118 Peitho

{{Short description|Main-belt asteroid}}

{{Use dmy dates|date=October 2019}}

{{Infobox planet

| minorplanet=yes

| background=#D6D6D6

| name=118 Peitho

| discoverer=Karl Theodor Robert Luther

| discovered=15 March 1872

| mpc_name=(118) Peitho

| image=000118-asteroid shape model (118) Peitho.png

| caption=3D convex shape model of 118 Peitho

| alt_names=A872 EA

| pronounced={{IPAc-en|'|p|aɪ|θ|oʊ}}'Pitho' in Noah Webster (1884) A Practical Dictionary of the English Language

| adjective=Peithoian {{IPAc-en|p|aɪ|'|θ|oʊ|.|i|ə|n}}

| named_after=Πειθώ Peithō

| mp_category=Main belt

| epoch=31 July 2016 (JD 2457600.5)

| orbit_ref=

| semimajor={{Convert|2.43757|AU|Gm|abbr=on}}

| perihelion={{Convert|2.03988|AU|Gm|abbr=on}}

| aphelion={{Convert|2.8353|AU|Gm|abbr=on|lk=on}}

| eccentricity=0.16315

| period=3.81 yr (1390.1 d)

| inclination=7.7427°

| asc_node=47.701°

| arg_peri=33.403°

| mean_anomaly=51.1620°

| avg_speed=18.95 km/s

| dimensions={{val|41.73|1.5|ul=km}}

| mass=7.6{{E|16}} kg

| density=

| surface_grav=0.0117 m/s²

| escape_velocity=0.0220 km/s

| rotation={{Convert|7.8055|h|d|abbr=on|lk=on}}
7.823 h

| spectral_type=S

| abs_magnitude=9.14

| albedo={{val|0.2240|0.017}}

| single_temperature=~178 K

| mean_motion={{Deg2DMS|0.25898|sup=ms}} / day

| observation_arc=144.05 yr (52615 d)

| uncertainty=0

| moid={{Convert|1.05849|AU|Gm|abbr=on}}

| jupiter_moid={{Convert|2.4367|AU|Gm|abbr=on}}

| tisserand=3.473

}}

118 Peitho is a main-belt asteroid. It is probably an S-type asteroid, suggesting a siliceous mineralogy. It was discovered by R. Luther on March 15, 1872, and named after one of the two Peithos in Greek mythology. There have been two observed Peithoan occultations of a dim star: one was in 2000 and the other in 2003.{{cite journal |title=Planet (118) Peitho |author= von Boinik, I. F. B. |journal=Astronomische Nachrichten |volume= 145 |pages=31 |url=http://articles.adsabs.harvard.edu/full/seri/AN.../0145//0000021.000.html| bibcode=1897AN....145...31V|doi=10.1002/asna.18981450107}}{{Cite web |url=http://pdsproto.jpl.nasa.gov/catalog/target/Results.CFM?resultsselbox=118%20PEITHO |title=NASA Planetary Data System |access-date=2009-12-21 |archive-url=https://web.archive.org/web/20090801122528/http://pdsproto.jpl.nasa.gov/catalog/target/Results.CFM?resultsselbox=118%20PEITHO |archive-date=2009-08-01 |url-status=dead }}

This body is orbiting the Sun with a period of 3.81 years and an eccentricity (ovalness) of 0.16. The orbital plane is inclined by 7.7° to the plane of the ecliptic. The cross-section diameter is ~42 km. In 2009, Photometric observations of this asteroid were made at the Palmer Divide Observatory in Colorado Springs, Colorado. The resulting asymmetrical light curve shows a synodic rotation period of 7.823 ± 0.002 hours with a brightness variation of 0.15 ± 0.02 in magnitude. This was reasonably consistent with independent studies performed in 1980 (7.78 hours) and 2009 (7.8033 hours). The lightcurve inversion process has been used to construct a model of this object, suggesting a blocky shape with flattened poles.