The universe is put together like Swiss cheese – some regions are the cheese; others are the holes. The “cheese” consists of clusters and superclusters of galaxies. The “holes” are just that – cosmic voids. The largest voids span more than a billion light-years.

Cosmic voids were discovered half a century ago. Astronomers were looking deep enough into the universe to map its structure on the largest scale. They’d expected the universe to look the same in all directions – a smooth blend of galaxies. Instead, they found a web – overlapping filaments of galaxies, with big spaces between.

The voids might be there because there were tiny differences in the density of matter in the early universe – especially dark matter. The gravity in the denser regions pulled material together to make stars and galaxies. That left the less-dense regions almost empty. They contain a few galaxies, some gas and dust, and some dark matter, but not much else.

More than 6,000 voids have been cataloged. They clump together to make supervoids. One of the closest is the Boštes Void – “the Great Nothing.” It’s centered about 700 million light-years away, and it spans more than 300 million light-years – a giant “hole” in the universe.

Boštes climbs into view in early evening. Look for the bright yellow-orange star Arcturus, which is low in the east by 9 or 10 o’clock. The Great Nothing stretches to the upper left of Arcturus.

Script by Damond Benningfield