5 Astraea

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Template:Minor Planet 5 Astraea (as-tree'-a; written Astræa in the early scientific literature) is a large main belt asteroid. Its surface is highly reflective (bright) and its composition is probably a mixture of nickel-iron with magnesium- and iron-silicates.

Image:Moon and Asteroids 1 to 10 at 10 km per px.png Astraea was the fifth asteroid discovered, on December 8, 1845 by K. L. Hencke. It was his first of two asteroid discoveries. The second was 6 Hebe. An amateur astronomer and post office employee, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him with an annual pension of 300 US$ (1968 dollars) for the discovery.

Photometry indicates prograde rotation, that the north pole points in the direction of right ascension 9h52m, declination 73° with a 5° uncertainty, ^[3]. This gives an axial tilt of about 33°.

Astrea is physically unremarkable but notable mainly because for 38 years (since the discovery of Vesta in 1807) it had been thought that there were only four asteroids. After the discovery of Astraea, thousands of other asteroids would follow.

There has been only one observed stellar occultation by Astraea (February 2, 1991).

Aspects

Stationary, retrograde	Opposition	Distance to Earth (AU)	Maximum brightness (mag)	Stationary, prograde	Conjunction to Sun
June 8, 2005	August 2, 2005	2.04497	10.9	September 24, 2005	March 6, 2006
September 8, 2006	October 24, 2006	1.64421	10.3	December 14, 2006	July 2, 2007
February 26, 2008	April 5, 2008	1.24209	9.4	May 19, 2008	December 11, 2008
May 29, 2009	July 23, 2009	2.01466	10.9	September 14, 2009	February 25, 2010
August 24, 2010	October 11, 2010	1.75512	10.5	December 2, 2010	June 9, 2011
February 5, 2012	March 13, 2012	1.14353	9.1	April 23, 2012	November 28, 2012
May 19, 2013	July 13, 2013	1.96537	10.9	September 4, 2013	February 16, 2014
August 11, 2014	September 29, 2014	1.85053	10.7	November 21, 2014	May 20, 2015
January 11, 2016	February 17, 2016	1.09393	8.7	March 26, 2016	November 13, 2016
May 9, 2017	July 2, 2017	1.89739	10.8	August 23, 2017	February 6, 2018
July 30, 2018	September 18, 2018	1.92870	10.8	November 11, 2018	May 3, 2019
December 15, 2019	January 22, 2020	1.10914	8.9	March 1, 2020	October 28, 2020

External links

• AN 23 (1846) 393 (in German)
• MNRAS 7 (1846) 27

References

1. Supplemental IRAS Minor Planet Survey
2. G. A. Krasinsky et al Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).
3. M. J. López-Gonzáles & E. Rodríguez Lightcurves and poles of seven asteroids, Planetary and Space Science, Vol. 53, p. 1147 (2005).

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ca:(5) Astrea

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