GALAXIES LIKE GRAINS OF SAND

The universe just got ten times more crowded.

Less than a century ago, astronomers believed that the Milky Way galaxy--our home galaxy--comprised the entire universe. In 1924, astronomer Edwin Hubble discovered galaxies, "island universes" far beyond the Milky Way. As telescopes got bigger and better, and eventually were sent into space, researchers estimated that the observable universe--the part of the universe from which light has had time to reach Earth--contained some 120 billion galaxies.

Hubble Ultra-deep field, 2014. Credit: NASA

Today, a team of researchers from NASA and ESA (the European Space Agency) released the results from a new and more accurate 3-D galactic census. The find that for every galaxy astronomers can see with today's telescopes, there are at least 10 that will be detected by the next generations of instruments.

"It boggles the mind that over 90% of the galaxies in the universe have yet to be studied," says the study's lead author, Christopher Conselice.

So it looks as though we live in a universe not with 120 billion other galaxies, but 1.2 trillion. With an average galaxy containing, say, 100 billion stars, that makes the star count around 10 to the 23rd power, or 10 with 23 zeroes after it.

It seems like pretty much every astronomical discovery, starting with Copernicus' shocking revelation in 1543 that Earth is not the center of the cosmos, has had the effect of pointing out that we're not quite as significant in the big scheme of things as we might like to think. 

The good news is that knowing that we're just the inhabitants of the third planet around one star out of a hundred billion in one galaxy out of a trillion does put our current worries--right down to the size of a particular presidential candidate's hands--into perspective.

(And hats off to British science fiction author, Brian Aldiss, for the evocative and prophetic title of his 1960 book, Galaxies Like Grains of Sand.)