1995 GJ


1995 GJ
Discovered byD. Jewitt
J. Chen
Discovery siteMauna Kea Obs.
Discovery date3 April 1995
(first observed only)
1995 GJ
TNO[2] · distant[1]
cubewano (hot)[4]
Orbital characteristics[2]
Epoch 4 April 1995 (JD 2449811.5)
Uncertainty parameter 9[2] · E[1]
Observation arc1 days
Aphelion47±42126 AU
Perihelion39±1920 AU
43±38618 AU
Physical characteristics
Mean diameter
170 km (est. at 0.10)[5]
176 km (est. at 0.09)[4]
179 km (est. at 0.08)[6]

1995 GJ might be a trans-Neptunian object and/or high-inclination cubewano from the Kuiper belt in the outermost region of the Solar System, and based on the calculated distance and brightness is assumed to be approximately 175 kilometers (110 miles) in diameter. It is a lost minor planet that has only been observed six times on the nights of 3–4 April 1995, by David Jewitt and Jun Chen at the Mauna Kea Observatory, Hawaii, using the UH88 telescope, and has not been observed ever since.[1][3] The object is estimated to have been discovered right at perihelion (closest approach to the Sun) at a distance of 39±1900 AU from the Sun.[2] On the night of discovery, the object is estimated to have been moving away from Earth at 16 km/s with the uncertainty in the velocity being an unrealistic ±238000 km/s (80% the speed of light).


The nominal orbit of 1995 GJ suggests it orbits the Sun at a distance of 39–46 AU once every 281 years with an assumed eccentricity of 0.09 and an inclination of 23° with respect to the ecliptic. But 1995 GJ has the highest possible orbital uncertainty and thus very large uncertainties in the orbital elements.[2] With only a 1-day observation arc, the orbit is so poorly constrained as to be almost worthless. The eccentricity is listed as 0.09 ± 771,[2] even though realistically it will be less than 1.

Otherwise known for their low inclinations, this cubewano may be the first of its kind to have an inclination greater than 20°.[4] But as a one-night stand with only 6 observations,[2] 1995 GJ has numerous orbits that fit the uncertainties in the very small dataset. 1995 GJ could be a trans-Neptunian object, a centaur, or a much closer main belt asteroid 100 times smaller in diameter. As an example, (392741) 2012 SQ31 (when it had a one-day observation arc) was thought to be a potential trans-Neptunian dwarf planet, but is now known to be a small main belt asteroid.

Using the nominal orbit with the assumed eccentricity,[3] 1995 GJ may come to opposition around mid March of each year at an apparent magnitude of 22.9.

As of 2018, the uncertainty in the object's distance from the Sun is an unrealistic ±160 trillion km (17 ly).[7]

Date Uncertainty in
distance from the Sun
1995-Apr ±730 billion km
1995-May ±1 trillion km
1996-Jul ±10 trillion km
2009-Jan ±100 trillion km
2026-Feb ±200 trillion km


  1. ^ a b c d e "1995 GJ". Minor Planet Center. Archived from the original on 18 February 2018. Retrieved 2 March 2020.CS1 maint: bot: original URL status unknown (link)()
  2. ^ a b c d e f g h i "JPL Small-Body Database Browser: (1995 GJ)" (1995-04-04 last obs.). Jet Propulsion Laboratory. Retrieved 2 March 2020. ([1] per 14 July 2012)
  3. ^ a b c "MPEC 1995-G07: 1995 GJ". Minor Planet Center. 7 April 1995. Retrieved 3 August 2017.
  4. ^ a b c "List of Known Trans-Neptunian Objects". Johnston's Archive. 18 August 2020. Retrieved 8 September 2020.
  5. ^ "Asteroid Size Estimator". CNEOS/JPL. Retrieved 2 March 2020.
  6. ^ "How many dwarf planets are there in the outer solar system?". Mike Brown. Retrieved 2 March 2020.
  7. ^ JPL Horizons: 1995 GJ (Soln.date: 2014-Feb-04)
    Observer Location: @sun
    Under "Table Settings" select "39. Range & range-rate". Uncertainty in distance (km) is RNG_3sigma

External links

  • List Of Transneptunian Objects, Minor Planet Center
  • 1995 GJ at the JPL Small-Body Database
    • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters