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Discovery site Subaru Telescope
Discovery date 13 October 2015
Orbital characteristics
Observation arc ~2 weeks as of 2015 announcement[2]
Perihelion >50 AU?[a]
>150 AU?
Physical characteristics
Dimensions 500–1000 km[1][3]

V774104 is a trans-Neptunian object (TNO) with a radius roughly half that of Pluto or somewhat smaller. When the discovery was announced in November 2015, based on a short observation arc of 2 weeks,[5][6] it was believed to be approximately 103 AU from the Sun, a distance of 15.4 billion kilometers (9.6 billion miles).[7] This would have made it the most distant observed natural object in the Solar System.[6][8] No astrometry has been submitted to the Minor Planet Center, so there are no publicly known orbital elements.


The object's discovery telescope, Subaru (Japanese name for the Pleiades) on the far left, alongside the twin Keck telescopes and NASA's Infrared Telescope Facility

V774104 was discovered by Scott S. Sheppard, Chad Trujillo, and David J. Tholen using the Subaru Telescope, a large reflecting telescope at the summit of Mauna Kea with a primary mirror 8 meters (26 ft) in diameter.[1][3] It was discovered in the direction of west-central Pisces.[1] The discovery was announced at the November 2015 meeting of the American Astronomical Society’s Division for Planetary Sciences.[8] 2015 TG387, 2015 TH367, and 2015 TJ367 were also discovered by this team on 13 October 2015.


No astrometry has been released publicly so the object does not have a minor planet designation and the uncertainties of the orbital elements are unknown. Being a trans-Neptunian object so far from the Sun with an observation arc of just a few weeks at the time of its discovery announcement,[2] its perihelion and aphelion initially have not been securely determined.[c]

Possible sednoid[edit]

The orbit of Sedna (in red), the prototypical sednoid, set against the orbits of Pluto (purple) and the outer planets

V774104 appears to be a sednoid, an enigmatic class of objects in the outer Solar System with only two known members. Sednoids have eccentric orbits that must have been perturbed by something, but could not have been perturbed by any presently known body (their entire orbits lie well outside the influence of Neptune). To be a sednoid, V774104 must have a perihelion greater than 50 AU and a semi-major axis greater than 150 AU, which can be determined when its observation arc is around one year. In 2015, only 3 published objects were known to have perihelia (closest approach to the Sun) greater than 50 AU: 90377 Sedna, 2012 VP113, and 2004 XR190.[10][11] But 2004 XR190 has a low orbital eccentricity with perihelion at 51 AU.[10] In 2014 and 2015, three further bodies similar to 2004 XR190 were discovered with perihelion between 50 and 56 AU.[12][13] Sedna and 2012 VP113 have both had their perihelion point lifted well beyond the classic Kuiper belt of 30–50 AU. If V774104 is confirmed to be a sednoid or extreme trans-Neptunian object, it may point towards an undiscovered shepherding planet hundreds of astronomical units from the Sun.[3][7] It is also possible, however, that the lifted perihelion was a result of the crowded confines of the open star cluster in which the Sun formed.[3] Discovery of additional sednoids and analysis of their orbits should eventually permit identification of the process by which their orbits were disturbed.[14]

Most distant Solar System object[edit]

Many news sources heralded V774104 as "the most distant Solar System object".[8] In fact, various long-period and hyperbolic comets are more distant,[7] though all of these are much smaller bodies and not observable at such distances.[d] Since the time of its discovery, the Voyager and Pioneer 10 spacecraft have also been more distant; the Voyager probes are observable via their artificial radio transmissions.

Observed Solar System objects that periodically become more distant than 103 AU from the Sun include Sedna (which is similar or modestly larger in size), 2000 CR105, 2012 DR30, 2013 BL76, and 2005 VX3. There are 726 known objects that have aphelia more than 103 AU from the Sun.[16] This distance is about double the outer limit of the torus-shaped Kuiper belt that lies outside Neptune's orbit. Far beyond this region is the vast spherical Oort cloud enshrouding the Solar System, whose presence was deduced from the orbits of long-period comets.

Study of the population of Solar System objects that are significantly more distant than V774104 will likely require new instruments. The proposed Whipple spacecraft mission is designed to determine the outer limit of the Kuiper belt and directly detect Oort cloud objects out to 10,000 AU. Such objects are too small to detect with current telescopes except during stellar occultations. The proposal involves use of a wide field of view and rapid recording cadence to allow detection of many such events.[17]

See also[edit]


  1. ^ To be a Sednoid, V774104 must have a perihelion (closest approach to the Sun) of no less than 50 AU and a semi-major axis (average orbital distance) greater than 150 AU.
  2. ^ The size estimate of 500–1000 km leads to an absolute magnitude (H) of 3.5–4.0, which at 103 AU is apparent magnitude 24–24.5.
  3. ^ For comparison Trans-Neptunian object 2015 SO20 with an observation arc of only 28 days had large uncertainties for perihelion and aphelion.[9]
  4. ^ For example, as of 2015, comet C/1927 X1 (Skjellerup-Maristany) is 109 AU from the Sun


  1. ^ a b c d e f Beatty, Kelly (21 November 2015). "V774104: Solar System's Most Distant Object". Sky & Telescope. Retrieved 22 November 2015.
  2. ^ a b Cofield, Calla (12 November 2015). "New Dwarf Planet In Our Solar System May Be The Farthest One Yet". Space.com. Retrieved 13 November 2015.
  3. ^ a b c d Sokol, Joshua (10 November 2015). "Most distant solar system object yet could hint at hidden planet". New Scientist.
  4. ^ "Absolute Magnitude (H)". NASA/JPL.
  5. ^ Temperton, James (11 November 2015). "Solar System's most distant object hints at hidden planet". Wired.
  6. ^ a b Hand, Eric (10 November 2015). "Astronomers spot most distant object in the solar system, could point to other rogue planets". Science. Retrieved 11 November 2015.
  7. ^ a b c "Newly discovered dwarf planet is solar system's most distant object". Astronomy Now. 12 November 2015.
  8. ^ a b c Amos, Jonathan (11 November 2015). "'Most distant' Solar System object spied". BBC News.
  9. ^ "JPL Small-Body Database Browser: (2015 SO20)" (last observation: 18 October 2015 ; arc: 28 days). Jet Propulsion Laboratory. Archived from the original on 16 November 2015. Retrieved 13 November 2015.
  10. ^ a b "JPL Small-Body Database Search Engine: q > 50 (AU)". JPL Solar System Dynamics. Archived from the original on 13 November 2015. Retrieved 12 November 2015.
  11. ^ "Minor Planet Center: q > 50 (AU)". Minor Planet Center. Retrieved 12 November 2015.
  12. ^ Sheppard, Scott S.; Trujillo, Chadwick; Tholen, David J. (July 2016). "Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects with Moderate Semimajor Axes and Eccentricities". The Astrophysical Journal Letters. 825 (1). L13. arXiv:1606.02294. Bibcode:2016ApJ...825L..13S. doi:10.3847/2041-8205/825/1/L13.
  13. ^ Minor Planet Center (2017). "MPC Database Search for 2014 FC72". Retrieved 23 October 2017.
  14. ^ Schwamb, Megan E. (18 September 2007). Searching for Sedna's Sisters: Exploring the inner Oort cloud (PDF) (Report). Caltech. Archived from the original (PDF) on 12 May 2013.
  15. ^ a b "AstDyS-2, Asteroids - Dynamic Site". Retrieved 2018-04-03. Objects with distance from Sun over 59 AU
  16. ^ "JPL Small-Body Database Search Engine: Q > 103 (AU)". JPL Solar System Dynamics. Retrieved 12 March 2018.
  17. ^ Alcock, C.; et al. The Whipple Mission: Exploring the Oort Cloud and the Kuiper Belt (PDF). American Geophysical Union, Fall Meeting 2014. 11-19 December 2014. San Francisco, California. Bibcode:2014AGUFM.P51D3977A. Archived from the original (PDF) on 17 November 2015.