24 Themis

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For the spurious tenth satellite of Staurn, see Themis (satellite).

24 Themis

Discovery A
Discoverer	Annibale de Gasparis
Discovery date	April 5, 1853
Alternate designations B	1947 BA; 1955 OH
Category	Main belt (Themis)
Orbital elements C
Epoch August 18, 2005 (JD 2453600.5)
Eccentricity (e)	0.132
Semi-major axis (a)	468.226 Gm (3.130 AU)
Perihelion (q)	406.202 Gm (2.715 AU)
Aphelion (Q)	530.250 Gm (3.545 AU)
Orbital period (P)	2022.524 d (5.54 a)
Mean orbital speed	16.76 km/s
Inclination (i)	0.760°
Longitude of the ascending node (Ω)	35.992°
Argument of perihelion (ω)	107.989°
Mean anomaly (M)	185.968°
Physical characteristics D
Dimensions	198 km [1]
Mass	5.75±2.51×1019 kg [1]
Density	14±6 g/cm³ doubtful
Surface gravity	0.39±0.27 m/s²
Escape velocity	0.88±0.22 km/s
Rotation period	0.34892 d (8 h 23 min) [2] [3]
Spectral class	C [4] (B-V=0.68)
Absolute magnitude	7.08
Albedo (geometric)	0.067 [5]
Mean surface temperature	~159 K
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24 Themis (thee'-məs, them'-əs (key)) is one of the largest Main belt asteroids. It is also the largest member of Themistian asteroid family.

It was discovered by Annibale de Gasparis on April 5, 1853. The mass and diameter appearing in the table are from separate sources, and combining them gives an unusually large density, which is most probably wrong. The mass has very likely been overestimated by a factor of at least five times.

It is named after Themis, the personification of divine order, law and custom in Greek mythology.

[edit] Aspects

Stationary, retrograde	Opposition	Distance to Earth (AU)	Maximum brightness (mag)	Stationary, prograde	Conjunction to Sun
20 January 2005	27 June 2005	2.53419	11.9	22 August 2005	17 October 2005
19 March 2006	3 September 2006	2.23744	11.4	26 October 2006	18 December 2006
3 June 2007	9 December 2007	1.74455	10.6	24 January 2008	11 March 2008
23 September 2008	18 March 2009	2.00796	11.0	8 May 2009	27 June 2009
18 December 2009	26 May 2010	2.47353	11.8	21 July 2010	14 September 2010
16 February 2011	27 July 2011	2.45694	11.8	21 September 2011	15 November 2011
19 April 2012	14 October 2012	1.97552	11.0	2 December 2012	20 January 2013
23 July 2013	29 January 2014	1.75906	10.6	16 March 2014	3 May 2014
8 November 2014	22 April 2015	2.26743	11.5	15 June 2015	8 August 2015
17 January 2016	23 June 2016	2.53523	11.9	18 August 2016	13 October 2016
15 March 2017	29 August 2017	2.26878	11.5	22 October 2017	13 December 2017
28 May 2018	2 December 2018	1.76077	10.6	17 January 2019	5 March 2019
17 September 2019	13 March 2020	1.97299	11.0	2 May 2020	21 June 2020
13 December 2020	22 May 2021	2.45648	11.8	17 July 2021	10 September 2021

Minor planets
Previous minor planet	24 Themis	Next minor planet

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For other objects and regions, see: asteroid groups and families, binary asteroids, asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.