SN 1006: Supernova Remnant in X Rays . ... CXC , NASA Explanation: This huge puff ball was once a star. One thousand years ago, in the year 1006 , a new star was recorded in the sky that today we know was really an existing star exploding. The resulting expanding gas from the supernova is still visible with telescopes today, continues to expand, and now spans over 70 light years . ... Foreground stars are visible that have nothing to do with the supernova. ... NASA Official: Jay Norris. ...