This X-ray image of Tycho’s supernova, first seen as a visible-light object by Tycho Brahe in 1572, was taken in 2003 by the Chandra X-ray Observatory. Gas and dust with temperatures in the millions of kelvins (shown in red and green) are expanding outward at about 10 million km/hr (6.2 million mi/hr), following a shell of high-energy electrons (blue).