Image credit: NASA/JPL/Space Science Institute

 

Members of the science team of the Saturn-bound Cassini spacecraft have observed the bright star Rigel rising through hazes over the horizon of the ringed planet.

 

Observing the change of brightness of a star when it is occulted by a planet yields interesting information about the structure and thickness of the planet's atmosphere.

 

Rigel is the seventh brightest star in the sky. It is one of the stars of the winter constellation Orion, the great mythological hunter. Its name is of Arabic origin, meaning "the leg of the great man". Rigel is a giant blue star, located about 900 light years away. It shines brightly in our skies due to its large size and high surface temperature.

 

A star's color is determined by its temperature. The blue stars are the hottest, with surface temperatures of up to 50,000° K; the red stars are coolest, at about 3,000° K. The Sun is a yellow star whose surface temperature is about 5,800° K.

 

Further reading

Cassini Mission Homepage

http://saturn.jpl.nasa.gov/home/index.cfm