1991 VG

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1991 VG
Discovered by Steward Observatory (691)
Discovery date November 6, 1991
MPC 28316
Apollo Apollo
Orbital characteristics[2]
Epoch 2014-12-09
Uncertainty parameter 2
Observation arc 173
Aphelion 1.0774357 AU
Perihelion 0.97649061 AU
1.0269631 AU
Eccentricity 0.0491473
380.12874 d
1.04 y
Inclination 1.445420°
Earth MOID 0.0041420 AU
Physical characteristics
Dimensions 5–12 m (15–40 ft)[3]


Earth-like orbit[edit]

On November 6, 1991, Scotti discovered a faint object which was designated 1991 VG soon after discovery.[4] The object's heliocentric orbit was found to be very similar to Earth's orbit[5] and it was found that it would make a close approach to Earth just a month after discovery (on December 5, 1991[2]). Given such an Earth-like orbit, the dynamical lifetime of such an object is relatively short with the object quickly either impacting Earth or being perturbed by Earth onto a different orbit. The similarity of its orbit with Earth was also very difficult to explain from natural sources, with ejecta from a recent Lunar impact or non-gravitational perturbations such as the Yarkovsky effect having been suggested.[6] More recently, the first Earth Trojan asteroid - 2010 TK7 has been identified and such objects could well be a source for objects like 1991 VG.

Possible monolithic structure[edit]

Since the discovery of 1991 VG, about 80% of small asteroids with absolute magnitudes (H) fainter than 22.0 (corresponding to sizes smaller than about 200 meters) which have had their lightcurve measured have rotation periods under 2 hours. Such rapid rotation rates are typically associated with asteroids that are monolithic bodies or welded conglomerates having sufficient intrinsic strength to counteraact centrifugal forces. More slowly rotating asteroids are sometimes gravitationally bound aggregates.[7]

Possible artificial origin[edit]



  1. ^ "1991 VG". Minor Planet Center. 27 April 1992. 
  2. ^ a b c "JPL Small-Body Database Browser: (1991 VG)" (last observation: 1992-04-27; arc: 173 days). Jet Propulsion Laboratory. Retrieved 2015-06-04. 
  4. ^ satobs.org: James Scotti, Re: What is 1991 VG?
  5. ^ jpl.nasa.gov, 1991 VG Earth Impact Risk Summary

External links[edit]