If you look high in the northwestern sky toward the end of evening twilight you'll easily find the familiar stars of the Big Dipper. Shoot an imaginary arrow through the two stars in the bottom of the bowl to the right, and you'll arrive at Polaris, the North Star. Several faint stars arc upwards from Polaris to form the handle of the Little Dipper. These connect to a small, rectangular "bowl" that completes the outline of Ursa Minor the Little Bear.
If you can see the Little Dipper, however dimly, you're ready to meet the dragon. While not especially bright, Draco's shape is so distinctive, it's easier to find that one might expect. It also helps that he's tucked between the two Dippers, which nicely frame the constellation. To locate the dragon, use the Pointers again, but this time stop at the very first star they point to — that's the tip of the Draco's tail.
Once you find it, wend your way up the tail between the two Dipper bowls, then over the top and down the side of the Little Dipper. From there, shoot straight up to a small diamond-shaped group of stars that outline the dragon's head called the Lozenge. The Lozenge — a narrow rhombus — is the brightest and easiest part of the constellation to see. Easy to recognize star patterns within a constellation or shared by two or more constellations are called asterisms. The topmost stars of this asterism, named Rastaban and Eltanin, form the dragon's eyes.
Once you find Draco's sinuous outline I think you'll agree that with just a little imagination it really does resemble a real dragon. How that beast came to inhabit the sky makes for an interesting tale. . . or tales, actually.
In Greek mythology there's often more than one story behind a constellation's origin. As one of his twelve labors, Hercules the Strongman had to gather golden apples from a special tree given to Zeus's wife Hera as a present. Ladon the dragon guarded the tree. While Hercules distracted and then killed the dragon with an arrow, his fellow conspirator, Atlas, snatched the apples.
When Hera learned of Ladon's death she placed him in the sky between the Dippers as a tribute. In another story, the Roman goddess Minerva slew the dragon in a great battle and threw him up into the sky where he froze into place, still writhing, at the north celestial pole. Take your pick.
The only writhing Draco does now comes from the slow turning of the sky as the Earth spins on its axis. There are lots of double stars and galaxies in the dragon, but we'll focus on two stars of special interest, Thuban (THOO-ban) and Kuma. The first is an inconspicuous 4th magnitude star located directly across from the Little Dipper bowl.
Five thousand years ago, when the Egyptian pyramids and Stonehenge were built, Thuban was the polestar. When your ancestors looked up at the sky back then, it was their Polaris. And just like our North Star, Thuban remained in one spot in the sky as the northern constellations circled around it during the night.
We're very fortunate to have a bright, easy-to-spot polestar. But it wasn't always that way, nor will it necessarily be in the future thanks to something called precession. We're all familiar with Earth's rotation and revolution around the Sun. Less well know is that the planet wobbles like a toy top. The wobble causes the planet's axis to trace a circle in the sky over a period of 26,000 years. Our planet is slightly wider around the equator than around the poles The combined gravitational pulls of the sun and moon on that equatorial bulge are responsible for its cyclic see-saw.
You can think of the axis as a finger pointing to the North Star. The wobble makes the finger point in different directions around a circle. Right now, it points to Polaris, but from about 3900 B.C. to 1900 B.C. it pointed at Thuban. Circa 500 B.C. it had shifted closer to Kochab, the bright star in the Little Dipper's bucket, and has been ambling toward Polaris ever since.
Currently, the North Star is less than one degree from the north celestial pole, the direction in the sky the Earth's axis points. The star will pass closest to that point in 2102 — just 1/2° from true north. Then the finger will drift away from Polaris and towards the star Errai in Cepheus the King. Hang in there. The axis will circle back to Thuban again in 20,350 A.D.
After musing on Thuban, grab your binoculars and focus them on Kuma, also called Nu Draconis, the faintest star in the Lozenge at magnitude 4.9. If you can't see it because of light pollution or moonlight, just point the binoculars at the Lozenge, and it'll be the star on the lower left side.
Kuma looks like a single star with the naked-eye but neatly divides into two identical white suns separated by 62 arc seconds (1/30th the diameter of the full moon) in binoculars. The distance between them is 1,900 times Earth's distance from the sun, and they take about 44,000 years to orbit about their center of gravity. That means that for every orbit, Earth completes (very) roughly two precession cycles.
So many things spin and cycle in this universe. Rather than turtles it's more like wheels all the way down.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.