This is a common question: what is the nearest star to the Earth that can explode as a supernova? Most people say Betelgeuse, a red supergiant in Orion, but there are several stars that are closer.
In the video below I answered this question as part of my weekly live video chat.
If you have an astronomy question you want answered, tune in to the live chat, which I usually do on Sundays at 15:00 Mountain time (21:00 UT). I might make a video of your Q&A!
Some notes: the image of Spica is used under the Creative Commons license, and is from fdecomite's Flickr set. The awesome white dwarf illustration is from my friend the artist David Hardy (and PPARC), who gave me permission to use that in my book, so hopefully he won't mind if I plug him here.