Discovery | |
---|---|
Discovered by | Pan-STARRS 1 (F51) |
Discovery date | 15 March 2015 |
Orbital characteristics | |
Epoch | 7 May 2017 (JD 2457880.5) |
Observation arc | 1.96 yr |
Aphelion | |
Perihelion | 1.0421 AU |
Semi-major axis | |
Eccentricity | 0.99730 |
Orbital period |
|
Inclination | 6.3490° |
235.21° | |
Argument of periapsis | 68.197° |
Earth MOID | 0.1016 AU [2] [3] |
Mars MOID | <0.00005 AU [3] |
Jupiter MOID | 0.0794 AU [2] [3] |
Saturn MOID | 0.2869 AU [3] |
Physical characteristics [4] | |
Dimensions | 2.6–2.8 km (1.6–1.7 mi) |
Mean diameter | 2.75 km (1.71 mi) |
Comet total magnitude (M1) | 14.74 |
C/2015 ER61 (PanSTARRS) is a comet and inner Oort cloud object. When classified as a minor planet, it had the fourth-largest aphelion of any known minor planet in the Solar System, after 2005 VX3 , 2012 DR30 , and 2013 BL76 . It additionally had the most eccentric orbit of any known minor planet, with its distance from the Sun varying by about 99.9% during the course of its orbit, followed by 2005 VX3 with an eccentricity of 0.9973. On 30 January 2016, it was classified as a comet when it was 5.7 AU from the Sun. [5] It comes close to Jupiter, and a close approach in the past threw it on the distant orbit it is on now.
Though the comet nucleus was probably mildly active, early asteroidal estimates gave an absolute magnitude (H) of 12.3, [6] which would suggest a nucleus as large as 8–20 km in diameter. But it could easily be half that size due to activity brightening the nucleus.
C/2015 ER61 was discovered on 15 March 2015 when it was 8.44 AU from the Sun, [7] and magnitude 21.5. [5] By early February 2016, the object reached magnitude 20, and made a close approach to Jupiter on 28 March 2016 of 0.9245 AU. [2] This changed its orbit, significantly decreasing its aphelion distance from 1430 AU to ~1200 AU, and as it passed through the inner Solar System its aphelion decreased to 770 AU, and by 2020 it had an aphelion of 854 AU.
The barycentric orbital period will decrease from 19000 years (epoch 1950) to 9000 years (epoch 2050).
As of January 2017, it was magnitude 13, and increasing in brightness. On 4 April 2017, it was detected outbursting to magnitude 6.5. On 19 April 2017, it reached its closest point to Earth of ~1.2 AU. At this point, it was about apparent magnitude 8, [8] and, assuming a size of 20 km, have an apparent size of 19 mas. It came to perihelion (closest approach to the Sun) on 10 May 2017. [1] It will not be 50 AU from the Sun until 2045.
Dist. from Sun | Event | Epoch | Aphelion (Q) | Perihelion (q) | Semi-major axis (a) | Eccentricity (e) | Period (p) | Inclination (i) | Longitude ascending node (Ω) | Mean anomaly (M) | Argument of perihelion (ω) |
---|---|---|---|---|---|---|---|---|---|---|---|
(AU) | (AU) | (years) | (°) | ||||||||
36.5 | 2000-01-01 | 1423.4 | 1.05378 | 712.2 | 0.99852 | 18,990 | 6.12745 | 239.06 | 359.671 | 63.99 | |
20.2 | 2010-01-01 | 1435.4 | 1.05377 | 718.2 | 0.99853 | 19,240 | 6.12732 | 239.03 | 359.862 | 64.01 | |
9.01 | 2015-01-01 | 1430.8 | 1.05347 | 715.9 | 0.99853 | 19,140 | 6.12819 | 238.97 | 359.956 | 64.08 | |
8.44 | discovery | 2015-03-15 | 1436.1 | 1.05313 | 718.6 | 0.99853 | 19,250 | 6.12879 | 238.95 | 359.960 | 64.11 |
6.00 | 2016-01-01 | 1667.3 | 1.04763 | 834.2 | 0.99874 | 24,080 | 6.15827 | 238.25 | 359.980 | 64.92 | |
5.204 | Jupiter approach | 2016-03-28 | 1291.9 | 1.04030 | 646.5 | 0.99839 | 16,420 | 6.24250 | 236.73 | 359.976 | 66.64 |
2.242 | 2017-01-01 | 324.6 | 1.03505 | 162.8 | 0.99364 | 2,080 | 6.34928 | 235.27 | 359.939 | 68.46 | |
1.079 | Earth approach | 2017-04-04 | 164.3 | 1.03830 | 82.7 | 0.98744 | 750 | 6.34595 | 235.27 | 359.953 | 68.30 |
1.0397 | Perihelion | 2017-05-10 | 210.0 | 1.03973 | 105.5 | 0.99015 | 1,080 | 6.34423 | 235.25 | 0.0004 | 67.92 |
3.437 | 2018-01-01 | 1091.1 | 1.04449 | 546.1 | 0.99809 | 12,750 | 6.34438 | 235.23 | 0.018 | 68.27 | |
9.78 | 2020-01-01 | 857.8 | 1.04583 | 429.4 | 0.99756 | 8,890 | 6.34009 | 235.21 | 0.107 | 68.29 | |
56.03 | 2050-01-01 | 854.6 | 1.04649 | 427.8 | 0.99755 | 8,840 | 6.33543 | 235.18 | 1.329 | 68.34 |
^ ^ Because 2015 ER61's orbit takes it so far from the Sun, a more accurate value for its orbit is a barycentric solution. Additionally, a close approach to Jupiter in 2016, and a travel through the inner solar system in 2017 drastically changes its orbit. Therefore, orbits for 2000–2016 and 2018–2100 are provided, respectively.
10P/Tempel, also known as Tempel 2, is a periodic Jupiter-family comet with a 5-year orbital period. It was discovered on July 4, 1873 by Wilhelm Tempel. At the perihelion passage on 2 August 2026 the solar elongation is calculated at 164 degrees, with apparent magnitude approximately 8, with closest approach to Earth on 3 August 2026 at a distance of 0.414 AU (61.9 million km).
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C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. In the 43 years since its discovery only two objects with higher eccentricities have been identified, 1I/ʻOumuamua (1.2) and 2I/Borisov (3.35).
94P/Russell 4 is a periodic comet in the Solar System. It fits the definition of an Encke-type comet with. It was discovered by Ken Rusell on photographic plates taken by M. Hawkins on March 7, 1984. In the discovery images, Russell estimated that the comet had an apparent magnitude of 13 and a noticeable tail of 5 arc minutes. In the year of discovery, the comet had come to perihelion in January 1984.
(523622) 2007 TG422 (provisional designation 2007 TG422) is a trans-Neptunian object on a highly eccentric orbit in the scattered disc region at the edge of Solar System. Approximately 260 kilometers (160 miles) in diameter, it was discovered on 3 October 2007 by astronomers Andrew Becker, Andrew Puckett and Jeremy Kubica during the Sloan Digital Sky Survey at Apache Point Observatory in New Mexico, United States. According to American astronomer Michael Brown, the bluish object is "possibly" a dwarf planet. It belongs to a group of objects studied in 2014, which led to the proposition of the hypothetical Planet Nine.
C/1999 F1 (Catalina) is one of the longest known long-period comets. It was discovered on March 23, 1999, by the Catalina Sky Survey. The current perihelion point is outside of the inner Solar System which helps reduce planetary perturbations to this outer Oort cloud object and keep the inbound and outbound orbital periods similar.
C/2012 K1 (PanSTARRS) is a retrograde Oort cloud comet discovered at magnitude 19.7, 8.7 AU from the Sun on 17 May 2012 using the Pan-STARRS telescope located near the summit of Haleakalā, on the island of Maui in Hawaii (U.S.).
(668643) 2012 DR30 is a trans-Neptunian object and centaur from the scattered disk and/or inner Oort cloud, located in the outermost region of the Solar System. The object with a highly eccentric orbit of 0.99 was first observed by astronomers with the Spacewatch program at Steward Observatory on 31 March 2009. It measures approximately 188 kilometers (120 miles) in diameter.
(709487) 2013 BL76 is a trans-Neptunian object and centaur from the scattered disk and Inner Oort cloud approximately 30 kilometers in diameter.
2013 AZ60 is a small Solar System body (extended centaur) from the scattered disk or inner Oort cloud. 2013 AZ60 has the 8th-largest semi-major axis of a minor planet not detected outgassing like a comet (2013 BL76, 2005 VX3 and 2012 DR30 have a larger semi-major axis).
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C/2017 U7 (PanSTARRS) is a hyperbolic comet, first observed on 29 October 2017 by astronomers of the Pan-STARRS facility at Haleakala Observatory, Hawaii, United States when the object was 7.8 AU (1.2 billion km) from the Sun. Despite being discovered only 10 days after interstellar asteroid 1I/'Oumuamua, it was not announced until March 2018 as its orbit is not strongly hyperbolic beyond most Oort Cloud comets. Based on the absolute magnitude of 10.6, it may measure tens of kilometers in diameter. As of August 2018, there is only 1 hyperbolic asteroid known, ʻOumuamua, but hundreds of hyperbolic comets are known.
C/2017 T2 (PanSTARRS) is an Oort cloud comet discovered on 2 October 2017 when it was 9.2 AU (1.38 billion km) from the Sun. The closest approach to Earth was on 28 December 2019 at a distance of 1.52 AU (227 million km). It came to perihelion on 4 May 2020 when it was safe from disintegration at 1.6 AU from the Sun.
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C/2002 VQ94 (LINEAR) is a long period comet with a comet nucleus estimated to be ≈100 km in diameter. It was discovered on 11 November 2002 by LINEAR. It only brightened to total apparent magnitude 15.7 because the perihelion point of 6.7 AU (1.00 billion km) was outside of the inner Solar System.