List of Solar System objects by greatest aphelion

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The orbit of Sedna (red) set against the orbits of outer Solar System objects (Pluto's orbit is purple). Sedna orbit.svg
The orbit of Sedna (red) set against the orbits of outer Solar System objects (Pluto's orbit is purple).

This is a list of Solar System objects by greatest aphelion or the greatest distance from the Sun that the orbit could take it if the Sun and object were the only objects in the universe. It is implied that the object is orbiting the Sun in a two-body solution without the influence of the planets, passing stars, or the galaxy. The aphelion can change significantly due to the gravitational influence of planets and other stars. Most of these objects are comets on a calculated path and may not be directly observable. [1] For instance, comet Hale-Bopp was last seen in 2013 at magnitude 24 [2] and continues to fade, making it invisible to all but the most powerful telescopes.

Contents

The maximum extent of the region in which the Sun's gravitational field is dominant, the Hill sphere, may extend to 230,000 astronomical units (3.6 light-years) as calculated in the 1960s. [3] But any comet currently more than about 150,000  AU (2  ly ) from the Sun can be considered lost to the interstellar medium. The nearest known star is Proxima Centauri at 269,000 AU (4.25 ly), [4] followed by Alpha Centauri at about 4.35 light years. [4]

Oort cloud comets orbit the Sun at great distances, but can then be perturbed by passing stars and the galactic tides. [5] As they come into or leave the inner Solar System they may have their orbit changed by the planets, or alternatively be ejected from the Solar System. [5] It is also possible they may collide with the Sun or a planet. [5]

S/2021 N 1 (the outermost moon of Neptune) takes over 27 years to orbit Neptune, comets can take up to 30 million years to orbit the Sun, and the Sun orbits the Milky Way in about 230 million years (a galactic year).

Satellite orbital period vs parent body orbital period
Satellite Orbital period
(years)		Parent bodyPercentage of
parent body
orbital period
S/2021 N 1 27.4 Neptune 16.6%
Oort cloud comet30 million Sun 13%
Sun 230 million Milky Way N/A

Explanation

Barycentric vs heliocentric orbits

Motion of the Solar System's barycenter relative to the Sun Solar system barycenter.svg
Motion of the Solar System's barycenter relative to the Sun

As many of the objects listed below have some of the most extreme orbits of any objects in the Solar System, describing their orbit precisely can be particularly difficult and sensitive to the time the orbit is defined at. For most objects in the Solar System, a heliocentric reference frame (relative to the gravitational center of the Sun) is sufficient to explain their orbits. However, as the orbits of objects become closer to the Solar System's escape velocity, with long orbital periods on the order of hundreds or thousands of years, a different reference frame is required to describe their orbit: a barycentric reference frame. A barycentric reference frame measures the asteroid's orbit relative to the gravitational center of the entire Solar System, rather than just the Sun. Mostly due to the influence of the outer gas giants, the Solar System barycenter varies by up to twice the radius of the Sun.

This difference in position can lead to significant changes in the orbits of long-period comets and distant asteroids. Many comets have hyperbolic (unbound) orbits in a heliocentric reference frame, but in a barycentric reference frame have much more firmly bound orbits, with only a small handful remaining truly hyperbolic.

Eccentricity and Vinf

The orbital parameter used to describe how non-circular an object's orbit is, is eccentricity (e). An object with an e of 0 has a perfectly circular orbit, with its perihelion distance being just as close to the Sun as its aphelion distance. An object with an e of between 0 and 1 will have an elliptical orbit, with, for instance, an object with an e of 0.5 having a perihelion twice as close to the Sun as its aphelion. As an object's e approaches 1, its orbit will be more and more elongated before, and at e=1, the object's orbit will be parabolic and unbound to the Solar System (i.e. not returning for another orbit). An e greater than 1 will be hyperbolic and still be unbound to the Solar System.

Although it describes how "unbound" an object's orbit is, eccentricity does not necessarily reflect how high an incoming velocity said object had before entering the Solar System (a parameter known as Vinfinity, or Vinf). A clear example of this is the eccentricities of the two known Interstellar objects as of October 2019, 1I/'Oumuamua. and 2I/Borisov. 'Oumuamua had an incoming Vinf of 26.5 kilometres per second (59,000 mph), but due to its low perihelion distance of only 0.255 au, it had an eccentricity of 1.200. However, Borisov's Vinf was only slightly higher, at 32.3 km/s (72,000 mph), but due to its higher perihelion distance of ~2.003 au, its eccentricity was a comparably higher 3.340. In practice, no object originating from the Solar System should have an incoming heliocentric eccentricity much higher than 1, and should rarely have an incoming barycentric eccentricity of above 1, as that would imply that the object had originated from an indefinitely far distance from the Sun.

Orbital epochs

Due to having the most eccentric orbits of any Solar System body, a comet's orbit typically intersects one or more of the planets in the Solar System. As a result, the orbit of a comet is frequently perturbed significantly, even over the course of a single pass through the inner Solar System. Due to the changing orbit, it's necessary to provide a calculation of the orbit of the comet (or similarly orbiting body) both before and after entering the inner Solar System. For example, Comet ISON was ~312 au from the Sun in 1600, and its remnants will be ~431 au from the Sun in 2400, both well outside of any significant gravitational influence from the planets.

Comets with greatest aphelion (2 body heliocentric)

C/1910 A1 during its 1910 close approach Comet 1910 A1.jpg
C/1910 A1 during its 1910 close approach
Proxima Centauri is 271,000 AU or 4.25 light years away New shot of Proxima Centauri, our nearest neighbour.jpg
Proxima Centauri is 271,000 AU or 4.25 light years away

Distant comets with long observation arcs and/or barycentric

Comet West in 1976 C-west-1976-ps.jpg
Comet West in 1976

Examples of comets with a more well-determined orbit. Comets are extremely small relative to other bodies and hard to observe once they stop outgassing (see Coma (cometary)). Because they are typically discovered close to the Sun, it will take some time even thousands of years for them to actually travel out to great distances. The Whipple proposal might be able to detect Oort cloud objects at great distances, but probably not a particular object.

Minor planets

Number of minor planets (January 2024)
Aphelion
in AU		Number of minor planets
400-800
36
800-1200
15
1200-1600
7
1600-2000
4
2000-2400
5
2400-2800
2
2800+
3

A large number of trans-Neptunian objects (TNOs) – minor planets orbiting beyond the orbit of Neptune – have been discovered in recent years. Many TNOs have orbits that take them far beyond Pluto's aphelion of 49.3  AU. Some of these TNOs with an extreme aphelion are detached objects such as 2010 GB174 , which always reside in the outermost region of the Solar System, while for other TNOs, the extreme aphelion is due to an exceptionally high eccentricity such as for 2005 VX3 , which orbits the Sun at a distance between 4.1 (closer than Jupiter) and 2200 AU (70 times farther from the Sun than Neptune). The following is a list of minor planets with the largest aphelion in descending order. [16]

Minor planets with a heliocentric aphelion greater than 400 AU

The following group of bodies have orbits with an aphelion above 400 AU, with 1-sigma uncertainties given to two significant digits. As of May 2024, there are 73 such bodies. [16]

Orbits of three known sednoids: Sedna, 2012 VP113, and Leleakuhonua Sednoid orbits.png
Orbits of three known sednoids: Sedna, 2012 VP113 , and Leleākūhonua

Greatest barycentric aphelion

The following asteroids have an incoming barycentric aphelion of at least 1000 AU.[ citation needed ]

Comparison

The orbit of Sedna, 2012 VP113, Leleakuhonua, and other very distant objects along with the predicted orbit of Planet Nine. The three sednoids (pink) along with the red-colored extreme trans-Neptunian object (eTNO) orbits are suspected to be aligned with the hypothetical Planet Nine while the blue-colored eTNO orbits are anti-aligned. The highly elongated orbits colored brown include centaurs and damocloids with large aphelion distances over 200 AU. Distant object orbits + Planet Nine.png
The orbit of Sedna, 2012 VP113 , Leleākūhonua, and other very distant objects along with the predicted orbit of Planet Nine. The three sednoids (pink) along with the red-colored extreme trans-Neptunian object (eTNO) orbits are suspected to be aligned with the hypothetical Planet Nine while the blue-colored eTNO orbits are anti-aligned. The highly elongated orbits colored brown include centaurs and damocloids with large aphelion distances over 200 AU.

See also

About comets
Objects of interest
Others

Related Research Articles

<span class="mw-page-title-main">Comet Machholz</span>

Comet Machholz, formally designated C/2004 Q2, is a long-period comet discovered by Donald Machholz on August 27, 2004. It reached naked eye brightness in January 2005. Unusual for such a relatively bright comet, its perihelion was farther from the Sun than the Earth's orbit.

<span class="mw-page-title-main">C/2006 M4 (SWAN)</span>

Comet C/2006 M4 (SWAN) is a non-periodic comet discovered in late June 2006 by Robert D. Matson of Irvine, California and Michael Mattiazzo of Adelaide, South Australia in publicly available images of the Solar and Heliospheric Observatory (SOHO). These images were captured by the Solar Wind ANisotropies (SWAN) Lyman-alpha all-sky camera on board the SOHO. The comet was officially announced after a ground-based confirmation by Robert McNaught on July 12.

Comet Zhu–Balam is a long-period comet first identified by David D. Balam on June 8, 1997, and originally photographed by Jin Zhu on June 3, 1997. The comet is estimated at 10 kilometres in diameter with a period of approximately 36,800 years.

474640 Alicanto (provisional designation 2004 VN112) is a detached extreme trans-Neptunian object. It was discovered on 6 November 2004, by American astronomer Andrew C. Becker at Cerro Tololo Inter-American Observatory in Chile. It never gets closer than 47 AU from the Sun (near the outer edge of the main Kuiper belt) and averages more than 300 AU from the Sun. Its large eccentricity strongly suggests that it was gravitationally scattered onto its current orbit. Because it is, like all detached objects, outside the current gravitational influence of Neptune, how it came to have this orbit cannot yet be explained. It was named after Alicanto, a nocturnal bird in Chilean mythology.

<span class="nowrap">(308933) 2006 SQ<sub>372</sub></span> Trans-Neptunian object and highly eccentric centaur

(308933) 2006 SQ372 is a trans-Neptunian object and highly eccentric centaur on a cometary-like orbit in the outer region of the Solar System, approximately 123 kilometers (76 miles) in diameter. It was discovered through the Sloan Digital Sky Survey by astronomers Andrew Becker, Andrew Puckett and Jeremy Kubica on images first taken on 27 September 2006 (with precovery images dated to 13 September 2005).

<span class="mw-page-title-main">C/1992 J1 (Spacewatch)</span>

C/1992 J1 (Spacewatch) is a comet that was discovered 1 May 1992 by David Rabinowitz of the Spacewatch Project. This was the first comet to be discovered using an automated system.

<span class="mw-page-title-main">C/1980 E1 (Bowell)</span> Non-periodic comet

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).

<span class="nowrap">(523622) 2007 TG<sub>422</sub></span> Trans-Neptunian object

(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.

<span class="nowrap">(668643) 2012 DR<sub>30</sub></span> Trans-Neptunian object and centaur

(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.

<span class="nowrap">(709487) 2013 BL<sub>76</sub></span> Trans-Neptunian object

(709487) 2013 BL76 is a trans-Neptunian object and centaur from the scattered disk and Inner Oort cloud approximately 30 kilometers in diameter.

2005 VX3 is trans-Neptunian object and retrograde damocloid on a highly eccentric, cometary-like orbit. It was first observed on 1 November 2005, by astronomers with the Mount Lemmon Survey at the Mount Lemmon Observatory in Arizona, United States. The unusual object measures approximately 7 kilometers (4 miles) in diameter. It has the 3rd largest known heliocentric semi-major axis and aphelion. Additionally its perihelion lies within the orbit of Jupiter, which means it also has the largest orbital eccentricity of any known minor planet.

<span class="mw-page-title-main">Extreme trans-Neptunian object</span> Solar system objects beyond the other known trans-Neptunian objects

An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30 AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ETNOs are much less affected by the known giant planets than all other known trans-Neptunian objects. They may, however, be influenced by gravitational interactions with a hypothetical Planet Nine, shepherding these objects into similar types of orbits. The known ETNOs exhibit a highly statistically significant asymmetry between the distributions of object pairs with small ascending and descending nodal distances that might be indicative of a response to external perturbations.

2010 BK118 (also written 2010 BK118) is a centaur roughly 20–60 km in diameter. It is on a retrograde cometary orbit. It has a barycentric semi-major axis (average distance from the Sun) of ~400 AU.

(418993) 2009 MS9, provisionally known as 2009 MS9, is a centaur roughly 30–60 km in diameter. It has a highly inclined orbit and a barycentric semi-major axis (average distance from the Sun) of ~353 AU.

(336756) 2010 NV1 (provisional designation 2010 NV1) is a highly eccentric planet crossing trans-Neptunian object, also classified as centaur and damocloid, approximately 52 kilometers (32 miles) in diameter. It is on a retrograde cometary orbit. It has a barycentric semi-major axis (average distance from the Sun) of approximately 286 AU.

<span class="nowrap">2014 FE<sub>72</sub></span> Extreme trans-Neptunian object from the inner Oort cloud

2014 FE72 is a trans-Neptunian object first observed on 26 March 2014, at Cerro Tololo Inter-American Observatory in La Serena, Chile. It is a possible dwarf planet, a member of the scattered disc, whose orbit extends into the inner Oort cloud. Discovered by Scott Sheppard and Chad Trujillo, the object's existence was revealed on 29 August 2016. Both the orbital period and aphelion distance of this object are well constrained. 2014 FE72 had the largest barycentric aphelion until 2018. However, the heliocentric aphelion of 2014 FE72 is second among trans-Neptunian objects (after the damocloid 2017 MB7). As of 2023, it is about 66 AU (9.9 billion km) from the Sun.

2017 MB7 is a trans-Neptunian object and damocloid on a cometary-like orbit from the outer Solar System, approximately 6 kilometers (4 miles) in diameter. It was first observed on 22 June 2017 by the Pan-STARRS survey at Haleakala Observatory in Hawaii, United States. This unusual object has the largest heliocentric aphelion, semi-major axis, orbital eccentricity and orbital period of any known periodic minor planet, even larger than that of 2014 FE72; it is calculated to reach several thousand AU (Earth-Sun) distances at the farthest extent of its orbit.

<span class="nowrap">2018 VG<sub>18</sub></span> Trans-Neptunian object @ 123AU

2018 VG18 is a distant trans-Neptunian object (TNO) that was discovered when it was 123 AU (18 billion km; 11 billion mi) from the Sun, more than three times the average distance between the Sun and Pluto. It was discovered on 10 November 2018 by Scott Sheppard, David Tholen, and Chad Trujillo during their search for TNOs whose orbits might be gravitationally influenced by the hypothetical Planet Nine. They announced the discovery of 2018 VG18 on 17 December 2018 and nicknamed the object "Farout" to emphasize its distance from the Sun.

References

  1. 1 2 JPL Small-Body Database Search Engine: Q > 20000 (au)
  2. ↑ "C/1995 O1 (Hale-Bopp)". Minor Planet Center. Retrieved 14 March 2018.
  3. ↑ Chebotarev, G.A. (1964), "Gravitational Spheres of the Major Planets, Moon and Sun", Soviet Astronomy, 7 (5): 618–622, Bibcode:1964SvA.....7..618C
  4. 1 2 NASA – Imagine the Universe: The Nearest Star
  5. 1 2 3 Frequently Asked Questions About General Astronomy
  6. ↑ Barycentric solution for 2004 R2
  7. ↑ Barycentric solution for 2015 O1
  8. ↑ Barycentric solution for 2012 S4
  9. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1975 V1-A (West)" . Retrieved 2011-02-01. (Solution using the Solar System Barycenter. Select Ephemeris Type:Elements and Center:@0)
  10. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1999 F1 (Catalina)" . Retrieved 2011-03-07. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0)
  11. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/2012 S4 (PANSTARRS)" . Retrieved 2015-09-26. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0)
  12. ↑ Horizons output (2011-01-30). "Barycentric Osculating Orbital Elements for Comet Hyakutake (C/1996 B2)" . Retrieved 2011-01-30. (Horizons)
  13. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1910 A1 (Great January comet)" . Retrieved 2011-02-07. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0)
  14. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1992 J1 (Spacewatch)" . Retrieved 7 October 2012. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0)
  15. ↑ Horizons output. "Barycentric Osculating Orbital Elements for Comet Lulin (C/2007 N3)" . Retrieved 2011-01-30. (Solution using the Solar System Barycenter. Select Ephemeris Type:Elements and Center:@0)
  16. 1 2 "Small-Body Database Query". ssd.jpl.nasa.gov. Retrieved 2024-05-09.
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