteristics
Dimensions	14.06 ± 0.96 km[3]
Sidereal rotation period	32.86 hours[4]
Geometric albedo	0.022 ± 0.003[4]
Comet total magnitude (M1)	15.2

The comet was discovered during the Siding Spring Survey as an asteroidal object shining with an apparent magnitude of 14.1 but a tail extending for about 4 arcminutes was observed on 12 November 2004, indicating that it is a comet.^[1] The tail grew longer the next days, reaching a length of over 10 arcminutes on 15 November. Two days later the tail was fainter, and barely visible within one arcminute from the nucleus.^[5] On 21 October 2031 the comet will approach Earth at a distance of 0.2456 AU (36.74 million km).^[2]

The comet was observed by NASA Infrared Telescope Facility in 2004, finding that the nucleus has an effective radius of 6.0 ± 0.8 km, which corresponds to a visual albedo of 0.034 ± 0.014,^[6] and a reflectance spectrum typical of a D-type asteroid.^[7] Further observations by the Spitzer Space Telescope indicate an effective radius of 7.03 ± 0.48 km.^[3] This is one of the largest nuclei of Jupiter family comets with known radius.^[6] More detailed observations indicate that the nucleus has axis ratios a/b = 1.56 and b/c = 2.33, and could possibly have two lobes.^[4] The sidereal period of the comet is 32.864 ± 0.001 hours.^[4]

See also

• 107P/Wilson-Harrington and 133P/Elst-Pizarro - comets with similar intermittent activity