New Galaxy

If you look at images of galaxies captured by the Hubble Space Telescope, they look like they’ve been around forever, and will last forever. But the structure of the Universe has been changing over the 13.7 billion years since the Big Bang. New galaxies have formed, and older galaxies have merged together.

Scientists think that grand spiral galaxies like our own Milky Way probably started out as a collection of new dwarf galaxies; the first to form after the Big Bang. Over time, these new galaxies merged together into larger and larger groups. Because of conservation of momentum from all the individual stars, these large galaxies started to spin, flattening out into a disk with grand spiral arms.

But this is just a single stage in the ongoing evolution of galaxies. When we look out into the Universe, we can see the older, redder irregular galaxies. These are made up of so many stars and merged galaxies that they just look like giant blobs. But they can have hundreds of times the mass of our own Milky Way galaxy and be 10 times as luminous.

The further we look, we keep discovering new galaxies. The deepest look that astronomers have ever seen is with the Hubble Deep Field Survey. In this image, Hubble stared at a single spot in the sky that was thought to be empty for hundreds of hours. The images contained thousands of galaxies, many were billions of light-years away.

New galaxies are forming all the time as smaller galaxies merge together. In fact, in about 10 billion years, our own Milky Way will merge with Andromeda, creating an even bigger new galaxy: milkomedia.

We have written many articles about the galaxies for Universe Today. Here’s an article about the upcoming merger between the Milky Way and Andromeda, and here’s another article about the collision.

If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.

We have also recorded an episode of Astronomy Cast about galaxies – Episode 97: Galaxies.