The Universe is built in layers. The fundamental units, you could argue, are
stars. Some are solitary (like the Sun), some orbit each other as binary stars.
By the hundreds or thousands they comprise clusters, and if you have a few
billion to a few hundred billion, you get a galaxy.
Our Milky Way is part of a small group of about 50 other galaxies, most of
which are smallish dwarfs. The next step up from a group is a galaxy cluster,
which can contain hundreds to thousands of galaxies.
One of the nearest galaxy clusters is Abell 1367, more commonly called the
Leo Cluster. A search of the astronomical literature shows it’s unclear how many
galaxies can be considered Leo citizens; there are at least 70 major galaxies
and perhaps many more. It’s 300 million light-years away in the constellation of
Leo (of course).
And it’s gorgeous. Astronomer Adam Block took
an amazing image of the central region of the cluster using the 0.81 meter
Schulman telescope on Mt. Lemmon in Arizona:
A city of galaxies: the Leo Cluster.
All photos by Adam Block/Mount Lemmon SkyCenter/University of Arizona
And it goes up from there. The Coma Supercluster, along with many others,
forms a structure called the
Great Wall, a vast complex hundreds of millions light-years long.
It’s one of the largest structures in the entire Universe, but there are many
like it.
It’s incredible, mind-numbing. The scale of the Universe crushes our sense of
size, fills our capacity of awe to overflowing. I know some people despair when
they think about this, but it has the opposite effect on me: I am uplifted. Not
only is it wonderful enough that such things exist at all, but how astonishing
is it that we can see them, study them, understand them? Perhaps not completely,
of course, not yet and perhaps never in their entirety.
But we can try. And that makes us important, even at the tiny, tiny scale of
this vast, vast Universe we inhabit.
