April 19 – Up, Up, And A Milky Way!

Today’s factismal: There are about 5,000 galaxies (including the Milky Way) in the Virgo Supercluster, and over 100,000,000,000 galaxies in the Universe!

There is a poem by Jonathan Swift that goes like this:

The vermin only teaze and pinch
Their foes superior by an inch.
So, naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite ’em,
And so proceed ad infinitum.

What Swift’s poem leaves out is that the same is true in the other direction. Consider the Sun; to we terrestrials, it seems huge, but it is only one medium-sized star out of hundreds of billions in the Milky Way galaxy that we call home. And just as the local stars are grouped into the Milky Way, the Milky Way is one of about 54 galaxies grouped into what the astronomers forthrightly call the Local Group. (Or maybe 55 galaxies, if you’ve seen the news about the “hidden” galaxy!) And the Local Group is just part of the Virgo Supercluster which includes at least a hundred groups of galaxies which means at least five thousand galaxies which means at least five hundred thousand, thousand, thousand stars just in our neighborhood.

The Milky Way galaxy (My camera)

The Milky Way galaxy
(My camera)

But wait! it gets bigger! The Virgo Supercluster is just part of the Laniakea Supercluster (aka the Local Supercluster) which has 100,000 galaxies. And that is just a small part of the Universe as a whole. All told, there are about 100 billion galaxies in the Universe, divided into about 100 million superclusters and holding around 300 sextillion stars. Put another way, if we were to give away all of the stars in the Universe, every person on Earth would get fourteen galaxies with about 42 trillion stars total to play with.

Just a few of the galaxies in the Virgo Supercluster (Image courtesy NASA/ESA/ESO/NAOJ/G. Paglioli;)

Just a few of the galaxies in the Virgo Supercluster
(Image courtesy NASA/ESA/ESO/NAOJ/G. Paglioli)

Of course, if you want to play with your toys, you need to know how they are made. And that’s where the citizen science comes in. (You knew I’d get there eventually.) Over at Galaxy Zoo, they are trying to decipher how galaxies change over time. Do they have growth spurts? Do they change shape? Do they suddenly start dating? In order to answer these questions and many more, they need citizen scientists to look at pictures of galaxies and tell the scientists things like the number of arms and the relative brightness of the stars in the galaxy. To take part (and see some pretty cool images), send your browser to:
http://www.galaxyzoo.org/

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