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.
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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 email@example.com.