We live in a universe of galaxies
The objects in this photo may look like stars, but they are actually galaxies in the Coma Berenices cluster of galaxies. This one cluster contains more than 1,000 galaxies. Each galaxy is a collection of billions of stars. (NASA image)
If you started from scratch – and made your own universe – would you evenly distribute the stars? Astronomer Ricardo Flores spoke to Earth & Sky about the fact that our actual universe is a universe of galaxies.
Ricardo Flores of the University of Missouri spoke about the fact that the universe isn’t uniformly filled with stars.
Ricardo Flores: You might think that things are made out of stars, the universe is filled with stars. And that’s not quite right, in the same sense that if you were flying across the country, what you would notice is that the surface of the United States is not covered with bricks. Rather, the basic unit is essentially a house.
If you could fly across the universe, you’d see that the stars don’t fill space uniformly. Instead, stars reside in galaxies. Stars are to galaxies as bricks are to a house. But as cities are collections of houses, so galaxies clump together to form galaxy clusters. Within each cluster, the galaxies are constantly on the move.
Ricardo Flores: They’re moving very fast, they’re going in and out of this structure, just like bees that are flying around. But they make a swarm that is fixed in place.
Hot gas permeates galaxy clusters – and Flores said that what keeps a galaxy cluster from flying apart is something called dark matter – undetectable but for its gravity. Flores is working to understand the shape of these invisible blobs of dark matter in galaxy clusters.
Thanks to Research Corporation, a foundation for the advancement of science.
