SN 1572 was seen by Tycho Brahe. This supernova helped astronomers learn that things in space could change. SN 1604 was seen by Johannes Kepler. It was the last supernova close enough to be seen from Earth's northern hemisphere without a telescope. SN 1987A is the only supernova so close that scientists could find neutrinos from it. SN 1987A was also bright enough to see without a telescope. People in the southern hemisphere saw it.