GK Persei, a nova that erupted in 1901, continues to surprise astronomers more than a century later. Using data from the SPHEREx space telescope, researchers discovered a large, bipolar shell of molecular hydrogen surrounding the nova. This shell, measuring 18 by 10 arcminutes, matches the shape and location of the known H-alpha nebulosity around GK Persei, which was previously thought to be an ancient planetary nebula. The hydrogen shell is most strongly detected in a specific infrared emiss...