On October 13, 1773, French astronomer Carles Messier discovered the first spiral galaxy, the Whirlpool Galaxy, or better known as M51a (the “M” is for Messier).  Messier (pronounced:  mess-see-ay), however, didn’t have a clue what he was looking at.  He thought it was a nebula. 

 

A nebula (or nebulae if plural) is a cloud of dust, often the remains of a star or the birthplace of a new one.  Relatively speaking, they’re small, anywhere from one to 500 lightyears across.  OK, 500 lightyears is not that small.  But we’re talking about space where everything is relative.  A galaxy can be anywhere from 100 lightyears across to one million.  Take the Milky Way, where we call home, living far out in the unchartered backwaters of the unfashionable end of the western spiral arm.  It’s 100,000 lightyears across, give or take. 

 

But, you see, Messier really had no idea what he was looking at because his optics simply were not that good.  On a dark night in the fall, away from city lights, if you look to the northeast you can see the Andromeda Galaxy with the naked eye.  Of course, it’s only going to look like a blurry smudge up there in the sky, which is exactly what a nebula looks like.  You need scale for the stars, and really anything, to make sense.

 

So Messier’s discovery was just another blurry something until William Parsons, who you probably know better as the Third Earl of Rosse, or just Lord Rosse for short, trained his overly large telescope, which he just had lying around his castle in Ireland, on Messier’s blur.  And for the first time, on an evening in 1845, a spiral pattern of stars was identified.

 

It wouldn’t be until the 1920s, though, that really smart guy Edwin Hubble was able to determine it was a galaxy separate from ours.  This, then, was the first time humans finally figured out that other galaxies existed.  A lot of them.  The further we look, the more that we can see.  Using the James Webb Space Telescope it is now estimated that there are at least two trillion galaxies that we can see.  Each galaxy can contain hundreds of millions of stars.  So the total number of stars... is a really big number.

 

By recognizing these other galaxies we not only know that the Milky Way isn’t the only galaxy... not even close, we now have a more accurate scale of just how big everything is... or might be.  Instead of thinking of distances in terms of thousands of lightyears, we are now thinking in terms of billions of lightyears.  That ought to humble you.

 

Perhaps the biggest discovery by Hubble was that all of those galaxies were moving.  Everything was moving, and all of it away from everything else.  The Universe was expanding... but from where?  If they’re all moving away, then they all had to have a common starting point.  The Big Bang.  All of that from some French guy who looked up at the sky and said, “Hmmmmm....”

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