The Expansion of the Universe Detected by Supernovae
The universe has been expanding since the Big Bang occurred about 14 billion years ago. The speed of the expansion is determined by the amount of matter and energy that the universe contains. By measuring the distance to a faraway object and the speed at which that object is receding from us, we can calculate the expansion rate of the universe. A Type Ia supernova is a good "beacon" for this type of measurement because its maximum luminosity can be accurately determined. In 2013, the Subaru Telescope discovered more than 40 such supernovae that lie at least 7 billion light-years away. Such observational data has helped astronomers verify with greater accuracy the acceleration of the expanding universe.