The Moon backlights the IceCube neutrino observatory at the south pole. The observatory uses special detectors buried deep in the ice to catch the ghostly particles known as neutrinos, which are produced in the hearts of stars, in stellar explosions, around black holes, and in other energetic locations. The Antarctic ice filters out other particles, ensuring that scientists are detecting only the neutrinos. IceCube is being upgraded to make it more sensitive to the particles. [Raffaela Busse/IceCube/NSF]