The scattered disk (sometimes spelt as "scattered disc") is a dynamical subset of the Kuiper belt[1] sparsely populated by various icy minor planets. Where the scattered disk starts and ends cannot be precisely determined—the Kuiper cliff is generally agreed to be its starting point, which is around 55 AU from the Sun.[2] The ending point of the scattered disk is generally considered to be the outer edge of what is known as the "parking zone," which lies at about 1,000 AU.[3]
The objects that lie within the scattered disk have extremely eccentric and distant orbits. The orbits of SDOs can swing as close to the Sun as 30 AU, but their orbits can reach far past 60 AU.[4] These highly eccentric orbits are believed to be caused by gravitational "scattering" during the early-to-mid Solar System by the gas giants, most notably Neptune. Some scientists believe the eccentricity is caused by a hypothetical Planet Nine.[5]
Due to its extreme distance from the Sun and instability, the scattered disk is believed to be the origin for most periodic comets in the solar system, and many supposed Oort Cloud objects are also thought to originate from the scattered disk.[1]
Discovery[]
The concept of the scattered disk was suggested as early as 1980 by Julio A. Fernández. He suggested the idea of a "comet belt" located beyond Neptune that consists of various planetesimals that "became subject to the strong perturbations of Neptune."[6] However, because the idea of the Kuiper belt did not exist at the time, there was little actual evidence to prove the existence of it. In 1992, the first TNO—15760 Albion—was discovered, which proved the existence of the Kuiper belt.
Following its discovery, various search campaigns were spearheaded specifically to search for more small solar system bodies beyond Neptune. 1996 TL66 was discovered during a survey in 1996, and was observed to have a highly eccentric orbit with an aphelion of around 130 AU. It soon became the first celestial body to be classified as an SDO. A deeper survey in February 1999 led to the discovery of three more SDOs, confirming the existence of the scattered disk as a separate entity from the classical Kuiper belt.[7]
Scattered Disk Objects (SDOs)[]
Scattered disk objects (SDOs)—also known as Scattered Kuiper belt objects (SKBOs)—are small solar system bodies that lie within the scattered disk. They are believed to have originated due to gravitational scattering from Neptune, and as a result, have highly eccentric orbits. Their aphelia often extend well beyond 100 AU, while their perihelia swing close to Neptune's orbit.
Most SDOs are poorly documented and very few small SDOs have been observed. Due to their extreme distances, it's difficult to observe them, and even so, they all have slight similarities. Most SDOs are primarily composed of water ice and are some of the coldest bodies in the solar system.
There is a variant of SDOs called extended scattered disk objects (ESDOs), in which their perihelia are distant from Neptune's orbit and thus aren't as affected by its gravity. They are sometimes called detached objects because their minimal influence from Neptune essentially makes them "detached" from the rest of the solar system.[8] ESDOs have significantly more eccentric and distant orbits than normal SDOs due to their detached nature. A notable subcategory of ESDOs are sednoids.
Largest SDOs[]
Because there are many SDOs, only those with a mean diameter of 500 km or above will be listed. The SDOs will be listed among three categories: normal, extended, and sednoid.
| Name or Designation | Diameter (kilometers) | Margin of Error (kilometers) | IAU Dwarf Planet Status | Perihelion–Aphelion[9] | SDO Type |
|---|---|---|---|---|---|
| (136199) Eris | 2,326[10] | 12 | ✓ | 38.4–97.7 AU | Normal |
| (225088) Gonggong | 1,230[11] | 50 | ? | 33.8–101.2 AU | Normal |
| (90377) Sedna | 995[12] | 80 | ✗ | 76.2–937 AU | Sednoid |
| 2017 OF₆₉ | 700[13] | 150 | ✗ | 44.9–1,700 AU | Extended |
| (674118) 2015 KH162 | 671[14] | ✗ | 41.5–61.8 AU | Extended | |
| 2012 VP113 | 650[15] | 350 | ✗ | 80.5–462 AU | Sednoid |
| (612911) 2004 XR190 | 637.5[16] | 212.5 | ✗ | 51.1–63.4 AU | Normal |
| (229762) Gǃkúnǁʼhòmdímà | 614[17] | 15 | ✗ | 37.5–108.1 AU | Extended[18] |
| (278361) 2007 JJ43 | 610[19] | +170, -140 | ✗ | 40.3–55.4 AU | Extended |
| (528381) 2008 ST291 | 584[14] | ✗ | 42.3–99.9 AU | Extended | |
| (523759) 2014 WK509 | 584[14] | ✗ | 40.1–61.6 AU | Extended | |
| (523692) 2014 EZ51 | 575[20] | ✗ | 40.4–64.4 AU | Extended | |
| 2014 FC69 | 533[14] | ✗ | 40.1–104.2 AU | Extended | |
| (145451) 2005 RM43 | 524[14] | ✗ | 35.1–89.6 AU | Normal | |
| (690420) 2014 FC72 | 502[14] | ✗ | 51.7–76.1 AU | Extended |
References & Footnotes[]
- ↑ 1.0 1.1 The Scattered Disk as the Source of the Jupiter Family Comets, written by Kathryn Volk and Renu Malhotra, 2008.
- ↑ Another Ring of Objects Might Exist in the Outer Solar System, written by Jonathan O’Callaghan, 2024.
- ↑ Oort cloud Ecology, written by Simon Portegies Zwart et al., 2020.
- ↑ Scattered Disk Objects (SDOs), written by Janine Ungvarsky, 2022.
- ↑ Mystery orbits in outermost reaches of solar system not caused by 'Planet Nine', written by the University of Cambridge, 2019.
- ↑ On the existence of a comet belt beyond Neptune, written by Julio A. Fernández, 1980.
- ↑ SCATTERED KUIPER BELT OBJECTS (SKBOs), author unknown, 2009.
- ↑ The Solar System Beyond The Planets, written by Audrey Delsanti and David Jewitt, 2006.
- ↑ Values are rounded to the nearest tenth.
- ↑ Size, density, albedo and atmosphere limit of dwarf planet Eris from a stellar occultation, written by B. Sicardy et al., 2011.
- ↑ The mass and density of the dwarf planet (225088) 2007 OR10, written by Csaba Kiss et al., 2019.
- ↑ “TNOs are Cool”: A survey of the trans-Neptunian region, written by A. Pál et al., 2012.
- ↑ Based on the minor planet's absolute magnitude and albedo.
- ↑ 14.0 14.1 14.2 14.3 14.4 14.5 List of known trans-Neptunian objects, compiled by William Robert Johnson.
- ↑ A second Sedna! What does it mean?, written by Emily Lakdawalla, 2014.
- ↑ DISCOVERY OF A LOW-ECCENTRICITY, HIGH-INCLINATION KUIPER BELT OBJECT AT 58 AU, written by R. L. Allen et al., 2006.
- ↑ Results from a triple chord stellar occultation and far-infrared photometry of the trans-Neptunian object (229762) 2007 UK126, written by K. Schindler et al., 2017.
- ↑ Orbit Fit and Astrometric record for 229762, compiled by Marc W. Buie, 2012.
- ↑ Pushing the Limits: K2 Observations of the Trans-Neptunian Objects 2002 GV31 and (278361) 2007 JJ43, written by A. Pál et al., 2015.
- ↑ (523692) 2014 EZ51, 2019 February 25 occultation, 2019.
| Small Solar System Bodies including comets | ||
|---|---|---|
| Cis-Neptunian | NEO | ꞌAylóꞌchaxnim • Atrias • Apollos • Arjunas • Amors • Venus Trojan • Earth Trojans • Mars Trojans • Quasi-Satellites |
| Main Belt/Jupiter Trojans | Asteroids • Various Collisional Families • Ceres/Vesta Trojans • Hilda • Jupiter Trojans • Quasi-Satellites | |
| Distant/Centaur | Centaur • Damocloid • Saturn Trojan • Uranus Trojans • Neptune Trojans | |
| TNO | Kuiper Belt/KBO | Classical (Cold • Hot) • Resonant (Plutino • Twotino) |
| Scattered disc/SDO | Resonant | |
| ETNO | ESDO | |
| EDDO | Sednoid → Oort Cloud Objects | |
| Comets | NEC • Sungrazing/Kreutz Sungrazing • Remnant • Extinct • Lost • Jupiter • Quasi-Hilda • Halley-type | |