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Discovery [1] [2] | |
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Discovered by | New Horizons KBO Search |
Discovery site | Las Campanas Obs. |
Discovery date | 18 April 2012 (first observed only) |
Designations | |
2012 HE85 | |
VNH0021 [3] | |
Orbital characteristics [4] | |
Epoch 27 April 2019 (JD 2458600.5) | |
Uncertainty parameter 3 [1] | |
Observation arc | 5.18 yr (1,892 d) |
Aphelion | 49.639 AU |
Perihelion | 40.156 AU |
44.897 AU | |
Eccentricity | 0.1056 |
300.84 yr (109,882 d) | |
12.220° | |
0° 0m 11.88s / day | |
Inclination | 3.0161° |
234.99° | |
37.770° | |
Physical characteristics | |
8.9 [1] [4] | |
2012 HE85 is a small, resonant trans-Neptunian object from the Kuiper belt, located in the outermost region of the Solar System, approximately 74 kilometers (46 miles) in diameter. It was first observed by a team of astronomers using one of the Magellan Telescopes in Chile during the New Horizons KBO Search on 18 April 2012, in order to find a potential flyby target for the New Horizons spacecraft. [1] The likely 5:9 resonant object was imaged by the spacecraft from afar at a record distance from Earth in 2017. [7]
The Kuiper belt object is considered to be a resonant trans-Neptunian object in a higher 5:9 orbital resonance with the ice giant Neptune. [5] [6] It orbits the Sun at a distance of 40.2–49.6 AU once every 300 years and 10 months (semi-major axis of 44.9 AU). Its orbit has an eccentricity of 0.11 and an inclination of 3° with respect to the ecliptic. [4] The body's observation arc begins with its official first observation by David Osip, Paul Schechter, David Borncamp, Susan Benecchi and Scott Sheppard of the New Horizons KBO Search ( 268 ) using the Magellan II (Clay) telescope at the Las Campanas Observatory, located in the Atacama desert in Chile. [1] [2]
When the New Horizons spacecraft imaged 2012 HE85 in 2017, it was the farthest from Earth ever captured by a spacecraft. The image was taken by the spacecraft's Long Range Reconnaissance Imager (LORRI) on 5 December 2017 at more than 6.12 billion kilometers (40.9 AU) away from Earth. This record was previously held by the Voyager 1 spacecraft which took the iconic Pale Blue Dot image at 6.06 billion kilometers from Earth in February 1990. [7]
In December 2017, New Horizons also imaged the classical Kuiper belt object (516977) 2012 HZ84 , which was discovered by the same team of astronomers the night before they first observed 2012 HE85. [7] Both objects held this record for little more than one year, until it was superseded on New Year's Eve 2018/19, when New Horizons made its close flyby on 486958 Arrokoth at a new record distance of 6.4 billion kilometers from Earth. [8]
According to Johnston's Archive, the object measures 74 kilometers in diameter based on an assumed albedo of 0.09 and an absolute magnitude of 8.9. [4] [5] Another estimates gives a smaller diameter of 31 kilometers due to an assumed albedo of 0.15. [3] As of 2019, no rotational lightcurve of 2012 HE85 has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown. [4]
As of 2025, this minor planet has neither been numbered nor named by the Minor Planet Center. [1]