This NASA image combines data from four space telescopes to create a multi-wavelength view of all that remains of RCW 86, the oldest documented example of a supernova. Chinese astronomers witnessed the event in 185 AD, documenting a mysterious "guest star" that remained in the sky for eight months. X-ray images from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory were combined to form the blue and green colours in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova. Infrared data from NASA's Spitzer Space Telescope and WISE, Wide-Field Infrared Survey Explorer, shown in yellow and red, reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy. This is the first time that this type of cavity has been seen around a white dwarf system prior to explosion.

Credit : NASA/AFP