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P/2005 U1
Discovery date 2005 October 24
Main-belt comet[1][2]
Orbital characteristics[3]
Epoch January 7, 2006
T_jup = 3.153
Aphelion 3.9645 AU (Q)
Perihelion 2.3647 AU (q)
3.1646 AU (a)
Eccentricity 0.25277
5.63 yr
28.566° (M)
Inclination 1.2662°
Physical characteristics
Dimensions ~0.6 km[4]
Mean density
1.0(?) g/cm³ (assumed)[4]
Albedo 0.04 (assumed)[4]
Surface temp. min mean max
Kelvin[4] 142 K 159 K 184 K
19.62 to 23.41
20.1 ± 0.4R[4]

238P/Read (P/2005 U1) is a main-belt comet[1][2] discovered on 2005 October 24 by M. T. Read using the Spacewatch 36 inch telescope on Kitt Peak. It has an orbit within the asteroid belt and has displayed the coma of a traditional comet. It fits the definition of an Encke-type comet with (TJupiter > 3; a < aJupiter).[3]

Before it was discovered 238P came to perihelion on 2005 July 27.[3] When it was discovered on 2005 October 24, it showed vigorous cometary activity until 2005 December 27.[4] Outgassing likely began at least 2 months before discovery.[4] The activity of 238P is much stronger than 133P/Elst-Pizarro and 176P/LINEAR.[4] This may indicate that the impact assumed to have triggered 238P's activity occurred very recently.[4]

Observations of 238P when it was inactive in 2007 suggests that it has a small nucleus only about 0.6 km in diameter.[4]

It last came to perihelion on 2011 March 10,[4] and will next come to perihelion on 2016 October 22.[5][6]


  1. ^ a b Henry H. Hsieh (May 2010). "Main Belt Comets". Hawaii. Retrieved 2010-12-15.  (older 2010 site) Archived August 10, 2009, at the Wayback Machine.
  2. ^ a b David Jewitt. "Main Belt Comets". UCLA, Department of Earth and Space Sciences. Retrieved 2010-12-15. 
  3. ^ a b c "JPL Small-Body Database Browser: 238P/Read (2005 U1)" (last observation: 2011-09-14). Archived from the original on 2012-08-09. Retrieved 2012-08-08.  from the original on 2012-08-08
  4. ^ a b c d e f g h i j k Hsieh, Henry H.; Jewitt; David C.; Ishiguro, Masateru (2009). "Physical Properties of Main-Belt Comet P/2005 U1 (Read)". The Astronomical Journal. 137 (1): 157–168. arXiv:0810.1351Freely accessible. Bibcode:2009AJ....137..157H. doi:10.1088/0004-6256/137/1/157. Retrieved 2010-12-18. 
  5. ^ Syuichi Nakano (2010-08-20). "P/Read (2005 U1 = 2010 N2)". OAA Computing and Minor Planet Sections. Retrieved 2011-07-25. 
  6. ^ "238P/Read Orbit". Minor Planet Center. Retrieved 2014-06-20. 

External links[edit]

Numbered comets
238P/Read Next