Hotter stars emit blue light; cooler stars emit red light.

The closest star we know of that exploded as a supernova is the one that left behind the Gum Nebula (named for Colin Gum, an Australian astronomer who discovered it in 1950). The star was only around 1,500 light-years away. At its peak, that supernova may have shone as brightly as the full moon for several weeks; however, that occurred 11,000 years ago, and the Stone Age humans of the time left no evidence of what they saw or thought about it. (source)