The Crab Nebula never fails to disappoint—and that's particularly true in this image, a view by the Herschel Space Observatory and the Hubble Space Telescope of the swirling cloud of dust and gas.

The image is a composite from the two satellites, combing Hubble's view of the nebula at visible wavelengths and Herschel's far-infrared data. The result reveals the electromagnetic emissions from the dust in the nebula. The images have revealed the presence of argon hydride—a molecular ion containing the noble gas argon—ion the crab nebula for the first time. In fact, that's the first ever detection of a noble-gas based compound in space. Clever and pretty. [NASA]

Image by ESA and NASA