This image shows a composite view of the Crab Nebula, an iconic supernova remnant in our Milky Way galaxy, as viewed by the Herschel Space Observatory and the Hubble Space Telescope. A wispy and filamentary cloud of gas and dust, the Crab Nebula is the remnant of a supernova explosion that was observed by Chinese astronomers in the year 1054. The image combines Hubble's view of the nebula at visible wavelengths, obtained using three different filters sensitive to the emission from oxygen and sulphur ions and is shown here in blue. Herschel's far-infrared image reveals the emission from dust in the nebula and is shown here in red. While studying the dust content of the Crab nebula with Herschel, a team of astronomers have detected emission lines from argon hydride, a molecular ion containing the noble gas argon. This is the first detection of a noble-gas based compound in space.