WASHINGTON (TIP): Nasa has made the most precise measurement yet of the Hubble constant, the rate at which our universe is expanding. The Hubble constant is named after the astronomer Edwin P Hubble, who astonished the world in the 1920s by confirming our universe has been expanding since it exploded into being 13.7 billion years ago. In the late 1990s, astronomers discovered the expansion is accelerating , or speeding up over time.

Determining the expansion rate is critical for understanding the age and size of the universe, Nasa said. Nasa’s Spitzer Telescope took advantage of longwavelength infrared light to make its new measurement. “Spitzer is yet again doing science beyond what it was designed to do,” said project scientist Michael Werner at Nasa’s Jet Propulsion Laboratory in Pasadena, California. Werner has worked on the mission since its early concept phase more than 30 years ago. “First, Spitzer surprised us with its pioneering ability to study exoplanet atmospheres,” said Werner, “and now, in the mission’s later years, it has become a valuable cosmology tool,” said Werner.

Dark energy is thought to be winning a battle against gravity, pulling the fabric of the universe apart, researchers said. “This is a huge puzzle,” said lead author Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena. “It’s exciting that we were able to use Spitzer to tackle fundamental problems in cosmology.”