... Tonight's Sky . ... Supernova showered Earth with radioactive debris . ... Sky Guide . ... The farthest supernova yet for measuring cosmic history . Scientists used Hubble Space Telescope data to discover the most distant well-measured type Ia supernova ever found. ... Measuring the history of expansion ultimately depends on comparing distance and redshift for enough type Ia supernovae over a long expanse of time. ... Only registered members of Astronomy.com are allowed to comment on this article. ...