What's the VAR! plate, you ask? (I mean, I assume a few of you followed me because I'm an astronomer, right?)
So, did you ever see the #FatherTed clip about cows -- these ones are small, those are far away? Space is pretty much like that. In this case, though, the cow was the Andromeda Nebula. Was it small, but close to us? Or huge and really far away? If the Universe was just the Milky Way, it had to be the former. If the latter? Then the Universe is a whole lot bigger!
Astronomers will tell you that, at this time, there was a great debate -- no, a The Great Debate -- between two leading scholars at the Smithsonian Natural History Museum. This debate ignited public interest and set the stage for what was to come.
(These astronomers are probably *vastly* overselling how important this debate was. People with niche hobbies tend to do that with minor events.)
There's this relation -- now called the Leavitt Law -- that for stars that have periodic variations (bright, faint, bright, faint), you can connect how long it takes to complete a cycle with how *intrinsically* luminous it is.
If you know the period, you know how bright it is. Compare that to how bright it appears, and you know a star's distance. So, by finding a variable star in Andromeda, Hubble had found a way to directly measure its distance -- and to solve the Great Debate!
I'd like to think that Hubble realized this was a variable, did the math in his head, and could barely write "VAR!" with how excited he was, before running out into the Pasadena afternoon crying "EUREKA!"
This photo is the moment the scale of the Universe changed, from thousands of light years to a bare minimum of millions.
100 years ago we went from a small house among many in a vast country to a tiny pebble of sand in an incomprehensible ocean.
Also, if you're thinking "Hey, I followed you because you're an astronomer, why don't you post more astronomy things!"
--> @ThomasConnor
It's only 100 yrs since that discovery. 100 yrs. (~3 generations), since we know, that we are living in an island galaxy - surrounded by billions of such galaxies.
The human race exists for at least 300.000 yrs. (~100.000 generations).
Not the only hint showing us, that we live in a very special time period...
Another hint in the grafic below!
@hendric It's "V1" -- and we've gone back to look at it, since. Hubble used the 100 inch Hooker telescope, albeit with a photographic plate instead of modern CCDs. My wholly off-the-cuff guess would be you'd need something a little bigger than that, all the same.
But there have been follow on projects: https://hubblesite.org/contents/news-releases/2011/news-2011-15.html
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