Four Supernova Remnants . ... Credit Copyright: NASA , CXC , SAO Explanation: These four panels show x-ray images of expanding cosmic debris clouds, tens of light-years across, in nearby galaxy the Large Magellanic Cloud . ... Clockwise starting at the upper left are remnants aged 600 years, 1,500 years, 10,000 years and 13,000 years. ... The fourth (lower left) is a Type II explosion - triggered by the final collapse of the core of a massive star . ... NASA Official: Jay Norris. ...