Image Credit: NASA , ESA , Hubble Heritage  (STScI /AURA ); Acknowledgement: A. Reiss  et al.  (JHU )
Explanation: Is this what our own Milky Way Galaxy looks like from far away? Similar in size and grand design to our home Galaxy  (although without the central bar), spiral galaxy NGC 3370  lies about 100 million light-years  away toward the constellation of the Lion (Leo ). Recorded above  in exquisite detail by the Hubble Space Telescope ‘s Advanced Camera for Surveys , the big, beautiful face-on spiral is not only photogenic, but has proven sharp  enough to study individual stars known as Cepheids . These pulsating stars  have been used to accurately determine NGC 3370’s distance.NGC 3370  was chosen for this study because in 1994 the spiral galaxy  was also home to a well studied stellar explosion — a Type Ia supernova . Combining the known distance to this standard candle supernova, based on the Cepheid measurements, with observations of supernovas  at even greater distances, has helped to reveal the size and expansion rate  of the entire Universe itself.