Reverse of medal commemorating the bright comet of 1577. Known as Brahe's comet, this is the comet which convinced the Danish astronomer Tycho or Tyge Brahe (1546-1601) that there is change beyond the sphere of the Moon. It is shown in his system of the universe published in his Mundi aetherei recentioribus Phaenomensis, (1588). The reverse shows Phaeton driving his father Phoebus's (the Sun) chariot.