Supernova SN 2004dj resides in the outskirts of NGC 2403, a galaxy located 11 million light-years from Earth. The arrow at top right points to the stellar blast, called a supernova, which is so bright in this NASA Hubble Space Telescope image that it easily could be mistaken for a foreground star in our Milky Way Galaxy. It is the closest stellar explosion discovered in more than a decade. The star that became SN 2004dj may have been about 15 times as massive as the Sun, and only about 14 million years old. The supernova is part of a compact cluster of stars known as Sandage 96; many such clusters (blue regions) as well as looser associations of massive stars can be seen in this image. The heart of NGC 2403 is the glowing region at lower left. Sprinkled across the region are pink areas of star birth. This image was taken on August 17, two weeks after Japanese amateur astronomer Koichi Itagaki discovered the supernova on July 31, 2004, with a small telescope.