There are at least seven artists/band that go by the name Astro. The first is a 'space-noise' project by Hiroshi Hasegawa (C.C.C.C., Astromero, Astral Travelling Unity, Senssurround Orchestra, YBO²). Hiroshi's myspace page for Astro can be found here, and his official site containing info on his many different projects here.
The second is a new Korean R&B group formed in early August, 2009, consisting of 1 male vocal, 1 female vocal, and 2 rappers.