The sun that coughed

V838 MonocerosFollowing up on observations from Earth-based telescopes, NASA’s Hubble Space Telescope is pointed toward the star V838 Monocerotis – an object of very little previous interest – to discover why it’s suddenly the brightest thing in the entire Milky Way Galaxy. What Hubble sees surprises scientists on the ground: a “shell” of matter surrounding the star, illuminated from within and expanding outward into space (actual photo sequence seen here). What astronomers had seen previously was the illumination of the dust cloud, which is much larger than the star itself. Scientists theorize that the expanding dust cloud is not an indication of a supernova, but a sign that V838 Monocerotis is expanding, expelling gas and then shrinking again. The star is over 20,000 light years from Earth.