Template: Infobox Asteroid / Maintenance / Error 1
( 5) Astraea (originally ( 5) Astraea ) is an asteroid of the main asteroid belt, which was discovered on December 8, 1845 by Karl Ludwig Hencke.
It was named after celestial bodies Astraea, daughter of Zeus and goddess of justice.
Having been discovered in the years 1801-1807, the first four asteroids ( 1) Ceres, (2) Pallas, (3) Juno and (4) Vesta, it took less than 38 years until the discovery of the fifth asteroid. It was also the latest discovery of the asteroid, which took place before the discovery of the planet Neptune. Since then, the asteroids were still counted as full-fledged planet, was the following year discovered Neptune than three tenth planet counted.
With the discovery of ( 6) lifting in 1847 but began a flood of new discoveries of asteroids. Therefore, the number of ( major ) planet was on the recommendation of Alexander von Humboldt in 1851, limited to eight and the new concept of asteroid (also: planetoids or minor planets ) were introduced.
Astraea moves in 4.1 years and at a distance of 2.1 ( perihelion ) to 3.1 ( aphelion ) astronomical units around the sun. The orbit is inclined 5.4 ° to the ecliptic, the orbital eccentricity is 0.19.
Astraea has a diameter of 117 km. The asteroid has a relatively bright silicate- rich surface with an albedo of 0.23. While the opposition Astraea reached a brightness of 11.9 mag. In 16.8 hours to rotate about its own axis.