120P/Mueller
Periodic comet
title: "120P/Mueller" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["periodic-comets", "jupiter-family-comets", "numbered-comets", "discoveries-by-jean-mueller", "discoveries-by-the-palomar-observatory", "comets-in-2013", "comets-in-2021", "astronomical-objects-discovered-in-1987"] description: "Periodic comet" topic_path: "general/periodic-comets" source: "https://en.wikipedia.org/wiki/120P/Mueller" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Periodic comet ::
::data[format=table title="Infobox comet"]
| Field | Value |
|---|---|
| name | 120P/Mueller |
| discovery_ref | |
| discoverer | Jean E. Mueller |
| discovery_site | Palomar Observatory |
| discovery_date | 18 October 1987 |
| mpc_name | P/1987 U2 |
| P/1995 O2 | |
| designations | Mueller 1 |
| 1987 XXXI, 1987a1 | |
| orbit_ref | |
| epoch | 6 September 2007 (JD 2454349.5) |
| observation_arc | 34.14 years |
| obs | 147 |
| perihelion | 2.744 AU |
| aphelion | 5.527 AU |
| semimajor | 4.136 AU |
| eccentricity | 0.33654 |
| period | 8.412 years |
| inclination | 8.791° |
| asc_node | 4.443° |
| arg_peri | 30.008° |
| mean | 125.57° |
| tjup | 2.917 |
| Earth_moid | 1.754 AU |
| Jupiter_moid | 0.265 AU |
| physical_ref | |
| mean_radius | 0.77 km |
| M1 | 6.6 |
| M2 | 16.4 |
| last_p | 7 May 2021 |
| next_p | 5 April 2029 |
| :: |
| name = 120P/Mueller | image = | discovery_ref = | discoverer = Jean E. Mueller | discovery_site = Palomar Observatory | discovery_date = 18 October 1987 | mpc_name = P/1987 U2 P/1995 O2 | designations = Mueller 1 1987 XXXI, 1987a1 | orbit_ref = | epoch = 6 September 2007 (JD 2454349.5) | observation_arc = 34.14 years | obs = 147 | perihelion = 2.744 AU | aphelion = 5.527 AU | semimajor = 4.136 AU | eccentricity = 0.33654 | period = 8.412 years | inclination = 8.791° | asc_node = 4.443° | arg_peri = 30.008° | mean = 125.57° | tjup = 2.917 | Earth_moid = 1.754 AU | Jupiter_moid = 0.265 AU | physical_ref = | mean_radius = 0.77 km | M1 = 6.6 | M2 = 16.4 | last_p = 7 May 2021 | next_p = 5 April 2029
120P/Mueller, also known as Mueller 1, is a Jupiter-family comet with an 8.4-year orbit around the Sun. It is one of 15 comets discovered by American astronomer, Jean Mueller.
Observational history
Jean Mueller first spotted the comet on photographic plates exposed from the Palomar Observatory on the night of 18 October 1987. She described the new comet as a diffuse 17th-magnitude object within the constellation Pisces. A condensation and an apparent tail about 20–30 arcseconds in length towards the south-southwest was also noted. Orbital calculations using follow-up observations until 27 October 1987 helped Daniel W. E. Green to determine Mueller's comet as periodic, at the time having an orbital period of roughly 8.21 years.
James V. Scotti recovered the comet from the Kitt Peak Observatory on 30 July 1995 as P/1995 O1. It was a 22nd-magnitude object at the time of its recovery. The comet was observed from every subsequent apparition since. It most recently came to perihelion in May 2021 and underwent a 1.4 magnitude outburst in August 2021.
Physical characteristics
Initial estimates of the size of its nucleus in 2004 was approximately 3.0 km in diameter. Optical photometry obtained in 2007 revised this to half of the previous estimate, currently about 1.54 km in diameter.
Notes
References
| title= Horizons Batch for 120P/Mueller 1 on 2029-Apr-05 | publisher= JPL Horizons | type= Perihelion occurs when rdot flips from negative to positive | url= https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27120P%27&START_TIME=%272029-03-27%27&STOP_TIME=%272029-04-15%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27 | access-date= 2021-09-13 }} (JPL#20/Soln.date: 2021-Apr-15)
| author1= J. E. Mueller | author2= N. Reid | author3= A. Maury | editor1= D. W. Green | title= Comet Mueller (1987a1) | url= http://www.cbat.eps.harvard.edu/iauc/04400/04472.html | journal= IAU Circular | date= 1987-10-19 | volume= 4472 | issue= 2 | bibcode= 1987IAUC.4472....2M }}
| author1= E. M. Shoemaker | author2= C. S. Shoemaker | author3= H. Holt | display-authors= etal | editor1= D. W. Green | title= Periodic Comet Mueller (1987a1) | url= http://www.cbat.eps.harvard.edu/iauc/04400/04480.html | journal= IAU Circular | date= 1987-10-27 | volume= 4480 | issue= 1 | bibcode= 1987IAUC.4480....1S }}
| author1= J. V. Scotti | author2= S. Nakano | editor1= B. G. Marsden | title= Comet P/1995 O1 (Mueller) | url= http://www.cbat.eps.harvard.edu/iauc/06100/06199.html | journal= IAU Circular | date= 1995-08-03 | volume= 6199 | issue= 1 | bibcode= 1995IAUC.6199....1S }}
| title= 120P/Mueller 1 – JPL Small-Body Database Lookup | url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=120P | website= ssd.jpl.nasa.gov | publisher= Jet Propulsion Laboratory | access-date= 2025-12-05 }}
| author1= M. S. P. Kelley | title= Small Apparent Outburst of Comet 120P/Mueller 1 | url= https://www.astronomerstelegram.org/?read=14876 | journal= The Astronomer's Telegram | volume= 14876 | pages= 1 | bibcode= 2021ATel14876....1K }}
| author1= G. W. Kronk | author2= M. Meyer | author3= D. A. J. Seargent | title= Cometography: A Catalog of Comets | volume= 6: 1983–1994 | date= 2017 | publisher= Cambridge University Press | location= Cambridge | isbn= 978-0-521-87216-4 | pages= 320–322 }}
| author1= P. L. Lamy | author2= I. Toth | author3= Y. R. Fernández | author4= H. A. Weaver | title= Comets II | chapter= The Sizes, Shapes, Albedos, and Colors of Cometary Nuclei | chapter-url= https://physics.ucf.edu/~yfernandez/papers/comets2chapter/comets2reprint.pdf | year= 2004 | pages= 223–264 | publisher= University of Arizona Press | doi= 10.2307/j.ctv1v7zdq5.22 | bibcode= 2004come.book..223L | jstor= j.ctv1v7zdq5.22 | isbn= 978-0-8165-2450-1 }}
| title= 120P/Mueller Orbit | url= http://www.minorplanetcenter.net/db_search/show_object?object_id=120P | publisher= Minor Planet Center | access-date= 2014-06-17 }}
| author1= C. S. Snodgrass | author2= S. C. Lowry | author3= A. Fitzsimmons | title= Optical observations of 23 distant Jupiter Family Comets, including 36P/Whipple at multiple phase angles | url= https://academic.oup.com/mnras/article-pdf/385/2/737/18228737/mnras0385-0737.pdf | journal= Monthly Notices of the Royal Astronomical Society | year= 2007 | volume= 385 | issue= 2 | pages= 737–756 | bibcode= 2008MNRAS.385..737S | arxiv= 0712.4204 | s2cid= 55536237 | doi= 10.1111/j.1365-2966.2008.12900.x | doi-access= free }}
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