Neptune Trojan

A Neptune Trojan is an asteroid which is in the same orbit as the planet Neptune.

Their name comes from the Trojan asteroids which have the same orbital period as a planet. As of March 2007, there are six[1][2] known Neptune Trojans. They lie in the elongated, curved region around the L4 Lagrangian point 60° ahead of Neptune. The six Neptune Trojans are 2001 QR322, 2004 UP10, 2005 TN53, 2005 TO74, 2006 RJ103 and 2007 RW10.

The discovery of 2005 TN53 in a high inclination (>25°) orbit is significant because it suggests a ‘thick’ cloud of Trojans.[3] It is believed that large (radius ≈ 100 km) Neptune Trojans could greatly outnumber the Jupiter Trojans.[4][5]

If any other L5 Neptune Trojans are discovered in the near future, it may be possible for the New Horizons spacecraft to investigate them as it passes through the region in 2014 while on its way to Pluto.


  1. 2005 TN74, listed earlier as a Neptune Trojan, proved to be a scattered disk object.
  2. List Of Neptune Trojans (March 8, 2007) at
  3. S. Sheppard and C. Trujillo "A Thick Cloud of Neptune Trojans and Their Colors" (2006) Science 313, pp. 511-514
  4. E. I. Chiang and Y. Lithwick Neptune Trojans as a Testbed for Planet Formation, The Astrophysical Journal, 628, pp. 520–532 Preprint
  5. popular article (Jan 2007)