10P/Tempel

Comet Tempel 2 photographed by H. M. Jeffers from theLick Observatory in 1946[1]
Discovery
Discovered by	Wilhelm Tempel
Discovery date	4 July 1873
Designations
MPC designation	P/1873 N1, P/1878 O1
Alternative designations	Tempel 2 1873 II, 1878 III, 1894 III 1899 IV, 1904 III, 1915 I 1920 II, 1925 IV, 1930 VII 1946 III, 1951 VIII, 1957 II 1962 VI, 1967 X, 1972 X 1978 V, 1983 X, 1988 XIV 1994 VII
Orbital characteristics[4][5]
Epoch	5 May 2025 (JD 2460800.5)
Observation arc	130.78 years
Number of observations	5,700
Aphelion	4.710 AU
Perihelion	1.417 AU
Semi-major axis	3.064 AU
Eccentricity	0.53738
Orbital period	5.362 years
Inclination	12.027°
Longitude of ascending node	117.80°
Argument of periapsis	195.50°
Mean anomaly	276.53°
Last perihelion	24 March 2021
Next perihelion	2 August 2026[2][3]
TJupiter	2.965
EarthMOID	0.410 AU
JupiterMOID	0.622 AU
Physical characteristics
Mean diameter	10.6 km (6.6 mi)[6]
Synodic rotation period	8.948±0.001 hours[7]
Geometric albedo	0.022[8]
Spectral type	(V–R) =0.561±0.04[9]
Comet total magnitude (M1)	14.3

10P/Tempel, also known asTempel 2, is aperiodicJupiter-familycomet with a 5-year orbital period. It was discovered on 4 July 1873 byWilhelm Tempel.^[10] At theperihelion passage on 2 August 2026 thesolar elongation is calculated at 164 degrees, withapparent magnitude approximately 8,^[2] with closest approach to Earth on 3 August 2026 at a distance of 0.414 AU (61.9 million km).^[4]

Thecomet nucleus is estimated to be roughly the size ofHalley's Comet at 10.6 km (6.6 mi) in diameter with a lowalbedo of 0.022.^[8] The nucleus is dark becausehydrocarbons on the surface have been converted to a dark, tar like substance by solarultraviolet radiation. The nucleus is large enough that even nearaphelion (furthest distance from the Sun which is near the orbit ofJupiter) the comet remains brighter than about magnitude 21.

During the 2010 apparition the comet brightened to aboutapparent magnitude 8.^[2] The most favorable apparition of 10P/Tempel 2 was in 1925 when it came within 0.35 AU (52 million km; 33 million mi) of Earth with anapparent magnitude of 6.5.^[10][11]

Infrared spectroscopy conducted in July 2010 revealed the presence ofCH
₃OH,C
₂H
₆,NH
₃ andHCN in trace amounts within its coma, with their peak intensities suggesting a possible existence of a distributed source that was released from the nucleus as sublimed icy grains.^[12]

TheJet Propulsion Laboratory proposed a flyby of the comet with a flight spare ofMariner 4.^[13] The probe was instead used for aVenus flyby asMariner 5.^[13]

10P/Tempel was to be the target of the NASA part of theInternational Comet Mission after transporting a European probe to a flyby of Halley's Comet.^[14] The plan was to use Solar electric propulsion to get the craft to orbit the comet.^[15] The program was cancelled in November 1979.^[15]

• 10P/Tempel at theJPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters
• Elements and Ephemeris for 10P/Tempel –Minor Planet Center
• 10P/Tempel 2 /2010 – Seiichi Yoshida @ aerith.net
• 10P/Tempel 2 (2010) (astrosurf)

• Periodic comets
• Numbered comets
• Comets in 2015
• Comets in 2021
• Astronomical objects discovered in 1873
• Discoveries by Wilhelm Tempel

• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from July 2025
• JPL Small-Body Database ID same as Wikidata