Excuse me, there’s a galaxy in my coffee

I’m a teacher by trade, and Decem­ber can be a try­ing time for ped­a­gog­ics. What with recal­ci­trant stu­dents, big stacks of papers to mark, sleep­less nights — most of them cloudy and star­less — and cold, snowy dri­ves to work, Decem­ber is not the most enliven­ing of months.

How­ever, the occa­sional clear night pro­vides a bit of long-distance inspiration.

If one comes your way, check out the Androm­eda Galaxy (M31, for short), which rises high in the east by the end of evening twi­light right now. From even mod­estly dark skies, the galaxy is vis­i­ble to the unaided eye, mak­ing it the far­thest object that most folks can see with­out opti­cal aid.

Sadly, a whirlpool-shaped col­lec­tion of 300 bil­lion stars is reduced to an elon­gated fuzzy patch when it’s 2.5 mil­lion light years away. (One light year is six tril­lion miles.) We don’t see it from the top, which means we can’t observe its round, spi­rally splen­dor. The galaxy is tilted at about a 45-degree angle, mak­ing it look vaguely cigar-shaped.

Despite its mind-melting dis­tance, the Androm­eda Galaxy stretches all the way across most binoc­u­lar fields. It looks big because it IS big — 150,000 light years wide.

Its size and tilt cre­ate a mind-melting pecu­liar­ity. The front edge of the galaxy is con­sid­er­ably closer to us than the back end. You see the light from the back of the galaxy 100,000 or so years after you see the front end. In effect, M31 is so big that you don’t see it all at the same time.

The Androm­eda Galaxy gets its spi­ral shape because of its spin. The cen­tral por­tion of the galaxy travel around the galac­tic core quite rapidly. Stars at the periph­ery take hun­dreds of mil­lions of years to make one rev­o­lu­tion. The outer stars lag behind the inner ones, a process that stretches the outer stars into a pinwheel.

That the galax­ies have such a rev­o­lu­tion­ary tem­pera­ment should not sur­prise us. Our own planet revolves around the sun, and it wouldn’t be here at all if it didn’t. The plan­ets of our solar sys­tem move in a per­fect bal­ance between their veloc­ity, which makes them want to fly away from the sun, and the sun’s enor­mous grav­ity, which holds them in. Stop Earth’s rev­o­lu­tion, and our planet would sim­ply fall into the sun.

The same is true of the Androm­eda Galaxy and, come to think of it, our own Milky Way. Stop the rev­o­lu­tion of any galaxy, and the whole she­bang would col­lapse by its own grav­ity to a very dense and com­pact lump. So thank good­ness for the swirl, which is, in fact, one of those fun­da­men­tal engines that keeps the uni­verse in balance.

These things became very clear to me at 5 a.m. one morn­ing as I sat in front of a cup of cof­fee at an all-night diner after a night of observ­ing galax­ies far from home. My 8 a.m. class was on my exhaustion-encrusted mind as I per­formed a sim­ple experiment.

You can per­form it, as well, if you’re will­ing to engage in an early morn­ing astro­nom­i­cal endeavor. Give your cup o’ Joe a quick, vig­or­ous stir, and then pour in the cream.

That morn­ing, dis­cour­aged, tired, and despon­dent, as I poured the cream into the cup, a per­fect spi­ral galaxy formed in the swirling black brew. The same force that stirs our morn­ing cof­fee rules the universe.

I was ready to teach. Astro­nom­i­cally speak­ing, inspi­ra­tion some­times comes from very far away, but some­times we can find it in our third cup of morn­ing coffee.

Please come to a Perkins pub­lic pro­gram! Call 740– 363‑1257 for more information.

Plan­ets

Venus is low in the south­west dur­ing evening twi­light. You’ll need a hori­zon rel­a­tively free of trees and build­ings to see it as a bril­liant point of light.

Bright Jupiter is high in the south­east just after dark.

Mars is high in the ESE by 4 a.m. as an orange point of light. Tele­scop­i­cally, it’s a tiny orange dot and hardly worth a look.

Sat­urn is always worth a look. To the unaided eye, it looks like a pale yel­low star low in the ESE at about 5 a.m.

Tom Burns is direc­tor of Ohio Wes­leyan University’s Perkins Obser­va­tory in Delaware. He can be reached at tlburns@owu.edu.

Posted by Tom Burns on Dec 12 2011. You can follow any responses to this entry through the RSS Feed. Comments can be made below.