A composite image of the oldest known supernova, called RCW 86, has just been released by NASA. The photograph contains X-ray data from the NASA Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory, as well as infrared data from the NASA Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (WISE).
Together, these images combine in a unique view that highlights the remnants of a supernova that blew up more than two millennia ago. We know about the event because it was witnessed by Chinese astronomers for about 8 months.
I find it particularly interesting that, all these years later, astronomers were still able to look at the object, and establish that it was produced following the explosion of a Type Ia supernova.