NASA Cassini spacecraft imaged the surface of Saturn moon Helene as the it flew by the moon on Jan. 31, 2011. Helene is a Trojan moon of Dione, named for the Trojan asteroids that orbit 60 degrees ahead of and behind Jupiter as it circles the Sun.
NASA Cassini spacecraft imaged the surface of Saturn moon Helene as the it flew by the moon on Jan. 31, 2011. Helene is a Trojan moon of Dione, named for the Trojan asteroids that orbit 60 degrees ahead of and behind Jupiter as it circles the Sun.