AMATEUR NATURALIST

Orienting yourself to the stars

Posted Feb. 12, 2012, at 4:50 p.m.
A map of North: Ursa Major, aka the Great Bear, aka the Big Dipper, aka the Plow.
Photo courtesy of Hubblesite/A. Fujii
A map of North: Ursa Major, aka the Great Bear, aka the Big Dipper, aka the Plow.

The key to stargazing is points of orientation.

In the beginning, like for all beginnings, you take the simple points first, which in the case of stargazing is simply the brightest stars. There are two ways to use the bright stars, and like practically everything else in the universe, the two ways tend to merge: orientation by individual star and orientation by constellation. I mean, some stars are very bright and easy to spot, and some constellations are very prominent to the eye.

For example, in a clear field looking north at our latitudes (44.67 degrees north here in Troy), most people can pick out the bowl and handle of the Big Dipper without much help. Once you’ve got it, you can never miss it again. And a nice advantage to it is that in our part of the world it’s always up there; it never sets, it just whirls around and around night after night, sort of comforting in a way.

But anyway, once you have the Big Dipper (or Ursa Major, the Great Bear) for a point of orientation, the geography of the whole northern sky opens up. The two outer stars of the bowl make a line pointing northward at a fairly bright star — this is Polaris, the North Star. From Polaris you can trace a somewhat fainter curve of stars around to another smaller dipper — the Little Dipper (Ursa Minor, the Little Bear). And in the Big Dipper’s handle, the two end stars point roughly toward the fourth-brightest star in the sky, reddish Arcturus.

These are all, with a little patience and focus, easy to find, and you can never get lost in the northern sky again. That feels like it could come in pretty handy at some point, though I’m not sure when, exactly.

There are clear points of orientation in other parts of the sky in different seasons, too. In summer a fairly easily spotted constellation is the Northern Cross, or Cygnus, the Swan. It’s not quite as distinct as the Big Dipper because there are more visible stars in its vicinity, but once your eye lights on it, it’s in your memory for good because its five stars are in the exact proportion of a cross, or a flying swan or goose. To the side of the swan’s head end is the fifth-brightest star we see, Vega. A couple of skips farther on the other side of the swan’s head is another bright star, Altair. On August and September nights Altair is near the southwest horizon in the constellation Aquila, the Eagle, whose four brightest stars, when your eye catches them, look like a flattened diamond.

In September and October, if you look east just after sunset you’ll see four fairly bright stars in a distinct box shape, with few other stars visible among them; this is the Square of Pegasus. If you scan to your left a little bit, your eye will enter a star field, and in it are four quite bright ones in a lopsided W — this is Cassiopeia.

In winter the most striking shape in the southern evening sky is Orion, with his three-star belt and a sword hanging vaguely off it. Two bright stars above and below are at his head, or more precisely his shoulder (reddish-colored Betelgeuse), and foot (cold, bluish Rigel). At his heel is the brightest star in the sky that’s not the sun, Sirius, the Dog Star in the shoulder of Canis Major, the Big Dog, bounding along behind the hunter.

Now these are just beginnings. These bright stars and constellations are like outposts in space from where you can navigate further out. This is not like a video game. But with patience and repetition (they’re there every clear night, year after year), you’ll see less obvious constellations start to emerge from the welter of lights, like Hercules, which is a lopsided box with four stars like appendages shooting off it, between Ursa Major and Vega. Nearby is a crownlike semicircle of stars called Corona Borealis.

Between the Square of Pegasus and Cassiopeia is Andromeda, where if you’re patient and know how to use binoculars (simple — hold them up to your eye, aim them at something and focus the image), on clear nights you can pick up a smudge of light that is actually a galaxy, M31, 2.5 million light-years away.

These stars and constellations are bright points of orientation on your maps of the stupendous elsewhere that will eventually, if you let them, burn themselves into your mind. That could come in handy sometime. I’m not exactly sure how yet.

Dana Wilde’s collection of Amateur Naturalist and other writings, “ The Other End of the Driveway,” is available electronically and in paperback from Booklocker.com.

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