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Encyclopedia > Asteroids V

ASTEROIDS : THE TROJANS

 The Trojan asteroids are on the same orbit as Jupiter; they are either ahead of 60° on Jupiter (point L4) or delayed by 60 ° (point L5). These two points, named Lagrangian points correspond to areas of stability for objects on the same orbit as Jupiter.

Other planets also have Trojan asteroids on their orbit: Mars, Uranus, Neptune but also the Earth. Its "Trojans" are difficult to observe: we saw one at the point L4, 2010 TK7 having a size of 320 meters.


Some Jupiter Trojans

Some Jupiter Trojans ordered from the larger until the more recently discovered 

Number Name Size 
en km
 Distance from Sun 
en UA
 Eccentricity   Inclination   Lagrangian 
 point 
 Date of  
 discovery
588 Achille 100 4.41/5.95 0.149 10°  L4 1906
617 Patroclus 110 4.50/5.95 0.139 22°  L5 1906
624 Hector 140 5.10/5.33 0.023 18°  L4 1907
659 Nestor 70 4.62/5.81 0.113  L4 1908
884 Priam 75 4.53/5.79 0.122  L5 1917
911 Agamemnon 176 4.88/5.59 0.068 22°  L4 1919
1143 Odyssey 115 4.77/5.74 0.092  L4 1930
   ...            
- 2005 YB143 5 4.75/5.94 0.112 17°  L5 2005
- 2005 MU3 7 4.99/5.38 0.038 15°  L4 2005

There are 7284 Trojan asteroids of Jupiter suspected, observed until the present date (December 10, 2019), of which 4914 are numbered (that is to say confirmed). Curiously, they are not equally divided between those who are "ahead" and those "late". There are about two times more numerous in advance (at point L4) than late (at point L5). Also note that they remain at a constant distance of Jupiter, with an eccentricity and an inclination of their orbits much larger than those of Jupiter. 

 

Trojans of Mars

Some Trojan asteroids of Mars are doubtful: it will be necessary to follow their orbits for several revolutions to be sure they are really at the Lagrangian points.

Number Name Size 
in km
 Distance from the Sun 
in AU
 Eccentricity   Inclination   Lagrangian 
 point 
 Date of  
 discovery
5261 Eureka 3 1.42/1.62 0.065 20°  L5 1990
101429 1998 VF31 1.5 1.37/1.67 0.101 31°  L5 1998
121514 1999 UJ7 2.0 1.46/1.58 0.039 17°  L4 1999
311999 2007 NS2 1.0 1.44/1.61 0.054 19°  L5 2007
- 2001 DH47 1.0 1.44/1.61 0.054 19°  L5 2001
- 2011 SC191 1.0 1.44/1.61 0.054 19°  L5 2011
- 2011 SL25 1.0 1.44/1.61 0.054 19°  L5 2011
- 2011 UN63 1.0 1.44/1.61 0.054 19°  L5 2011
 

The case of the Earth

We only know one asteroid which seems to be a Trojan Earth.

Number Name Size 
in km
 Distance from Sun 
en UA
 Eccentricity   Inclination   Lagrangian 
 point 
 Date of  
 discovery
- 2010 TK7 0.4 0.81/1.19 0.191 20.9°  L5 1990
 

The Troyan of Uranus

We only know one asteroid which seems to be a Trojan of Uranus.

Number Name Size 
in km
 Distance to the Sun 
in AU
 Eccentricity   Inclination   Lagrange 
 point 
 Date of  
 discovery
- 2011 QF 99 50 15/22 0,178 10.8°  L4 2011
 

Trojans of Neptune

We known 20 possible Neptune Trojans at point L4 and 3 at point L5, but their great distance from Earth makes their observation difficult and the orbital parameters remain uncertain. Below, nine of them.

Number Name Size 
in km
 Distance from Sun 
in AU
 Eccentricity   Inclination   Lagrangian 
 point 
 Date of  
 discovery
- 2001 QR322 80 29.3/31.1 0.029 1.3°  L4 2001
- 2004 KV18 60 24.5/35.7 0.185 13.6°  L5 2004
- 2004 UP10 (385571) Otrera 42 29.3/30.9 0.025 1.4°  L4 2004
- 2005 TN53 40 28.2/31.9 0.062 25.0°  L4 2005
- 2005 TO74 (385695) 50 28.5/31.6 0.051 5.3°  L4 2005
- 2006 RJ103  140 29.1/30.8 0.028 8.2°  L4 2006
- 2007 VL305  60 28.1/32.0 0.064 28.1°  L4 2007
- 2008 LC18  55 27.5/32.5 0.083 27.6°  L5 2008
- 2011 HM102  140 27.7/32.4 0.078 29.4°  L5 2011