Explanation: The large stellar association cataloged as NGC 206 is nestled within the dusty arms of neighboring spiral galaxy Andromeda (M31), 2.5 million light-years distant. Seen near the center of this gorgeous close-up of the southwestern extent of Andromeda's disk, the bright, blue stars of NGC 206 indicate its youth. Its youngest massive stars are less than 10 million years old. Much larger than the clusters of young stars in the disk of our Milky Way galaxy known as open or galactic clusters, NGC 206 spans about 4,000 light-years. That's comparable in size to the giant stellar nurseries NGC 604...