These three images taken by NASA's Hubble Space Telescope reveal the emergence of an exploding star, called a supernova. Nicknamed SN Primo, the exploding star belongs to a special class called type Ia supernovae, which are distance markers used for studying dark energy and the expansion rate of the universe. The top image shows part of the Hubble Ultra Deep Field, the region where astronomers were looking for a supernova blast. The white box shows where the supernova is later seen. The bottom left image is a close-up of the field without the supernova. A new bright object, identified as the supernova, appears in the image at bottom right. Credit: NASA/ESA/A. Riess (Space Telescope Science Institute and the Johns Hopkins Univ.)/S. Rodney (the Johns Hopkins Univ.)