List of Halley-type comets

Last updated

The following is a list of Halley-type comets (HTCs), which are periodic comets with an orbital period between 20 and 200 years, often appearing only once or twice within one's lifetime. The majority come from between the orbits of Saturn and Neptune. Due to the nature of their orbits, they can be perturbed by the giant planets and sent into orbits too far from the Sun to outgas, and vice versa. Minor planets in comet-like orbits similar to HTCs that never come close enough to the Sun to outgas are called centaurs. HTCs are named after the first discovered member, and the first discovered periodic comet, Halley's Comet, which orbits the Sun in about 75 years, and passing as far as the orbit of Neptune.


Most of the comets that have a period between 20 and 200 years (making them HTCs based on the classical definition) are actually officially classified as either Jupiter-family comets (JFCs) or Chiron-type comets (CTCs), based on their Jupiter Tisserand's parameter (TJupiter). Although JFCs are classically defined by (P < 20 y), they're officially defined by (2 < TJupiter < 3). CTCs, on the other hand, are officially defined by (TJupiter > 3; a > aJupiter). Since they do not include any period-related constraints, some of the 20–200 year-period comets unfortunately match one of the classifications, making comet classifications even more vague.

Numbered HTCs

For the 14 numbered HTCs, see the list of numbered comets, where they are labelled "HTC" in column "class".

Unnumbered HTCs

This list contains only Halley-type comets which are not numbered yet because they have been observed only once. Comets that belong to a different comet classification based on its Jupiter Tisserand parameter are given its alternative classification next to the comets' name.

Comet designation Comet name Eccentricity Semimajor axis (AU) Period (years) Inclination (°) Perihelion distance (AU) Absolute magnitude Last perihelion Next perihelionRef
C/1917 F1 Mellish 0.99312127.647332514532.68280.1901861917/04/112062 MPC  · JPL
C/1921 H1Dubiago0.8682222.111.10081921/05/042031 MPC  · JPL
C/1937 D1Wilk0.98109832.744524418726.02050.6189371937/02/212124 MPC  · JPL
C/1942 EA Väisälä 0.93363919.395111685.437.99611.2870791942/02/152027/07/10 MPC  · JPL
C/1984 A1 Bradfield 10.952428.5152.351.80051.357519.61983/12/272136/04/01 MPC  · JPL
C/1989 A3Bradfield0.97770818.85381.983.06720.4202711988/12/052070/11/01 MPC  · JPL
C/1991 L3 Levy 0.92881113.801851.2819.190310.9825458.81991/07/082042/10/19 MPC  · JPL
C/1998 G1 LINEAR 0.823712.09942.08109.7142.133310.81998/11/162040/12/15 MPC  · JPL
C/1998 Y1LINEAR0.923922.95611028.10821.74699141998/11/212108/11/15 MPC  · JPL
C/1999 E1 Li 0.7601116.34166.0646.881083.920028.31998/01/312065/02/21 MPC  · JPL
C/1999 G1 LINEAR 0.85628.114976.554.04881998/08/012150 MPC  · JPL
C/1999 K4LINEAR0.922070120.81.44218.51999/05/162069/06/08 MPC  · JPL
C/1999 S3LINEAR0.8999518.9482.4370.56071.8949394.91999/11/092081/04/04 MPC  · JPL
C/1999 XS87LINEAR (*JFC)0.8405717.38672.514.84642.771810.91999/08/062072/02/04 MPC  · JPL
C/2000 D2LINEAR0.86717.272156.9922.297513.72000/03/082072 MPC  · JPL
C/2000 G2LINEAR0.8051452170.47852.71612.82000/02/052052 MPC  · JPL
C/2000 S3 LONEOS (*JFC)0.772311.6939.9725.1642.66226.42000/07/162040/07/10 MPC  · JPL
C/2001 M10 NEAT (*JFC)0.8010726.657137.6328.083495.302759.42001/06/212139/02/01 MPC  · JPL
C/2001 OG108 LONEOS 0.925259513.348.580.245050.994047913.22002/03/152050/09/13 MPC  · JPL
P/2001 Q6 NEAT 0.823867.994622.6156.85531.40817913.32001/11/092024/06/20 MPC  · JPL
C/2001 W2 BATTeRS 0.9413617.92575.89115.91311.05106512.12001/12/232077/11/15 MPC  · JPL
C/2002 A1 LINEAR (*JFC)0.7228116.99270.0414.033934.709968.62001/11/262071/12/11 MPC  · JPL
C/2002 A2LINEAR (*JFC)0.7248217.10370.7414.03864.706597.52001/12/052072/09/01 MPC  · JPL
C/2002 B1LINEAR0.771029.918331.2451.02142.271136.32002/04/202032/06/17 MPC  · JPL
C/2002 CE10LINEAR0.7914869.8159530.75145.45872.046759310.82003/06/222034/03/23 MPC  · JPL
C/2002 K4 NEAT 0.8423217.53273.4194.06322.7645311.42002/07/122075/12/01 MPC  · JPL
P/2002 T6NEAT–LINEAR (*JFC)0.5573487.651921.1711.009273.3871035.92003/06/272024/08/28 MPC  · JPL
C/2003 E1NEAT (*JFC)0.7635913.726350.8633.537853.24500410.62004/02/132054/12/24 MPC  · JPL
C/2003 F1 LINEAR 0.8060520.66493.9370.22164.0078068.32003/06/282097/06/02 MPC  · JPL
P/2003 QX29 NEAT (*JFC)0.47188.025522.7411.39654.2396.12002/10/262025/07/21 MPC  · JPL
C/2003 R1 LINEAR 0.8933119.787.44149.195632.1018812.72003/06/292090/12/15 MPC  · JPL
C/2003 U1LINEAR0.921622.9109.6164.47451.7957215.22003/11/032113 MPC  · JPL
C/2003 W1LINEAR0.9342925.15126.178.07561.6524113.52003/11/092130 MPC  · JPL
P/2004 A1 LONEOS (*JFC)0.308417.8985322.210.575685.462544102004/08/262026/11/07 MPC  · JPL
C/2004 C1 Larsen (*JFC)0.623111.56639.3328.9184.3594102003/03/192042/09/01 MPC  · JPL
P/2004 DO29 SpacewatchLINEAR (*JFC)0.451517.465520.414.53584.0947510.32004/10/112025/03/06 MPC  · JPL
P/2004 V5-ALINEAR–Hill (*JFC)0.4452177.9505922.4219.3581364.4108538.82005/02/282027/07/31 MPC  · JPL
P/2004 V5-BLINEAR–Hill (*JFC)0.4452337.9509222.4219.358224.410919.22005/03/012027/08/02 MPC  · JPL
C/2005 N5 Catalina 0.9432728.687153.6521.378791.627412.92005/08/222159/01/01 MPC  · JPL
C/2005 O2 Christensen 0.8593923.707115.43148.892043.333585.22005/09/082121/02/15 MPC  · JPL
P/2005 S2 Skiff (*CTC)0.19677.96522.483.1416.3987.92006/06/302028/12/22 MPC  · JPL
P/2005 T3Read (*CTC)0.1747.50920.586.266.2029.22006/01/132026/08/15 MPC  · JPL
P/2005 T4 SWAN 0.939.328.4160.03620.64939915.42005/10/102034 MPC  · JPL
C/2005 W2Christensen (*JFC)0.8244618.97982.6811.264033.3316210.82006/03/272096/12/01 MPC  · JPL
C/2006 F2Christensen (*JFC)0.6513812.32443.2720.5114.296510.62006/05/302049/09/06 MPC  · JPL
P/2006 HR30 Siding Spring 0.84311847.8175421.8631.8844991.226427711.72007/01/022028/11/12 MPC  · JPL
C/2006 U7Gibbs (*JFC)0.630911.9941.5157.7624.42511.62007/03/282048/10/01 MPC  · JPL
C/2007 S2 Lemmon (*JFC)0.55705612.547744.4516.863055.55793192008/09/142053/02/25 MPC  · JPL
C/2008 E1 Catalina (*JFC)0.5481510.68734.9435.037694.828919.12008/08/112043/07/31 MPC  · JPL
P/2008 O3 Boattini (*JFC)0.69498.18623.4232.26992.49735.12008/06/032031/11/03 MPC  · JPL
C/2008 R3 LINEAR 0.8964118.42879.1143.237931.90903513.52008/11/222088/01/01 MPC  · JPL
P/2008 Y3 McNaught (*JFC)0.447668.028122.7538.813184.4342418.72009/01/112031/10/12 MPC  · JPL
P/2009 O3 Hill (*JFC)0.686887.824421.8916.21762.44999122009/05/182031/04/08 MPC  · JPL
P/2009 Q5 McNaught (*JFC)0.6090617.465420.440.90482.9185110.52009/09/082030/02/02 MPC  · JPL
P/2009 T2 La Sagra (*JFC)0.7689917.59620.9428.106391.7547514.22010/01/122030/12/21 MPC  · JPL
P/2010 E2Jarnac (*JFC)0.722378.640225.415.4372.3987414.42010/04/072035/08/31 MPC  · JPL
C/2010 E5 Scotti (*JFC)0.8427424.73122.9618.91023.88846.12009/11/212132/11/01 MPC  · JPL
P/2010 J3 McMillan (*JFC)0.726828.987126.9413.255072.4551111.62010/08/232037/08/01 MPC  · JPL
P/2010 JC81 WISE 0.777358.1330723.1938.690251.810831110.32011/04/262034/07/04 MPC  · JPL
C/2010 L5WISE0.9048.223.6147.0520.790917.42010/04/232033 MPC  · JPL
C/2011 J3 LINEAR 0.925819.5686.5114.71241.45113.12011/01/242097 MPC  · JPL
P/2011 JB15 SpacewatchBoattini 0.318747.36682019.141275.018715.52012/01/212032/01/21 MPC  · JPL
C/2011 L1 McNaught 0.7967811.03436.6665.5122.2423710.62010/12/182047/08/15 MPC  · JPL
P/2011 P1McNaught (*JFC)0.35987.74121.546.17414.95568.22010/07/222032/02/04 MPC  · JPL
C/2011 P2 PANSTARRS (*CTC)0.369829.756230.478.989646.14816.72010/09/132041/03/04 MPC  · JPL
P/2011 S1Gibbs (*CTC)0.203058.654525.462.67926.89725.52014/08/202040/02/04 MPC  · JPL
C/2011 S2 Kowalski 0.931616.30465.8317.572531.11511814.82011/10/262077/08/25 MPC  · JPL
C/2011 Y3 Boattini (*JFC)0.70511.8540.8226.5173.497811.72011/08/222052/06/17 MPC  · JPL
C/2012 BJ98 Lemmon [1] (*JFC)0.8736517.06870.522.63692.1565778.12012/09/202083/03/29 MPC  · JPL
P/2012 C3 PANSTARRS (*JFC)0.62649.730.29.193.62513.52011/10/052042 MPC  · JPL
C/2012 H2 McNaught 0.893616.1464.992.83551.7167815.72012/05/032077 MPC  · JPL
P/2012 NJ La Sagra 0.8480628.502724.7984.375461.291890113.12012/06/132037/03/28 MPC  · JPL
C/2012 Q1 Kowalski (*JFC)0.6372226.138133.6345.1819.482224.72012/02/092145/10/01 MPC  · JPL
C/2012 T6Kowalski0.8763414.35454.3833.27551.7750915.72012/08/262067/01/15 MPC  · JPL
C/2012 X2 PANSTARRS (*JFC)0.7705220.6994.1234.123894.748169.62013/03/312107/05/14 MPC  · JPL
C/2012 Y3 McNaught 0.9399329.38159.373.23181.7648210.42012/08/252172 MPC  · JPL
C/2013 C2 Tenagra (*CTC)0.429316.00164.0121.344269.13214.42015/08/282080/09/01 MPC  · JPL
C/2013 D1 Holvorcem (*JFC)0.7808811.22737.6210.093562.4601313.52013/04/132050/11/25 MPC  · JPL
P/2013 N3 PANSTARRS (*JFC)0.59247.43120.262.170413.02896.62014/02/112034/05/17 MPC  · JPL
P/2013 P1PANSTARRS (*JFC)0.60538.58825.1718.7023.390211.62013/02/262038/04/29 MPC  · JPL
C/2013 P4PANSTARRS (*CTC)0.5963614.78356.844.264255.967035.12014/08/122071/06/15 MPC  · JPL
C/2013 U1 Catalina (*JFC)0.797111.9241.1723.94152.418813.92013/11/182055/01/01 MPC  · JPL
C/2013 V3 Nevsky 0.8909712.71845.3632.13451.38669315.22013/10/292059/03/09 MPC  · JPL
C/2013 W2 PANSTARRS (*JFC)0.56110.1332.234.54364.4485.82015/01/082047/03/15 MPC  · JPL
C/2014 F3 SheppardTrujillo (*JFC)0.6516.3666.485.76.12021/04/172087 MPC  · JPL
C/2014 HU195Valdes–TOTAS (*JFC)0.7658021.867102.255.822275.1211314.62015/05/182117/08/14 MPC  · JPL
C/2014 J1 Catalina 0.8028.6425.4159.6961.708516.82014/06/202039 MPC  · JPL
P/2014 L3 Hill (*JFC)0.773098.170623.366.2641.8539613.72014/06/282037/11/06 MPC  · JPL
P/2014 O3 PANSTARRS (*JFC)0.38477.54420.727.814.64210.42014/04/162035/01/04 MPC  · JPL
C/2014 Q3 Borisov 0.9420728.436151.6489.948881.6474088.82014/11/192166/07/10 MPC  · JPL
C/2014 TG64 Catalina (*JFC)0.782414.8922.2833.23913.246.42014/05/262072 MPC  · JPL
C/2014 W7Christensen0.86911.33898.3141.488116.32014/12/312052 MPC  · JPL
C/2014 W9 PANSTARRS 0.857711.1637.2810.63021.587415.52015/02/152052/04/01 MPC  · JPL
C/2014 W11PANSTARRS (*JFC)0.6502559.798030.6712.706793.4268058.82015/06/172036/04/16 MPC  · JPL
C/2015 A1PANSTARRS0.90081620.11990.2480.365761.9955056.92015/03/132105/06/09 MPC  · JPL
P/2015 A3PANSTARRS0.857.621172.511.15420.22015/02/222036 MPC  · JPL
P/2015 B1PANSTARRS (*JFC)0.382509.677230.1018.0275.975678.72015/09/192045/10/26 MPC  · JPL
P/2015 B4 Lemmon–PANSTARRS (*JFC)0.568948.712125.721.742623.7554011.72015/02/172030/12/04 MPC  · JPL
C/2015 D2PANSTARRS (*JFC)0.5682612.98546.7931.83395.60606.32013/09/272060/07/13 MPC  · JPL
C/2015 D5 Kowalski (*JFC)0.49969.14527.6620.39904.5766.02014/04/162041/12/12 MPC  · JPL
C/2015 F5 SWANXingMing 0.9776415.4760.9149.25900.34599517.62015/03/282075/02/01 MPC  · JPL
C/2015 GX PANSTARRS 0.87819816.188365.1390.254541.97175314.42015/08/262080/10/09 MPC  · JPL
C/2015 H1Bressi0.9407832.53185.5140.655581.926366.62015/03/282200/10/07 MPC  · JPL
P/2015 Q2Pimentel0.75447.40720.16146.20221.8191215.32015/09/102035/11/06 MPC  · JPL
C/2015 T5 SheppardTholen (*CTC)0.666127.97147.911.04839.33837.72016/01/242164 MPC  · JPL
C/2015 V4 PANSTARRS 0.7056718.55079.8960.75135.459728.72016/08/272096/07/19 MPC  · JPL
C/2015 X2PANSTARRS0.879115.7562.572.4581.9045616.12015/12/202078/06/25 MPC  · JPL
C/2015 X4 Elenin (*JFC)0.81280718.134577.2329.504913.3946610.12015/11/032093/02/14 MPC  · JPL
C/2015 X8 NEOWISE 0.939319.686.9155.28171.190314.12015/10/232099/09/13 MPC  · JPL
C/2015 YG1 NEOWISE 0.8792417.16971.1457.33602.0734112.32015/09/282086/11/17 MPC  · JPL
P/2016 A3 PANSTARRS (*JFC)0.37787.697921.368.59294.78955.42017/04/132038/08/22 MPC  · JPL
C/2016 Q4 Kowalski (*CTC)0.578116.7968.87.25677.0847.02018/01/282086 MPC  · JPL
C/2016 S1 PANSTARRS 0.708878.28523.8594.68982.411937.52017/03/162041/01/20 MPC  · JPL
P/2016 WM48Lemmon0.78678.195423.46117.54761.748016.82017/02/262040 MPC  · JPL
C/2017 C1 NEOWISE 0.926369720.783292.0865.731541.501722017/01/192109 MPC  · JPL
P/2017 D4 PANSTARRS (*JFC)0.628987.42420.2310.33962.754512.72016/09/062036/11/29 MPC  · JPL
C/2017 E2 Tsuchinshan 0.8908521.5567100.0979.16862.3529511.32016/05/122116/06/14 MPC  · JPL
P/2017 G1 PANSTARRS (*JFC)0.661347.738721.533.5342.62113.12016/05/142037/11/23 MPC  · JPL
P/2017 G2PANSTARRS0.650318.139423.2247.906252.84612.92017/06/132040/09/02 MPC  · JPL
C/2017 K4 ATLAS (*JFC)0.9057128.0883148.8716.678222.648247.22018/01/082167 MPC  · JPL
P/2017 P1 PANSTARRS (*JFC)0.30887.8656622.067.70135.4366510.12018/06/182040/07/10 MPC  · JPL
C/2017 S2PANSTARRS (*JFC)0.8240620.540093.0912.677233.61313.22017/08/282110 MPC  · JPL
C/2017 U5PANSTARRS (*JFC)0.7445716.93969.7218.95664.3267611.82017/12/192087/09/07 MPC  · JPL
C/2017 W2 Leonard 0.711513.717650.8198.18313.95810.92017/11/022068 MPC  · JPL
P/2017 W3Gibbs (*JFC)0.50397.73421.5118.3173.837310.52018/02/252039/08/30 MPC  · JPL
C/2017 X1 PANSTARRS (*JFC)0.851131.3092175.1931.31064.66249.62018/06/142193 MPC  · JPL
P/2017 Y3 Leonard 0.87039.83830.8627.58591.275313.62018/02/112049 MPC  · JPL
C/2018 A1 PANSTARRS 0.906125.8169131.1853.62132.423313.12017/10/202148 MPC  · JPL
C/2018 A6Gibbs0.827317.43472.8077.4543.0118.92019/07/082092 MPC  · JPL
C/2018 DO4 Lemmon 0.906929.847131.40160.4752.40613.72019/08/182151 MPC  · JPL
C/2018 K1Weiland0.937129.890163.42164.1931.87911.92018/04/062182 MPC  · JPL
C/2018 M1 CSS 0.940922.087103.8137.2651.30415.92018/07/102122 MPC  · JPL
C/2018 O1 ATLAS 0.94427.864147.09154.0411.55812.62018/08/312165 MPC  · JPL
C/2018 R5 Lemmon 0.841822.8947109.55103.763.621362019/01/092128 MPC  · JPL
C/2018 V2 ATLAS 0.903425.616129.65159.1112.47514.52018/11/262148 MPC  · JPL
C/2018 W1 CSS 0.93821.779101.6483.2731.3615.6482019/05/112120 MPC  · JPL
C/2018 X3 PANSTARRS 0.78312.4168643.7543.3682.6988715.52018/12/302062 MPC  · JPL
P/2018 Y2Africano (*JFC)0.48787.54320.7211.488863.8635112018/12/132039 MPC  · JPL
C/2019 A5 PANSTARRS 0.708021.6608100.8167.53106.32429.42019/06/092119 MPC  · JPL
C/2019 L1 PANSTARRS (*JFC)0.70659.847430.909.9932.8898613.62019/08/112050 MPC  · JPL
C/2019 L2 NEOWISE 0.937025.72130.48152.191.62210.32019/04/022149 MPC  · JPL
C/2019 LB7Kleyna0.929335.1204208.14164.232.48318.12019/03/272227 MPC  · JPL
C/2019 T5ATLAS0.80928.01422.6933.421.528914.92019/08/012042 MPC  · JPL
P/2019 V2Groeller (*JFC)0.3337.52320.6311.85.01839.82020/10/212041 MPC  · JPL
C/2019 Y4-D ATLAS 0.988823.187111.6544.020.258914.52020/05/312132 MPC  · JPL
C/2019 Y4-E ATLAS 0.98719.77587.9445.0850.252516.32020/05/312108 MPC  · JPL
C/2020 Q2 PANSTARRS (*JFC)0.505510.923136.103.3105.40210.92020/02/072056 MPC  · JPL
C/2020 S2 PANSTARRS 0.827510.179332.4822.39781.75616.32020/12/212052 MPC  · JPL
P/2020 V3 PANSTARRS (*JFC)0.25478.3624.1723.0356.238.62021/02/072045 MPC  · JPL
P/2020 V4Rankin (*JFC)0.44849.333628.5214.2455.156.92021/07/182050 MPC  · JPL
P/2021 C2 PANSTARRS (*JFC)0.48749.540829.4721.9274.89011.42021/02/242050 MPC  · JPL
C/2021 J1 Maury-Attard0.933826.296134.8592.7101.7413.42021/02/192155 MPC  · JPL
P/2021 J3 ATLAS (*JFC)0.45078.93126.6914.5734.8906.92019/07/032046 MPC  · JPL
C/2021 K1 ATLAS (*JFC)0.804012.74545.5016.2762.4986.22021/05/042066 MPC  · JPL
P/2021 R1 PANSTARRS (*JFC)0.42298.46724.645.5204.8867.42021/12/162046 MPC  · JPL
P/2021 R8Sheppard0.29403.0185.242.2032.13118.62021/10/072026 MPC  · JPL
P/2021 U1Wierzchos0.71278.51124.8330.5602.44516.12021/09/302046 MPC  · JPL
P/2021 V2Fuls (*JFC)0.61309.03427.1512.6963.5007.02023/01/212050 MPC  · JPL

See also

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A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.

Centaur (small Solar System body) Type of solar system object

In planetary astronomy, a centaur is a small Solar System body with either a perihelion or a semi-major axis between those of the outer planets. Centaurs generally have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets; almost all their orbits have dynamic lifetimes of only a few million years, but there is one known centaur, 514107 Kaʻepaokaʻawela, which may be in a stable orbit. Centaurs typically exhibit the characteristics of both asteroids and comets. They are named after the mythological centaurs that were a mixture of horse and human. Observational bias toward large objects makes determination of the total centaur population difficult. Estimates for the number of centaurs in the Solar System more than 1 km in diameter range from as low as 44,000 to more than 10,000,000.

12P/Pons–Brooks is a periodic comet with an orbital period of 71 years. It fits the classical definition of a Halley-type comet with. The next perihelion passage is 20–21 April 2024, with closest approach to Earth being 1.54 AU (230 million km) on 2 June 2024.

Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-type or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Jupiter Tisserand invariant (TJ) of 2 or less, while Akimasa Nakamura defines this group with the following orbital elements:

Orbital eccentricity Amount by which an orbit deviates from a perfect circle

In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the galaxy.

Scattered disc Collection of bodies in the extreme Solar System

The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small solar system bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5×109 km; 2.8×109 mi). These extreme orbits are thought to be the result of gravitational "scattering" by the gas giants, and the objects continue to be subject to perturbation by the planet Neptune.

167P/CINEOS (P/2004 PY42) is a large periodic comet and active, grey centaur, approximately 66 kilometers (41 miles) in diameter, orbiting the Sun outside the orbit of Saturn in the Solar System. It was discovered on August 10, 2004, by astronomers with the CINEOS survey at Gran Sasso in Italy. It is one of only a handful known Chiron-type comets.

Tisserand's parameter is a value calculated from several orbital elements of a relatively small object and a larger "perturbing body". It is used to distinguish different kinds of orbits. The term is named after French astronomer Félix Tisserand, and applies to restricted three-body problems in which the three objects all differ greatly in mass.

38P/Stephan–Oterma is a periodic comet with an orbital period of 38 years. It fits the classical definition of a Halley-type comet with. It was discovered in January 1867, by Jérôme Eugène Coggia at Marseilles Observatory, France.

122P/de Vico is a periodic comet with an orbital period of 74 years. It fits the classical definition of a Halley-type comet with. It was discovered by Francesco de Vico in Rome on February 20, 1846.

C/1980 E1 (Bowell)

C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. Since its discovery only 1I/ʻOumuamua and 2I/Borisov have been identified with a faster such trajectory.

2005 VX3 is trans-Neptunian object and retrograde damocloid on a highly eccentric, cometary-like orbit. It was first observed on 1 November 2005, by astronomers with the Mount Lemmon Survey at the Mount Lemmon Observatory in Arizona, United States. The unusual object measures approximately 7 kilometers (4 miles) in diameter. It has the 3rd largest known heliocentric semi-major axis and aphelion. Additionally its perihelion lies within the orbit of Jupiter, which means it also has the largest orbital eccentricity of any known minor planet.

2002 RN109 is a trans-Neptunian object and damocloid on a highly eccentric, cometary-like orbit. It was first observed on 6 September 2002, by astronomers with the Lincoln Near-Earth Asteroid Research at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States. The unusual object measures approximately 4 kilometers (2 miles) in diameter. It has the second highest orbital eccentricity of any known minor planet, after 2005 VX3.

In planetary science, the term unusual minor planet, or unusual object, is used for a minor planet that possesses an unusual physical or orbital characteristic. For the Minor Planet Center (MPC), which operates under the auspices of the International Astronomical Union, any non-classical main-belt asteroid, which account for the vast majority of all minor planets, is an unusual minor planet. These include the near-Earth objects and Trojans as well as the distant minor planets such as centaurs and trans-Neptunian objects. In a narrower sense, the term is used for a group of bodies – including main-belt asteroids, Mars-crossers, centaurs and otherwise non-classifiable minor planets – that show a high orbital eccentricity, typically above 0.5 and/or a perihelion of less than 6 AU. Similarly, an unusual asteroid (UA) is an inner Solar System object with a high eccentricity and/or inclination but with a perihelion larger than 1.3 AU, which does exclude the near-Earth objects.

A Chiron-type comet (CTC) is a member of a small family of comets defined as having a semi-major axis larger than that of Jupiter (5.2 AU) and a Tisserand's parameter with respect to Jupiter (TJupiter) of more than 3.


  1. Yoshida, Seiichi. "C/2012 BJ98 (Lemmon)". Retrieved 23 July 2014.