Skymania writes Bright supernova explodes in nearby galaxy M82. "One of the closest stellar explosions for years has been spotted in a relatively nearby galaxy that is a favourite target for amateur astronomers. The supernova appeared in the galaxy Messier 82, or M82 for short, which lies about 11.4 million light-years away, right on our doorstep in cosmic terms."
It's right near the Big Dipper. Right now it's 12th magnitude in brightness so you need a telescope to see it, but it's expected to get brighter over the next couple of weeks, maybe to the point that you can see it in binoculars (magnitude 8 or so).
The other interesting thing (aside from the fact that's it an exploding star) is the kind of explosion it is. By looking at the frequencies of light coming from it (the spectrum) astronomers can determine the kinds of elements in the explosion. This is a Type 1a supernova, a white dwarf in orbit with another star pulls in enough matter that it explodes. The neat thing about these is they always explode with the same brightness. If you know a light bulb is 100W, and you can measure how bright you see it and you can figure out its distance. If you don't know how bright the bulb actually is, you can't figure out if it's a bright bulb very far away or a dim bulb closeup. Type 1a supernovae are one of the important ways we measure the distance of galaxies.
There's some more info about the M82 supernova at CosmoQuest Blog. "It’s… odd. M82 is the nearest starburst galaxy to us. That means it is producing new stars at a prodigious rate. When you have lots of new star formation, you get massive stars going BOOM as core-collapse supernovae, whereas the white-dwarf supernovae can happen just about anywhere there are old stars (which happens to be just about anywhere there are any stars.) So although it is intuitively weird that this exciting nearby, visible supernova in a starburst galaxy is a white-dwarf type and NOT core-collapse, who are we to question nature if it wants to give us such a gift."