This space wallpaper is an artist’s impression showing the exotic double object that consists of a tiny, but very heavy neutron star that spins 25 times each second, orbited every two and a half hours by a white dwarf star. The neutron star is a pulsar named PSR J0348+0432 that is giving off radio waves that can be picked up on Earth by radio telescopes. Although this unusual pair is very interesting in its own right, it is also a unique laboratory for testing Einstein’s theory of gravity — general relativity — in ways that were not possible up to now. So far the new observations exactly agree with the predictions from general relativity and are inconsistent with some alternative theories. This image was released April 25, 2013.