Light Echoes from V838 Mon . ... Credit Copyright: NASA , ESA, H. E. Bond ( STScI ) Explanation: What caused this outburst of V838 Mon? ... A stellar flash like this had never been seen before -- supernovas and novas expel matter out into space. Although the V838 Mon flash appears to expel material into space, what is seen in the above image from the Hubble Space Telescope is actually an outwardly moving light echo of the bright flash. ... NASA Web Site Statements, Warnings, and Disclaimers . ...