Draco: The Dragon

Draco winds a long, faint loop clear around the north celestial pole, close enough to the top of the sky that it never sets from most northern latitudes. Buried in its tail is a star that used to matter enormously and now doesn't: Thuban, once the pole star, now just another faint point most people never bother to find.

The hundred-headed guardian Heracles had to kill

Draco is usually identified as Ladon, the hundred-headed serpent that guarded the golden apples of the Hesperides — a job it held until Heracles killed it during his labors. Hera, who had set the serpent to its post in the first place, placed it in the sky afterward, coiled around the north pole, permanently on watch over nothing in particular now that its job was done.

The pole star that pointed at a pyramid

Thuban, Alpha Draconis, sits at magnitude 3.65 — genuinely faint compared to the other three named stars in this pattern, and easy to miss. But around 3000 BC it was the Earth's pole star, sitting near the ecliptic pole in a way our current pole star, Polaris, does now. That alignment mattered enough to Egyptian builders that the descending passage of the Great Pyramid of Giza was oriented so that it pointed directly toward Thuban. A star doesn't move; Earth's axis slowly wobbles over thousands of years, and the point in the sky the axis happens to aim at changes with it. Thuban's moment as the axis marker has long since passed, and it will not come back around again for tens of thousands of years.

The eyes of the dragon

Eltanin, Gamma Draconis, marks the dragon's eye and is the constellation's brightest star at magnitude 2.36, an orange giant. Athebyne, Eta Draconis, sits in the dragon's head as a yellow giant at magnitude 2.73. Rastaban, Beta Draconis, marks the dragon's other eye at magnitude 2.79, also a yellow giant — so the two "eyes," Eltanin and Rastaban, are close in both brightness and color, which is a nice bit of internal consistency for a beast whose parts were mapped out star by star.

None of Draco's four named stars are dazzling on their own. What makes the constellation findable isn't any single bright point, it's the length of the winding shape itself: once you have picked out the head with its two eyes, you can trace the body's loops for a genuinely long stretch of sky, further than most constellations ask you to follow.

Two things worth a telescope

The Cat's Eye Nebula, NGC 6543, is an intricate, many-shelled planetary nebula — genuinely one of the more visually complex objects of its type, formed as a dying star sheds its outer layers in overlapping waves. The Tadpole Galaxy, Arp 188, is a disrupted spiral trailing a long tidal tail of stars, evidence of a close encounter with another galaxy that dragged material out behind it. Both are faint, telescope-and-photography targets rather than naked-eye or binocular objects.

Finding Draco in your own sky

Draco is a northern-hemisphere constellation with a best month of July, and because it winds so close to the pole, it is technically up in the sky all year for most northern observers — it just isn't always well placed or high enough to trace easily.

What this means for you tonight

Because Draco coils right around the pole, it's one of the few constellations you can try to find in almost any season from the northern hemisphere — July just puts it in the most convenient position for a comfortable look. Start at Ursa Minor: The Little Bear and Polaris, then trace outward into the loop of Draco's body curling around it; Thuban sits down in the tail, faint enough that you'll want a genuinely dark sky and a star chart to be sure you've got it rather than a random background star. If precession is a new idea to you, precession of the equinoxes walks through exactly the slow wobble that cost Thuban its job and handed the title to Polaris.

Read what a constellation really is for how a winding shape like this gets an official boundary, and how star brightness works for what a modest magnitude like Thuban's 3.65 actually looks like next to the eyes of its own dragon.