Aphelion in the context of "Astronomical unit"

Orcus (minor-planet designation: 90482 Orcus) is a dwarf planet located in the Kuiper belt, with one large moon, Vanth. It has an estimated diameter of 870 to 960 km (540 to 600 mi), comparable to the Inner Solar System dwarf planet Ceres. The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color, and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.

Orcus is a plutino, a trans-Neptunian object that is locked in a 2:3 orbital resonance with the ice giant Neptune, making two revolutions around the Sun to every three of Neptune's. This is much like Pluto, except that the phase of Orcus's orbit is opposite to Pluto's: Orcus is at aphelion (most recently in 2019) around when Pluto is at perihelion (most recently in 1989) and vice versa. Orcus is the second-largest known plutino, after Pluto itself. The perihelion of Orcus's orbit is around 120° from that of Pluto, while the eccentricities and inclinations are similar. Because of these similarities and contrasts, along with its large moon Vanth that can be compared to Pluto's large moon Charon, Orcus has been dubbed the "anti-Pluto". This was a major consideration in selecting its name, as the deity Orcus was the Roman/Etruscan equivalent of the Roman/Greek Pluto.

2018 AG₃₇ is a distant trans-Neptunian object and centaur that was discovered 132.2 ± 1.5 AU (19.78 ± 0.22 billion km) from the Sun, farther than any other currently observable known object in the Solar System. Imaged in January 2018 during a search for the hypothetical Planet Nine, the confirmation of this object was announced in a press release in February 2021 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo. The object was nicknamed "FarFarOut" to emphasize its distance from the Sun.2018 AG₃₇ was discovered when it was near aphelion, the farthest point from the Sun in its elliptical orbit. The object is estimated to be at least 400 km (250 mi) in diameter. Because of its extreme distance, 2018 AG₃₇ appears extremely faint with an apparent magnitude of 25—only visible to the largest telescopes in the world.

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.

2018 VG₁₈ is the second-most distant natural object ever observed in the Solar System, after 2018 AG37 (132 AU), which was also discovered by Sheppard's team in January 2018. As of 2024, 2018 VG₁₈ is 123.6 AU (18 billion km) from the Sun and is moving farther away until it reaches aphelion in 2063. While 2018 VG₁₈ is one of the most distant Solar System objects known, its orbit is not the most distant since its average orbital distance from the Sun is 82 AU, which places it in the scattered disk and the 2:9 orbital resonance with Neptune.

A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and (101429) 1998 VF31.

Many databases, for instance the JPL Small-Body Database (JPL SBDB), only list asteroids with a perihelion greater than 1.3 AU as Mars-crossers. An asteroid with a perihelion less than this is classed as a near-Earth object even though it is crossing the orbit of Mars as well as crossing (or coming near to) that of Earth. Nevertheless, these objects are listed on this page. A grazer is an object with a perihelion below the aphelion of Mars (1.67 AU) but above the Martian perihelion (1.38 AU). The JPL SBDB lists 13,500 Mars-crossing asteroids. Only 18 MCAs are brighter than absolute magnitude (H) 12.5, which typically makes these asteroids with H<12.5 more than 13 km in diameter depending on the albedo. The smallest known MCAs have an absolute magnitude (H) of around 24 and are typically less than 100 meters in diameter. There are over 21,600 known Mars-crossers of which only 5751 have received a MPC number.

The Kreutz sungrazers (/ˈkrɔɪts/ KROYTS) are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. At the far extreme of their orbits, aphelion, Kreutz sungrazers can be a hundred times farther from the Sun than the Earth is, while their distance of closest approach can be less than twice the Sun's radius. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. These sungrazers make their way from the distant outer Solar System to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.

Several members of the Kreutz family have become great comets, occasionally visible near the Sun in the daytime sky. The most recent of these was Comet Ikeya–Seki in 1965, which may have been one of the brightest comets in the last millennium. It has been suggested that another cluster of bright Kreutz system comets may begin to arrive in the inner Solar System in the next few decades.

This is a list of trans-Neptunian objects (TNOs), which are minor planets in the Solar System that orbit the Sun at a greater distance on average than Neptune, which means all of their orbits have a semi-major axis greater than 30.1 astronomical units (AU). The Kuiper belt, scattered disk, and Oort cloud are three conventional divisions of this volume of space. As of October 2025, the catalog of minor planets contains 1,037 numbered TNOs. In addition, there are 4,518 unnumbered TNOs, which have been observed since 1993.

This list consists of all types of TNO subgroups: classical Kuiper belt objects, also known as "cubewanos", the resonant trans-Neptunian objects with their main and higher-order resonant subgroups, the scattered disc objects (SDOs), and the extreme trans-Neptunian objects including the ESDOs, EDDOs, and sednoids, which have a semi-major axis of at least 150 AU and a perihelion (closest approach to the Sun) greater than that of Neptune. The list also contains several centaurs, if the object's orbit has a sufficiently large semi-major axis (a). Centaurs have unstable orbits in which the perihelion (q) is well inside of Neptune's orbit but the farthest point (aphelion, Q) is very distant.

These Solar System minor planets are the furthest from the Sun as of January 2026. The objects have been categorized by their approximate distance from the Sun on that date, and not by the calculated aphelion of their orbit. The list changes over time because the objects are moving in their orbits. Some objects are inbound and some are outbound. It would be difficult to detect long-distance comets if it were not for their comas, which become visible when heated by the Sun. Distances are measured in astronomical units (AU, Sun–Earth distances). The distances are not the minimum (perihelion) or the maximum (aphelion) that may be achieved by these objects in the future.

This list does not include near-parabolic comets of which many are known to be currently more than 100 AU (15 billion km) from the Sun, but are currently too far away to be observed by telescope. Trans-Neptunian objects are typically announced publicly months or years after their discovery, so as to make sure the orbit is correct before announcing it. Due to their greater distance from the Sun and slow movement across the sky, trans-Neptunian objects with observation arcs less than several years often have poorly constrained orbits. Particularly distant objects take several years of observations to establish a crude orbit solution before being announced. For instance, the most distant known trans-Neptunian object 2018 AG37 was discovered by Scott Sheppard in January 2018 but was announced three years later in February 2021.