A composite image of the remnant of Kepler’s SupernovaNASA/CXC/SAO/D.Patnaude One of the most famous exploding stars ever recorded by humanity may have been an invader from another galaxy, according to a new analysis of its movements. What is more, alien stars like this might be behind 1 per cent of all the supernovae we see in the galaxy. In 1604, astronomers saw a new, incredibly bright star appear in the sky, outshining any other. German astronomer Johannes Kepler, who also derived some of the first laws of planetary motion, observed the star for a year to track its…