By Tom Burns
April 7, 2014
Polaris, the North Star, has been the most important star in the sky to humans since they first looked up at the heavens. Contrary to popular belief, it is not the brightest in the heavens. (It’s 49th on the list.)
We prize it above all others because of its steadfastness. In a world of constant change, we seek an anchor to secure us against the ever-shifting seas of life. Polaris is a starry lodestone that always keeps its northerly position in the sky.
Other stars shift their positions moment by moment while Polaris stays put. The other stars seem to rotate around it, as if the Pole Star were some starry god around which the cosmos must do a stately dance of worship.
To understand why Polaris does not move, picture an imaginary line that passes through the North and South poles. The Earth spins around that line. Extend the line above the North Pole, and it points almost directly at the Pole Star.
The stars don’t actually rise and set. The Earth’s turning makes them appear to do so. The North Pole doesn’t move from its position, and hence its star does not move.
To find the North Star, look toward the Big Dipper. Find the two stars that form the front of the Dipper and use them as pointers. Look for a star in a rather empty part of the sky. Polaris is a star apart.
Alternatively, you can simply look north. Since we live in the northern hemisphere, Polaris will sit above the horizon by exactly the same number of degrees of our latitude. Since we live at 40 degrees north latitude, Polaris will be 40 degrees up, about half way between the horizon and the zenith, i.e., straight overhead. Just above Earth’s equator, the pole star will barely make it above the horizon.
At the North Pole, Polaris will be straight overhead. I’ve always wanted to go there and do some stargazing. The stars would not rise and set. Over the course of a night, they would spin slowly around the sky parallel to the horizon like some cosmic merry-go-round.
Because its location in the sky indicates the observer’s northerly location, humans have looked to the Pole Star for guidance for a long time.
Sailors called it Stellar Maris, the Star of the Sea, and Navigatoria, the Steering Star. Many a storm-tossed seaman prayed for its return on gray and dangerous nights. As poet W.C. Bryant wrote in “Hymn to the North Star:”
On thy unfaltering blaze
The half-wrecked mariner, his compass lost,
Fixes his steady gaze,
And steers undoubting, to the friendly coast.
But most of all, it was the central pivot upon which all stars turned. To some American Indian tribes, it was the nail that held up the bowl of night. To Hindus, it was Grahadhara, the Pivot of the Planets.
Arab cultures referred to it as Al Kaukab al Shamaliyy, the Star of the North. Muslims used it to orient themselves toward Mecca for their prayers. In ancient India, newlyweds looked to the Pole Star as a symbol of their fidelity, promising under its unchanging light to remain faithful for a hundred autumns.
Polaris is interesting in another regard: The Pole Star isn’t a single star. Even a small telescope will reveal its fainter companion star, Polaris B, which orbits Polaris once every 100,000 years or so. In fact, Polaris has at least three other companions, which makes it not a star but a star system.
Sadly, modern astronomy has put a dent in the North Star’s halo. It isn’t exactly north. Point a telescope at it and observe it over the course of a night. It will change position, slowly describing a small circle in the field of the eyepiece.
Secondly, the Earth wobbles slowly on its axis like a top. Thus, the stars slowly change their orientation with respect to the poles. The imaginary line that points north has not always pointed at Polaris. Five thousand years ago, the pole was marked by the star Thuban in the constellation Draco. Thirty-five thousand years hence, the nearest star to the pole will be Vega in the constellation Lyra.
Sometimes steadfastness is an illusion, a creature of the brief time we inhabit the planet. Reach into your own heart for steadfastness. The only constant in the universe around you is constant change.
Tom Burns is the director of Perkins Observatory. He can be reached at email@example.com.