Now for something completely different: a tour of the universe!

We interrupt our usual discussion of politics for a moment.

The word "galaxy" comes from Greek for "milk."  That's because to the ancients the white band of countless stars that we call the Milky Way looked like spilled milk.

Bet you thought it was a sciency term, eh?  Yeah, well...

All the stars we can see are simply "points of light"--too far away to see a disk.  But as far back as the 1700s astronomers saw other objects in the night sky that were NOT points, but fuzzy blurs.  They were...curious about why those blurs weren't points.

Way back in 1771 an astronomer (Charles Messier) using a four-inch telescope (cutting edge tech back then!) compiled a catalog of 45 of these fuzzy objects (later expanded by others to 102 or so).  Sadly, even cutting edge technology of 1771 wasn't enough to reveal what the blurry things were.

Almost no one imagined that some of these fuzzy objects might be collections of 100 BILLION stars, like our own Milky Way.

By chance, on very clear nights another cluster of stars can be seen with the unaided eye near the Milky Way.  It's called Andromeda, first mentioned in 965 A.D.  Without a telescope it's just a faint cloudy area.  Those were called "nebula"--clouds. 

After the telescope was invented (around 1600), things took off.  Now astronomers could see that Andromeda had an elliptical shape, and in 1755 German philosopher Immanuel Kant proposed that our Milky Way actually looked like Andromeda.  If seen from "above" both would be circular, which would appear elliptical if viewed from an angle.  

But if viewed edge-on it would look like a band of stars--which is what the Milky Way looked like.  If Kant was right, it suggested that Andromeda and our Milky Way were two similar "island universes."

It was a breakthrough concept, but at the time it couldn't be proven.  (For sticklers, it still can't be *proven* but "We make a few assumptions..." and see if they can be disproven.)

In 1888 the first photos of Andromeda were taken, but the telescopes of the day weren't big enough to resolve individual stars.  So despite Kant's guess, the prevailing view of "duh experts" was that Andromeda was just a gas cloud ("nebula") in our own Milky Way," rather than a separate galaxy.

The truth--that Andromeda was indeed an "island universe" like our own--was only discovered in 1924, when astronomer Edwin Hubble (yeah, the guy NASA named the space telescope for) used a very sophisticated technique to estimate its distance from us.  

And here we need to go to math.  (Don't panic.)  The distances between stars is SO vast that astronomers don't use miles, but a distance called a "light-year," which is how far light travels in a year.  Duh.

As some of you may have heard, light travels at 186,000 miles every second.  There are 31,536,000 seconds in a year.  Multiply those two numbers and you find the number of miles in a light-year.  All you care about is it's a BDN--college shorthand for "big damn number."  (For those who do care, it's 5.87 Trillion miles.)

The diameter of "our" Milky Way galaxy is estimated to be 105,700 light-years.  Kinda challenging since we're looking at it edge-on, eh?

In 1924 Hubble found that Andromeda--the closest galaxy to us (other than ours)--was 2.54 MILLION light-years away, almost 25 times the diameter of our own galaxy.  Meaning it clearly wasn't part of our galaxy.  So "island universe" indeed.

The takeaway is that until 1924 we didn't know that other galaxies like our own existed, or that our Milky Way would turn out to be a "barred spiral" like many others.

More interesting numbers:  It's estimated that "our" galaxy contains over 100 billion stars.  

Andromeda turns out to be...bigger.  Ten times bigger, with an estimated one trillion (1,000 billion) stars.  And the largest galaxies are estimated to contain 100 trillion stars.

Estimated number of galaxies: between 200 billion and 2 trillion.  Those estimates are obviously different by a factor of ten.  That huge uncertainty is due to the fact that the best earth-bound telescopes are limited by atmospheric refraction--waviness--which limits what they can detect.  But when the raaacist, misogynist U.S. launched the Hubble space telescope, and  pointed it at what appeared to scopes on Earth as a tiny empty region of the sky, the space telescope found another thousand or so galaxies.  

The area it surveyed was so tiny that if we assumed the whole sky was like that, and integrated the thousand or so "new" galaxies over area of the whole sky you get the upper figure of 2 trillion galaxies.

Eh, all academic, right?

As you're mulling over all that, here's the rest of the story:  If you pass the light gathered by a telescope through a plain glass prism, and take a picture of the resulting rainbow spectrum, you see very narrow black lines, called "absorption lines."  These are due to specific wavelengths of light being absorbed by atoms around the star.  ("How the hell do you know that?") 

From lab experiments we know the element causing those lines is hydrogen.  (Other elements have been detected, but only traces.)  ALL stars tested in our galaxy--thousands to tens of thousands--have the same absorption lines, which suggests that all stars--if composed mainly of hydrogen--will have those same lines.

But in 1912 astronomer Vesto Slipher found that in light from Andromeda those absorption lines weren't where they should have been.  Instead they were shifted slightly--almost imperceptibly--toward a longer wavelength--a "red shift."

The equations governing that shift in wavelength (thus in apparent frequency) were developed in 1842 by Austrian physicist Christian Doppler, who had noticed--as many had--that the pitch of whistles on steam engines changed as the engine passed.  (Surely you've noticed that, right?)

Unless the stars in Andromeda somehow used a different fuel, Doppler's equations said the entire Andromeda "thing" (whatever it was) was moving away from us at 190 miles per second.  Interesting.
 
Seventeen years later (1929), using a much better telescope, Hubble found that when he took pics of the light from what were now known to be more-distant galaxies, those lines were red-shifted much more, meaning the more distant galaxies were moving away faster--in a few cases something like 50,000 miles per second.  

WTF?!! 

Now: If you were to paint dots on a balloon and inflate it, the dots on the far side would be moving away faster than nearby dots, right?

Bingo: looks like the universe is expanding.

It gets better: If you take the estimated distance to the most distant galaxies, and the speed they're moving away from us, and do a bit of math (ignoring the Left's bleat dat maff beez raaaacist)), you can get an estimate for a time when all the matter in the universe was in one big glob--thus an estimate of the age of whole the universe.

May be horseshit but frankly I think that's impressive.

If you're curious, the current estimate is 13.8 billion years.  Not that it matters, eh?

Now the caveat: every reference I've read talks about "galaxies" being known in the 1770s.  That's totally misleading: yes, the telescopes of the day could see blurry patches, but except for a couple of lucky guesses, astronomers didn't realize until 1924 that those blurs were actually "island universes" vastly farther away than stars in our own galaxy.

Now back to our regular programming about what policies will give the U.S. at least a chance to survive more or less as we knew it as teens, eh?

Democrats: "Why would anyone want dat?  Duh U.S. wuz (an' IZ) raaacis' an' misogynistic an' jus' AWFUL!  An' yew din' care nuffin' 'bout Globull Worming!"

Me: "ESAD, morons."