Astronomers have discovered a two-faced white dwarf star with one side made up primarily of helium and the other composed of hydrogen. "The surface of the white dwarf completely changes from one side to the other," said Caltech postdoctoral scholar Ilaria Caiazzo. "When I show the observations to people, they are blown away." Named Janus after the Roman god of transition, the white dwarf is located more than 1,300 light years away from Earth in the constellation Cygnus. Janus was found by the Zwicky Transient Facility (ZTF) in California, and researchers think its dual nature could be caused by magnetic fields which may have prevented the mixing of the two gases.