The Subaru Telescope discovered many Type-Ia supernova that lie at least 10 billion light-years away, including a dozen that ranked among the most distant and ancient at the time of discovery. These findings demonstrate Subaru’s ability of deep imaging. The data analysis showed that supernova were exploding about five times more frequently in the young universe, about 10 billion years ago, than they do today. This is an important discovery suggesting that heavy elements like iron were produced much faster in the early universe.