BEAUTY: 
BRAGGING RIGHTS: You saw the North Star
HOW EASY IS IT TO SEE? Just look up
BEST TIME TO SEE IT: Year-round
TYPE: Star
DISCOVERED: Known since antiquity
If ever you need a reminder that life is short, just stare up at Stella Polaris: the Pole Star. Astronomy is filled with cycles: the daily rotation of the world, the monthly cycle of the moon, and our annual journey around the sun. Those cycles are all human-scaled, but there are many other cycles that transcend a single human lifespan. And just as fruit flies (average lifespan, 30 days) have no concept of the seasons, we humans (average lifespan, 75 years) are blissfully unaware of the changing of the Pole Star.
Once a day, our world spins on its axis, and that axis happens to point in the direction of Polaris. When you take a long-exposure picture of Polaris, you can see star trails rotating around it. This is an illusion, of course, as it is we on Earth who are rotating.
But the axis also moves! Just as a spinning top sometimes wobbles, the Earth’s axis traces a lazy circle around the sky. Polaris wasn’t always the Pole Star, and some day in the future, it won’t be anymore. The axis makes one complete circle every 26,000 years: about 350 human lifespans. That’s the equivalent of a fruit fly contemplating a 30-year mortgage.
About 26,000 years ago humans were bravely enduring the worst of the most recent ice age. I don’t know what the world will be like 26,000 years from now, but I’m pretty sure I won’t be around to see it. Life is short.
Face north. The easiest way to find Polaris is to use the Big Dipper. The two stars at the edge of the Dipper’s “bowl” always point to the North Star. The North Star will be your latitude above the horizon, facing north. For example, if you live in Boston (42 degrees latitude) you’ll see Polaris due north, 42 degrees above the horizon. At the North Pole (90 degrees latitude) you’ll see Polaris straight overhead. At the equator (0 degrees latitude) it will be right at the horizon, and south of that, you’ll never see it.
Star trails. With some practice and the right equipment you can point your camera at Polaris and get a beautiful shot of stars revolving around the pole. You’ll need a steady tripod, a digital camera, and some software to combine multiple exposures. There are several tutorials on the web that explain how.
NORTH STAR REGION IN WINTER; 30-DEGREE FIELD OF VIEW
