Polaris remains still point in changing world


By Tom Burns - Stargazing



Polaris, the North Star, has been the most important star in the sky to humans since they first looked up at the nighttime sky. Yet, 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. Polaris stays put while the other stars seem to rotate around it. For many ancient cultures, the Pole Star was a starry god around which the cosmos did a stately, worshipful dance.

To understand why Polaris does not move, picture an imaginary line passing 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 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 relatively 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 precisely the same number of degrees as our latitude.

Since we live at 40 degrees north latitude, Polaris will be 40 degrees up, about halfway 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. They would spin slowly around the sky parallel to the horizon throughout the night like some cosmic merry-go-round.

Polaris is the star at the tip of Ursa Minor’s (the Smaller Bear’s) tail. Because of their locations, you can’t talk about Polaris without saying something about Ursa Minor, the Little Bear.

The first record of the constellation and Polaris comes from Babylonian star maps, which identified the stars of Ursa Minor as the “Wagon of Heaven.”

Before the Greeks settled on the “Little Bear” designation, the bear’s tail was called Kynosoura, which most scholars translate as “the dog’s tail.”

As the Greek civilization gave way to the later Romans, “Kynosoura” became the Latin “Cynosure.”

However, the Latin word has a new meaning — “a center of admiration or attention.”

By the second century CE, Polaris and the stars of Ursa Minor become the symbolic representation of the goddess Psyche, the embodiment of the human soul.

In his work “The Golden Ass,” “Roman novelist Apuleius (born around 125 CE) tells the story of Cupid and Psyche. In it, he refers to the famed Cynosure of their age.”

The story is far too complex and involved to tell here. Suffice it to say that Psyche, the Soul, falls in love with Cupid, the god of erotic love. He spurns her, however.

Her quest to reunite with Cupid is physically, emotionally, and spiritually taxing. She even chooses to descend into the dark Underworld. But despite all of her travails, she remains steadfast in her love.

In the end, her steadfastness is triumphant. Cupid and Psyche are married. The goddess Soul achieves perfect harmony as spirit and body are united.

Polaris and its steadfast location in the sky had an important practical application. 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. It was the only reliable way of judging a ship’s motion at sea.

The Greek astronomer and mathematician Thales of Miletus (circa 600 BCE) picked up both the Babylonian Wagon and the maritime associations. None of his writing survives, but a third-hand account states that the Greeks “measured the stars of the Wagon by which the Phoenicians sail.”

The passage from Thales hints that ancient Phoenicians were perhaps the first seafarers to use Ursa Minor and Polaris as a guide.

According to the Greek poet Aratus (circa 270 BCE), “The Phoenicians put their trust in [Kynosoura] when they cross the sea.” “By her guidance then,” he continued, “the men of Sidon [Phoenicians] steer the straightest course.”

Later, 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 William Cullen Bryant, a 19th century American poet, 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. Some Arab cultures called it 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. Polaris isn’t a single star.

A small telescope will reveal its fainter companion star, Polaris B, which orbits Polaris once every 30 years or so. In fact, Polaris has at least one other companion, making it not a star but a star system.

Sadly, modern astronomy has dented the North Star’s halo. It isn’t precisely north.

Point a telescope at it and observe it throughout the night. It will change position, slowly describing a small circle in the telescope’s eyepiece field.

More significantly, the Earth wobbles slowly on its axis like a top. Thus, the stars slowly change their orientation to the poles.

The imaginary line that points north has not always pointed at Polaris. Five thousand years ago, the star Thuban in the constellation Draco marked the pole.

Thirty-five thousand years hence, the nearest star to the northern pole will be Vega in the constellation Lyra.

Sometimes steadfastness is an illusion, a creature of the brief time we inhabit the planet.

There is much to learn from the old constellation myths, and Psyche’s story is no exception. We must reach deep into our souls for steadfastness against the constant winds of change.

Five morning planets

Starting on June 20 and extending through the rest of the month, June mornings allow us to see all five naked-eye planets.

You’ll need an unobstructed eastern horizon (free of trees and buildings) to see all five. Observing under a dark, rural sky wouldn’t hurt either.

Go out about 4 a.m. Start by looking in the southeast for Saturn as a bright, pale-yellow point of light.

You’ll find it about 35 degrees above the horizon. (Zenith, the point straight overhead, is 90 degrees.)

Jupiter is to the left and slightly down from Saturn. It will be much brighter and whiter than Saturn.

To the left and down from Jupiter is ruddy Mars. Next comes brilliant Venus, low on the ESE horizon.

The most challenging planet is Mercury, which gets a scant three or four degrees above the horizon before morning twilight ruins the view. Scan down and to the left of Venus with binoculars.

Notice how the planets appear along a shallow arc across the sky. You have discovered the ecliptic, the path along which the sun, moon, and planets appear to move.

If you have a telescope and a star map on your phone, you can also see Uranus (between Venus and Mars) and Neptune (between Jupiter and Saturn) along the ecliptic.

As morning twilight illuminates the world around you, look down at your feet. You have now observed all the planets in our solar system.

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By Tom Burns

Stargazing

Tom Burns is the former director of the Perkins Observatory in Delaware.

Tom Burns is the former director of the Perkins Observatory in Delaware.