Mar. 31st, 2014


Mar. 31st, 2014 10:22 pm
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Some years back I visited my mother when she lived in a house in Green Valley, Arizona.  From the back yard you could see the MMT Telescope up on the top of Mount Hopkins.  The MMT was originally the Multiple Mirror Telescope, with six mirrors that, uh, happened to be available, combined into one telescope.  Since then the art of making Really Big Mirrors advanced and the six 1.8 meter mirrors have been replaced by a single 6.5 meter mirror, but they were unable to replace the name with a new one, so it's still the MMT.  (I understand that they tried, but astronomers aren't very good at naming telescopes, as evidenced by names like "very large array" or "overwhelmingly large telescope.") It's DARK there.  Even down in the town.  Really, really, dark.  I grew up in Cook County, Illinois.  Chicago, famously, is in Cook County.  I thought Milwaukee was dark.  Cook County is like standing on the daytime side of Mercury compared to Green Valley.

Anyway, I saw the very obvious Milky Way, the bazillion stars in the plain of our own galaxy.  Back when I was younger, I thought of the Milky Way as something you could detect using binoculars, a region of many faint stars.  I didn't realize until later how obvious it is in the dark.  More interesting than that, I found and pointed out to Mom something just a bit harder to see, M31, the great galaxy in Andromeda.  From 2.5 million light years away, you'd think it would be very faint, but the combined light of a trillion stars adds up to a lot of light.  From such a distance, you'd think anything would look like a point, but galaxies are very, very big, and it appears even to the naked eye as an extended smear of light even though you can only see the brightest part.  There weren't even really humans as we know ourselves when light from those trillion stars left there.  And, of course, it's headed right at us.  In three or four billion years the galaxies will pass through each other and stars will be thrown out in vast bands and eventually the two supermassive black holes will merge, an event that I assume would be best observed from a Safe Distance.  I'm pretty sure in the case of supermassive black holes a safe distance is a very long distance indeed.

And, you know, Andromeda is part of the Local Group.  You can see it just by looking (if you get the hell away from Chicago).  It's not like it's far away or anything, as these things go.

(That photo of me with a Nikon film camera reflected in the 10 meter array of mirrors was taken up at the Whipple observatory.)


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