Scientists have given the most accurate estimate yet of how fast the universe is expanding. A team of astronomers used Nasa’s Spitzer Space Telescope to clock the expansion of the cosmos at a phenomenal 46 miles per second per megaparsec. American astronomer Edwin Hubble was in the Twenties first to discover that space is constantly expanding and has been growing continuously since its inception.
Astronomers now believe that the universe exploded into being about about 13.7billion years ago, so determining the rate of the continuing expansion, known as Hubble’s constant, is critical for gauging its age and size.
Spitzer’s new measurement, which took advantage of long-wavelength infrared instead of visible light, improves upon a similar, seminal study from NASA’s Hubble Space Telescope by a factor of three, bringing the uncertainty down to only 3 percent, a giant leap in accuracy for a cosmological measurement.
The newly refined value, in astronomer-speak, is: 74.3 ± 2.1 kilometres per second per megaparsec (a megaparsec is roughly 3million light-years). ‘Just over a decade ago, using the words “precision” and “cosmology” in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two,’ Ms Freedman said. ‘Now we are talking about accuracies of a few percent. It is quite extraordinary.’