We know the universe is expanding, but how fast is it expanding? This question has been on the minds of astronomers since the 1930s. That’s when the observations of Edwin Hubble – for whom the Hubble Space Telescope is named – and others convincingly proved the expansion of the universe. Hubble’s Constant, or H0 (pronounced “H-nought”), is the name given by astronomers to the rate of the expansion of the universe. They’ve argued about the numerical value of Hubble’s Constant for decades, although – in the past 15 or so years – there’s been general agreement that two different observations (of Type 1a supernovae and of the cosmic microwave background) could be used to define it.
But no more.
This new ScienceCast video from NASA explains more about Hubble’s Constant, and about why astronomers now disagree. It explains why defining a numerical value for H0 is the key to comprehending the age of our universe, and its relative amounts of matter, dark matter and dark energy. It also speculates on where astronomers likely to go from here.
It’s a good one!
Bottom line: New ScienceCast from NASA about the controversial Hubble’s Constant.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.