How do distant galaxies differ from those nearby? (Advanced)

Please tell me if I'm picturing this correctly. The further out into the universe we can see, the further in time we observe. In our own area, or neighborhood, most of the galaxies are like our own, spiral in nature, but at the very edge of the observable universe, the galaxies are eliptical? Globular? Non-spiral? Is that the basic observational model? and, if so, is this model true, no matter where in the universe we look?

Or are there, let's say, pockets of spiral galaxies even at the very edge of the observable universe?

It's not that nearby galaxies are spiral and distant ones elliptical; spirals and ellipticals are found both nearby and in the most distant regions of the universe. Ellipticals are more often found in clusters, while spirals are more often found in the field away from large clusters. There are some differences between nearby galaxies and more distant galaxies, but none of them are really morphological, meaning that as far back as we can see, galaxies have pretty much the same shapes out there as they do nearby. For instance, we expect more distant galaxies to be bluer and more metal-poor, because they are younger. This seems to be the general trend.

Now, some galaxies seen in the Hubble Deep Field, the most distant galaxies observed, do appear to be "in pieces," i.e. single spiral arms, half-galaxies, and things like that. It's unclear, though, as to whether those galaxies really represent the majority of galaxies at that distance. After all, we can only see the brightest ones, and those always tend to be the most active and most peculiar.

And finally, yes, the distribution of galaxy shapes is the same no matter which direction you look.

This page was last udated on June 27, 2015

About the Author

Dave Kornreich

Dave was the founder of Ask an Astronomer. He got his PhD from Cornell in 2001 and is now an assistant professor in the Department of Physics and Physical Science at Humboldt State University in California. There he runs his own version of Ask the Astronomer. He also helps us out with the odd cosmology question.

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