Tycho supernova remnant (SN 1572), combined X-ray and infrared image. This expanding cloud of hot gas and dust (green and yellow) formed following a type Ia supernova of a white dwarf star in 1572. The outer shock wave (circular blue line) is radiating X-rays. Heated dust (red) is also seen. SN 1572 is located in the constellation of Cassiopeia and is around 7500 light years from Earth. It has a diameter of around 16 light years and is expanding at about 9000 kilometres per second. The X-ray portion of this image was obtained in 2003 with the ACIS instrument on the Chandra X-ray Observatory. Infrared data is from the Spitzer Space Telescope (SST). Ground-based optical data is from the Calar Alto observatory, Spain.