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{{Infobox planet
| minorplanet=yes
| background=#D6D6D6
| name=120 Lachesis
| discoverer=Alphonse Borrelly
| discovered=10 April 1872
| mpc_name=(120) Lachesis
| alt_names=
| pronounced={{IPAc-en|ˈ|l|æ|k|ᵻ|s|ɪ|s}}
| named_after=Lachesis
| mp_category=Main belt
| epoch=31 July 2016 (JD 2457600.5)
| orbit_ref=
| semimajor={{Convert|3.11767|AU|Gm|abbr=on}}
| perihelion={{Convert|2.95390|AU|Gm|abbr=on}}
| aphelion={{Convert|3.2814|AU|Gm|abbr=on|lk=on}}
| eccentricity=0.052528
| period=5.50 yr (2010.7 d)
| inclination=6.9643°
| asc_node=341.193°
| arg_peri=232.822°
| mean_anomaly=56.2095°
| avg_speed=16.86 km/s
| dimensions={{val|174.10|2.9|ul=km}} {{small|(IRAS)}}
| mass=5.5{{E|18}} kg
| density=
| surface_grav=0.0487 m/s²
| escape_velocity=0.0920 km/s
| rotation={{Convert|46.551|h|d|abbr=on|lk=on}}[[4]]
| spectral_type=C[5]
| abs_magnitude=7.75
| albedo={{val|0.0463|0.002}}
| single_temperature=~158 K
| mean_motion={{Deg2DMS|0.179044|sup=ms}} / day
| observation_arc=143.70 yr (52485 d)
| uncertainty=0
| moid={{Convert|1.95464|AU|Gm|abbr=on}}
| jupiter_moid={{Convert|1.72275|AU|Gm|abbr=on}}
| tisserand=3.204
}}Lachesis (minor planet designation: 120 Lachesis) is a large main-belt asteroid. It was discovered by French astronomer Alphonse Borrelly on April 10, 1872, and independently by German-American astronomer Christian Heinrich Friedrich Peters on April 11, 1872, then named after Lachesis, one of the Moirai, or Fates, in Greek mythology.[8] A Lachesean occultation of a star occurred in 1999 and was confirmed visually by five observers and once photoelectrically, with the chords yielding an estimated elliptical cross-section of {{nowrap|184 × 144 km}}.[9]Photometric observations of this asteroid were made in early 2009 at the Organ Mesa Observatory in Las Cruces, New Mexico. The resulting light curve shows a synodic rotation period of 46.551 ± 0.002 hours with a brightness variation of 0.14 ± 0.02 in magnitude.[4] It has the longest rotation period of an asteroid more than 150 km in diameter.[11] As a primitive C-type asteroid[5] it is probably composed of carbonaceous material. References 1. ^1 {{cite web |title=JPL Small-Body Database Search Engine: diameter > 150 (km) and rot_per > 24 (h) |publisher=JPL Solar System Dynamics |url=https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=all;obj_kind=all;obj_numbered=all;OBJ_field=0;ORB_field=0;combine_mode=AND;c1_group=OBJ;c1_item=Ap;c1_op=%3E;c1_value=150;c2_group=OBJ;c2_item=As;c2_op=%3E;c2_value=24;table_format=HTML;max_rows=50;format_option=comp;c_fields=AcBhBgBjBiBnBsAiApAs;.cgifields=format_option;.cgifields=ast_orbit_class;.cgifields=combine_mode;.cgifields=table_format;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=com_orbit_class&query=1&c_sort=AsD |accessdate=2015-06-06}}
2. ^1 {{Citation | first1 = Lutz D. | last1 = Schmadel | title = Dictionary of Minor Planet Names | publisher = Springer | page = 26 | volume = 1 | edition = 5th | date = 2003 | isbn = 3540002383 | url = https://books.google.com/books?id=VoJ5nUyIzCsC&pg=PA26 | postscript= .}}
3. ^1 {{Citation | last1 = Dunham | first1 = D. W. | last2 = Goffin | first2 = E. | last3 = Manek | first3 = J. | last4 = Federspiel | first4 = M. | last5 = Stone | first5 = R. | last6 = Owen | first6 = W. | display-authors = 1 | title = Asteroidal occultation results multiply helped by Hipparcos | work = The Minor Planet Bulletin | volume = 73 | issue = 3 | page = 662 |date=September 2002 | bibcode = 2002MmSAI..73..662D | postscript= .}}
4. ^1 2 {{Citation | first1 = Frederick | last1 = Pilcher | title = Rotation Period Determinations for 120 Lachesis, 131 Vala 157 Dejanira, and 271 Penthesilea | work = The Minor Planet Bulletin | volume = 36 | issue = 3 | pages = 100–102 |date=July 2009 | bibcode = 2009MPBu...36..100P | postscript= .}}
5. ^1 2 {{Citation | last1 = Tedesco | first1 = E. F. | last2 = Williams | first2 = J. G. | last3 = Matson | first3 = D. L. | last4 = Weeder | first4 = G. J. | last5 = Gradie | first5 = J. C. | last6 = Lebofsky | first6 = L. A. | display-authors = 1 | title = A three-parameter asteroid taxonomy | work = Astronomical Journal | volume = 97 | pages = 580–606 |date=February 1989 | doi = 10.1086/115007 | bibcode = 1989AJ.....97..580T | postscript= .}}
}} External links - {{AstDys|120}}
- {{JPL small body}}
{{Use mdy dates|date=October 2012}}{{Minor planets navigator |119 Althaea |number=120 |121 Hermione}}{{Small Solar System bodies}}{{DEFAULTSORT:Lachesis}}{{C-beltasteroid-stub}} 7 : Background asteroids|Discoveries by Alphonse Borrelly|Minor planets named from Greek mythology|Named minor planets|C-type asteroids (Tholen)|C-type asteroids (SMASS)|Astronomical objects discovered in 1872 |