162P/Siding Spring

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

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]
Discovery site	Siding Spring Observatory
Discovery date	10 October 2004
Designations
Alternative designations	P/2004 TU12
Orbital characteristics[2][3]
Epoch	5 May 2025 (JD 2460800.5)
Observation arc	35.27 years
Earliest precovery date	23 March 1990
Number of observations	3,273
Aphelion	4.894 AU
Perihelion	1.289 AU
Semi-major axis	3.092 AU
Eccentricity	0.58295
Orbital period	5.33 years
Inclination	27.554°
Longitude of ascending node	30.878°
Argument of periapsis	357.24°
Mean anomaly	291.51°
Last perihelion	7 December 2020
Next perihelion	17 May 2026
TJupiter	2.792
Earth MOID	0.239 AU
Jupiter MOID	0.587 AU
Physical characteristics
Mean diameter	14.06±0.96 km[4]
Sidereal rotation period	32.864±0.001 hours[5]
Geometric albedo	0.022±0.003[5]
Spectral type	(V–R) = 0.45±0.01[6]
Comet total magnitude (M1)	15.2

Observational history

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.^[7] On 21 October 2031, the comet will approach Earth at a distance of 0.2456 AU (36.74 million km).^[2]

Physical characteristics

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,^[8] and a reflectance spectrum typical of a D-type asteroid.^[9] Further observations by the Spitzer Space Telescope indicate an effective radius of 7.03 ± 0.48 km.^[4] This is one of the largest nuclei of Jupiter family comets with known radius.^[8] 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.^[5] The sidereal period of the comet is 32.864±0.001 hours.^[5]

See also

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