is a
trans-Neptunian object
A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).
...
and the tenth-most-distant known object in the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
. Considered a
detached object
Detached objects are a dynamical class of minor planets in the outer reaches of the Solar System and belong to the broader family of trans-Neptunian objects (TNOs). These objects have orbits whose points of closest approach to the Sun ( perihe ...
,
it orbits the
Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
in a highly eccentric orbit every 3,305 years at an average distance of 222
astronomical unit
The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...
s (AU).
[
]
Description
Mike Brown's website lists it as a possible dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...
with a diameter of based on an assumed albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
of 0.04 .[ The albedo is expected to be low because the object has a ]blue
Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spe ...
(neutral) color.Neptune
Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
even at their perihelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values.
Apsides perta ...
distances (closest approaches to the Sun). It is something of a mystery as to how these objects came to be in their current, far-flung orbits. Several hypotheses have been put forward:
* They were pulled from their original positions by a passing star.[
]
* They were pulled from their original positions by a very distant, and as-yet-undiscovered (albeit unlikely), giant planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
.Nemesis
In ancient Greek religion and myth, Nemesis (; ) also called Rhamnousia (or Rhamnusia; ), was the goddess who personified retribution for the sin of hubris: arrogance before the gods.
Etymology
The name ''Nemesis'' is derived from the Greek ...
.[
* They were captured from another ]planetary system
A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...
during a close encounter early in the Sun's history.[ According to Kenyon and Bromley, there is a 15% probability that a star like the Sun had an early close encounter and a 1% probability that outer planetary exchanges would have happened. is estimated to be 2–3 times more likely to be a captured planetary object than Sedna.][
is the first object discovered in the Solar System to have a ]semi-major axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...
exceeding 150 AU, a perihelion beyond Neptune, and an argument of perihelion of .[ It may be influenced by ]Planet Nine
Planet Nine is a List of hypothetical Solar System objects, hypothetical ninth planet in the outer region of the Solar System. Its gravitational effects could explain the peculiar clustering of orbits for a group of extreme trans-Neptunian obj ...
.[
]
See also
* 474640 Alicanto
*
* Clearing the neighbourhood
* Planets beyond Neptune
Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century and continued at the start of the 20th with Percival Lowell's ...
* List of Solar System objects most distant from the Sun
These Solar System minor planets are the furthest from the Sun . The objects have been categorized by their approximate current distance from the Sun, and not by the calculated aphelion of their orbit. The list changes over time because the obj ...
* List of Solar System objects by greatest aphelion
References
External links
Orbit Determination of
Spacecraft escaping the Solar System
(Heavens-Above)
* World Book
*
*
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148209
Discoveries by Marc Buie
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