Keppler's Star

On this day in 1604 something strange was spotted in the night sky. Supernova 1604 was, by all accounts, a very bright event. For three weeks in October and November of the year 1604 it outshone all other stars and planets, with the exception of Venus. It's main claim to fame though was it was the last supernova to be observed in our own galaxy, lighting up the constellation of Ophiuchus on the celestial equator for about three weeks, before slowly fading into obscurity until it's remains were rediscovered in the modern era. The above image show's how the remnants appear today.

The other interesting thing about SN1604 is that it was observed by Johannes Kepler from Northern Italy. Kepler, a German who is most famous for his laws of planetary motion, was already making a name for himself as a mathematician, astronomer and astrologer and was a key figure in the 17th century scientific revolution. Kepler had heard the news of a 'new star' but did not believe the rumours until he saw it for himself. He then began systematically observing the star over the next fe weeks. He studied the star's astronomical properties while taking a sceptical approach himself to the many astrological interpretations then circulating. He noted its fading luminosity, speculated on its origin, and used the lack of observed parallax to argue that it was in the sphere of fixed stars. The birth of this new star implied a variability in the heavens that would not go unnoticed.

Interestingly this was the second supernova to be observed in a generation. SN 1572 was seen by Tycho Brahe in the constellation of Cassiopeia. Since then no other supernovae have since been observed with any certainty in the Milky Way, though many others outside our galaxy have of course been seen. For many modern astronomers, two supernovae occurring within 32 years of each other would be a gift from the heavens.