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Solar System Scratchpad

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List of Distant Minor Planets found in the news, also including other objects thought to have formed in the Kuiper Belt.

2014 Distant Minor Planets in the News[]

  • 2012 VP113 (Mar 2014) - Second Inner Oort Belt object discovered. Likely a dwarf planet with half the size of Sedna. Its perihelion is only the second found to be far enough so as not to be affected by Neptune, and is thus "detached" from the main part of the Solar System. Its argument of perihelion is near Sedna's, which could be signs of herding from a more distant super-Earth planet. Its origin could be a planet that was first scattered from the solar system, and then its perihelion reduced by other stars in the Sun's birth cluster. It would then have been unaffected by the planets or passing nearby stars, and thus remained stable over billions of years. Nicknamed "Biden" after the "VP" portion of its designation. Its surface is likely pink in color, indicative of forming in the gas giant region of space rather than the Kuiper Belt.

2013 Distant Minor Planets in the News[]

  • Pluto (Jul 2013) - Discovered after an extensive search for Planet X. Initially thought to be Earth size and dubbed the ninth planet, then continuously reduced in size as its brightness became clear and its large moon was discovered, until another object Eris was discovered in its region of space that was more massive than it, when it was demoted to a Dwarf Planet status. Considered by some a double dwarf planet due to its large moon. Also has three tiny moons and could support a ring system. First Kuiper Belt object discovered, in 2:3 orbital resonance with Neptune. Target of New Horizons spacecraft. Its surface may contain organics.

2012 Distant Minor Planets in the News[]

  • Phoebe (Apr 2012) - Outermost relatively large moon of Saturn. A dark large irregular moon, thought to be a planetesimal from the Kuiper Belt. It was likely spherical in its past, is about the same density as Pluto, and has a denser core. Its composition and density are more similar to KBOs than objects of the Saturnian system. Has water ice on its surface and probably liquid water in its interior at some point in its history. First satellite discovered using photography. First moon targeted by Cassini. Source of dark hemisphere of Iapetus. Smaller fragments land on Hyperion and Titan.
  • Makemake (Nov 2012) - Largest object in the Classical Kuiper Belt (dynamically hot) and third largest dwarf planet, three quarters or as big as Pluto. Second apparent brightest Kuiper Belt object in the solar system, it escaped detection for a while due to its high inclined orbit and because it was at its furthest point when discovered. The only undetected Dwarf Planet that Clyde Thombough could have detected, though it was near the galactic plain at the time. Originally named 2005 FY9 and code named Easterbunny, officially named after a creator and fertility god of Easter Island. Located in the center of the Kuiper Belt. Reddish in color, surface likely composed of frozen methane. Has no moons. Surprisingly found to have no significant atmosphere during an occultation.

2011 Distant Minor Planets in the News[]

  • Eris (Oct 2011) - The second dwarf planet found in the Kuiper Belt, briefly referred to as the 10th planet. Being more massive than Pluto and about the same size, Eris' discovery lead to a new definition of the word planet and reclassified itself, Pluto, and Ceres and Dwarf Planets. Originally designated 2003 UB313 and codenamed "Xena", it is now named after the Greek goddess of discord. Furthest body detected at time of discovery, when it was near its aphelion, nearly three times as far as Pluto. Much more dense than Pluto (and thus composed of more rock) and further away, but has about the same surface composition. Largest scattered disc object, which depending on the definition used, would also be the largest Kuiper Belt object. Color appears greyish, unlike Pluto, because it is far enough for Methane to condense on all parts of its surface, including low albedo features. Like Pluto, and unlike other large KBOs, it has Methane on its surface. Currently has no atmosphere. Its albedo is greater than freshly fallen snow, and one of the most reflective known objects in the Solar System. Has one small moon, Dysnomia, which allowed its mass to be computed as a 27% greater than Pluto's. Its size became better known than Pluto's temporarily in 2011, at 2326 km +/- 12 km, but was found to be slightly smaller when Pluto's size was remeasured. Its atmosphere may return when it gets closer, possibly revealing a patchy surface like Pluto's.
  • 2007 OR10 (Aug 2011) - Currently the largest solar system body without an official name. Tops Mike Brown's list of objects most certainly dwarf planets, and the fifth largest dwarf planet. About half its surface is covered in water ice that once spewed from ancient geysers. Nicknamed "Snow White", because it was once thought to have been a piece knocked off of Haumea and presumed white (and the "seventh dwarf" found by Mike Brown's team), it is actually one of the reddest objects known in the solar system. May be covered in a thin layer of methane, remnants of a condensed atmosphere. Spectrum is similar to the smaller Quauar, which also is red with water ice, and lost all its atmosphere to space. This object has almost lost all of its atmosphere. A scattered disk object in 3:10 resonance with Neptune, and currently the second furthest out known other than Eris.
  • Haumea (May 2011) - Fifth dwarf planet recognized, originally called 2003 EL61. Discovery claimed by two teams, one was able to claim discovery, while another to name the object. Originally code named Santa, now named after a goddess, whose body was broken up to form the Hawaiian island. Though to have broken up 4.5 BYA and formed two satellites (made of pure water ice), in addition to a family that shares its orbit (some of which became comets), the first such family found in the Kuiper Belt. Its satellites are unusual in that they are not coplanar. Originally classified as a classic Kuiper Belt object, it has now been shown to be in 7:12 orbital resonance with Neptune. In a highly inclined orbit similar to Makemake and the third apparent brightest body in the Kuiper Belt. Spins so fast (4 hours), that it is shaped somewhat like a cigar, yet remains in hydrostatic equilibrium. Likely mostly rock with a thin layer of water ice, unusual in that it doesn't show signs of Methane. Surface is mottled, with a large red spot high in organics, possibly a crater, though not as extreme as Pluto. Its surface appears to by crystalline ice, which is caused by tidal forces with its moon and radiogenic elements.
  • 2010 EK139 (Aug 2011) - One of three dwarf-planet sized objects found during a comprehensive search of the Kuiper Belt in 2010.
  • 2010 KZ39 (Aug 2011) - One of three dwarf-planet sized objects found during a comprehensive search of the Kuiper Belt in 2010.
  • 2010 FX86 (Aug 2011) - One of three dwarf-planet sized objects found during a comprehensive search of the Kuiper Belt in 2010.

2010 Distant Minor Planets in the News[]

  • 2002 TX300 - Minor Planet 55636, 2002 TX300, is one of the largest members of the Haumea collision family. It was found to be almost completely covered in ice with a high albedo. It is not certain why it has not accumulated dark material. Stellar occultation (the first successful one for any KBO) found it to be 89 miles across and a potential dwarf planet.

2009 Distant Minor Planets in the News[]

2008 Distant Minor Planets in the News[]

  • 2006 SQ372 (Aug 2008) - A Scattered-Disk Centaur. Comes in closer than Neptune, but has an extremely high eccentricity, bringing it out 1570 AU, over twice as far as Sedna's. Only about 50 miles across and found only because it is near its closest point. Essentially a comet that never gets close enough to the sun to develop a tail. Possibly originated from the inner oort cloud or the kuiper belt.

2007 Distant Minor Planets in the News[]

  • Charon (Jul 2007) - Large moon of Pluto, contains a tenth of its mass, making it a double dwarf planet. Its surface is completely covered in water ice, possibly from geysers. This could imply that it has subsurface liquid water. Ammonia may be helping to keep this water liquid near the surface. Has only occulted a star twice, once in 1980, and again in 2005. Has 10% less rock than Pluto, suggesting it formed in a collision and coalesced with outer material, similar to Earth's moon. The impactors could have been each about half the size of the moon.

2006 Distant Minor Planets in the News[]

  • Triton (May 2006) - Largest moon of Neptune, modestly larger than Pluto and Eris. In an irregular orbit, possibly a captured Kuiper Belt object. A capture method involving a binary moon of Triton has been proposed. Currently has a high inclination to Neptune, high axial tilt, and retrograde orbit, but tidal forces have given it a synchronous rotation and circular orbit, and it is nearer to its planet and much larger than other irregular satellites in the Solar System. Observed by Voyager 2. Found to have ice geysers and a thin but significant atmosphere.
  • Sedna (Apr 2006) - Dwarf planet candidate orbiting in a detached orbit around the Sun, possibly the first Inner Oort Cloud object discovered. Orbit is not affected by Neptune. Detached objects with perihelions greater than 75AU have been dubbed "Sednoids" after the discovery of the second one. Could be indicative of stars effects when they were much closer than they are today when the Sun was still in a cluster. Alternatively, the fact its eccentricity has not reduced over time could point to a present day star in the Solar System. It could also be a captured dwarf planet from another star, or have been moved by a passing star. Its year is 12,000 years and size thought to be two thirds that of Pluto's. It will reach perihelion in 72 years. Its rotation was initially thought to be the slowest in the Solar System other than Venus or Mercury, which was thought to be due to a close moon, but none have been found. It was later found to have a rather typical period of 10 hours. Its name was announced before it was confirmed and numbered, but the IAU allowed it to be used officially. It is one of the reddest objects known in the solar system. It was the furthest object found prior to the discovery of Eris. When discovered, was the largest body beyond discovered since Pluto, half way between Quaoar and Pluto.
  • Patroclus (Feb 2006) - The second Jupiter Trojan to be found (first trailing Trojan found), in 1906. The only binary Trojan asteroid, with a companion Menoetius. They have similar masses and orbit a common center (122 km and 112 km at 680 km apart from the common center). The pairs's masses and densities were able to be computed, and found to be much less than normal asteroids, and more like comets. It is speculated that they (and perhaps all Jupiter Trojans) originated from the Kuiper Belt, perhaps captured by Jupiter when it was closer to the Sun.

2005 Distant Minor Planets in the News[]

  • 2004 XR190 (Dec 2005) - Possible dwarf planet with half of Pluto's mass nicknamed "Buffy". It orbits beyond the Kuiper Cliff, and is detached. It has an unusually low eccentricity (varies 52 to 62 AU), but is the largest object inclined over 45 degrees. Quite bright compared to most KBOs. It's position challenges solar system formation theories.

2004 Distant Minor Planets in the News[]

  • Quaoar (Dec 2004) - Dwarf planet candidate orbiting, 1070 km in diameter, and somewhat elongated. Largest KBO found since Pluto. Furthest out object resolved by a telescope when Hubble measured its size, and the first trans-neptunian object directly measured. Given the minor planet number 50000. Has a small moon. First KBO found larger than Ceres. Sedna was briefly thought to be the largest KBO found, but after it was displaced by Eris, Quaor was found to be larger (larger than Ceres, but smaller than Charon, though more massive), and most likely a dwarf planet. The largest dynamically cold Cubewano (smaller than Makemake, which is hot), has exceptionally low eccentricity and inclination for a Plutoid. Unusual in that it is red and has water ice on it, like a smaller version of "2007 OR10" which has already lost all of its atmosphere. Its surface was likely recently resurfaced by volcanism or an impact, suggested by the detection of ammonia hydrate and crystalline water.
  • 2002 AW197 (Nov 2004) - Probable dwarf planet cubewano located at in the edge of the Kuiper Belt. Thought to be one of the largest KBOs found (2/3 Pluto's size) before Eris. It was found to be much more reflective than expected (18%), thus smaller than Ceres. This made it possible that Pluto could be much larger in comparison to most KBOs than thought. It was later found to be larger by the Spitzer, 734 km. It is red with no sign of water ice. Mike Brown considers it highly likely to be a dwarf planet.
  • Orcus (Feb 2004) - Originally 2004 DW, the largest Plutino after Pluto. Thought of as the "anti-Pluto" because it is at perihelion when Pluto is at aphelion and vice versa. It also has a similarly large in ratio moon. Named after Pluto's Etruscan equivalent, while its moon is named after the one who ferried souls to the underworld, Vanth. It was the thought to be the largest TNO at discovery (after Quaoar), and now thought to be almost certainly a dwarf planet by Mike Brown.

2003 Distant Minor Planets in the News[]

  • 2003 BF91, 2003 BG91, 2003 BH91 (Sep 2003): Smallest trans-Neptunians objects found yet

2002 Distant Minor Planets in the News[]

2001 Distant Minor Planets in the News[]

  • Ixion (Jul 2001) - The most intrinsically bright one found at the time of its discovery in 2001. Thought to be larger than Ceres and Charon, and the largest KBO known, but now only 650 km, smaller than the previously largest known KBO Varuna, but still large enough to probably be a dwarf planet. Originally thought to be in 3:4 resonance, it is now considered a Plutino with 2:3 resonance. Currently, the fifth largest Plutino.

1998 Distant Minor Planets in the News[]

  • 1996 TO66 (Jun 1997) - First trans-Neptunian object to have its rotation period measured (6 hours, the same as Chiron). Briefly thought to be the largest KBO known, larger than 1996 TL66 found just prior to it. Has a more typical orbit, but much higher incline and closer perihelion than Cubewanos. Later found to be a member of the Haumea family, possibly in 11:19 resonance with Neptune.

1997 Distant Minor Planets in the News[]

  • 1996 TL66 (Jun 1997) - Large scattered disk object, the largest Kuiper Belt Object known at the time of its discovery. At the time, said to have the surface area of Texas. The object categorized as scattered disk object discovered and first to be found that goes that far out (varies from Pluto-like to three times Pluto's distance), in what was thought a no man land, located near its perihelion. Another object was found earlier though, but only later recognized as being in the scattered disk. Probably a dwarf planet according to Mike Brown.

1995 Distant Minor Planets in the News[]

  • Chiron (Jan 1995) - The second Centaur discovered, and the first recognized as one. Orbits between Saturn and Uranus, just barely crossing each of these planets orbits, and was found when at aphelion (1977) and the furthest detected object at the time. When it approached perihelion (reached in 1996), cometary activity was detected, which did not include water because water does not sublimate at its distances One of the only ones known to have cometary activity and classified as an asteroid an a comet. Has a larger nucleus than any comet. Evidence that its coma comes from a few localized jet-forming areas on its surface, rather than its surface as a whole. Thought to be a newcomer to its orbit since it still has cometary activity and is in a relatively unstable location. It is a potential dwarf planet with a radius of 233 km, and the second largest centaur, possibly the largest.

1993 Distant Minor Planets in the News[]

  • 1993 SC - One of the first four Plutinos which were discovered within four days of each other, the last of these to be discovered, but the first to be confirmed, and the object with the largest absolute magnitude known at the time (363 km, about a third of Charon). The first to have its spectra taken with high resolution. Its color was in between Pholus and Chiron's, demonstrating that not all KBOs were extremely red. Also shown to have methane on its surface.
  • 1993 SB - One of the first four Plutinos that were discovered, each a day apart. The third to be detected, but the first to have its orbit calculated ell enough to confirm.
  • 1993 RP - Second small Plutino discovered, a day after the first one, and followed up by two more, each a day later. The smallest known KBO at the time, around 70 km across.
  • 1993 RO - The first Plutino discovered after Pluto, along with three others detected within three days. Its discoverer noted it was 30 from Neptune, possibly suggesting it could be a Trojan, but it turned out to be in 2:3 Resonance instead.
  • 1993 FW (Mar 1993) - The second classic kuiper belt object discovered. Discovered in the same survey as 1992 QB1. Finding two objects in a small patch of the sky implied that there were many objects beyond Pluto, instead of a tenth Planet X.

1992 Distant Minor Planets in the News[]

  • 1992 QB1 (Aug 1992) - The first trans-Neptunian object discovered after Pluto. It was the first classical Kuiper Belt object discovered and other objects in this portion of the belt (just beyond Neptune, low eccentricity, not in resonance with Neptune) are called "Cubewano"s in its honor. Also has a low inclination, making it a dynamically cold classical KBO. Its discoverer suggested the name Smiley, but this was already used for an asteroid. About 160 km across.

General News[]

Outer Edge of Kuiper Belt Discerned (Oct 2000)[]

Hubble Finds Many Binary KBOs (Apr 2002)[]

Smallest trans-Neptunians objects found yet (Sep 2003)[]

2003 BF91, 2003 BG91, 2003 BH91 found by Hubble, smallest past Neptune yet (15-28 miles)
Only 3 were found of this size, when at least 60 as small as 10 miles were expected

Chunks of Rock Detected (Aug 2006)[]

Enduring Mysteries (Dec 2007)[]

Smallest KBO Detected Via Occultation by Hubble (Dec 2009)[]

Consistently Red Cold Classical KBOs Could Be Organics and Point to Origin of Life (Oct 2010)[]

Reference: Oort Cloud (Jul 2012)[]