Has a supernova ever been seen?

The supernova SN 1006 appeared in the southern constellation of Lupus during the year 1006 CE. This was the brightest recorded star ever to appear in the night sky, and its presence was noted in China, Egypt, Iraq, Italy, Japan and Switzerland. It may also have been noted in France, Syria, and North America. read more

Yes. Less than thirty years ago we saw Supernova SN 1987A explode in the Large Magellanic Cloud (one of our neighbouring dwarf galaxies) less than 200,000 light-years away. Reaching magnitude 3, it was clearly visible to the naked eye, and we have been keeping a close telescopic eye on it ever since. read more

Yes, many of them have been seen. In the Milky Way, the latest (Kepler's Supernova) was seen by Johannes Kepler in Northern Italy on October 9, 1604. It could be seen by the naked eye for 18 months. The earliest recorded observation was of SN185 by the chinese astronomers on 185 AD. read more