Similar in size and grand design to ou ownMilky Way, spiral galaxy NGC 3370 lies about 100 millionlight-years away toward the constellation Leo.Recorde herein exquisite detail by the Hubble Space Telescope' Advanced Camera for Surveys,the big, beautiful face-on spiral does steal the show,but the sharp image also reveals an impressive array ofbackground galaxies in the field, strewn acrossthe more distant Universe.Looking within NGC 3370 theimage data has proved sharp enoughto study individual pulsating stars known a Cepheids whichcan be used to accurately determine this galaxy's distance.NGC 3370 was chosen for this study because in 1994the spiral galaxy was also home to a well studied stellarexplosion -- a type Ia supernova.Combining the known distance to thi standard candle supernova,based on the Cepheid measurements, with observationsof supernovae at even greater distances,can reveal the size and expansion rate of th Universeitself.
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