Q&A OF THE YEAR
WHAT IS THE BOÖTES VOID?
SPACE IS FULLL OF HOLES
BY DR ELIZABETH PEARSON
In 1981, Robert Kirshner was working with other astronomers at the University of Michigan to calculate the redshifts –a measure of how fast something is moving away from Earth – of a great number of galaxies. Due to the way our Universe is expanding, the farther away a galaxy is the faster it moves, meaning redshift can be used to measure distance. Kirshner and his team were taking advantage of this to create a 3D map of the Universe. As the map became fleshed out, something strange appeared. At 700 million light-years from Earth was a blank void. In a roughly spherical region around 330 million light-years wide –a region the Milky Way could fit into billions of times over – there were barely any galaxies.