Draco is a large and winding constellation located in the northern celestial hemisphere. It is one of the 88 modern constellations and has been recognized since ancient times. Draco, meaning "Dragon" in Latin, is a circumpolar constellation for many northern observers, which means it never fully sets and can be seen throughout the year. The constellation stretches over a considerable area of the sky, forming a long, winding shape that resembles a serpent or dragon.
Key Features
Draco is the eighth largest constellation in the sky, covering an area of 1,083 square degrees. It is notable for its distinctive shape, which snakes around the Little Dipper (Ursa Minor) and between the Big Dipper (Ursa Major) and Hercules. The constellation contains several deep-sky objects, including the Cat's Eye Nebula, a well-known planetary nebula, and the Draco Dwarf Galaxy, a satellite galaxy of the Milky Way.
Mythology
In Greek mythology, Draco is associated with the dragon Ladon, who was tasked with guarding the golden apples in the Garden of the Hesperides. Ladon was a fierce serpent-like dragon with one hundred heads, and he was ultimately slain by Hercules as part of his twelve labors. The dragon's body was then placed in the sky by the goddess Hera, where it became the constellation Draco.
Another mythological association is with the dragon that fought Minerva during the war between the Titans and the Olympian gods. After the dragon was defeated, Minerva flung it into the sky, where it froze around the North Pole, forming the constellation Draco.
Notable Stars
- Thuban (Alpha Draconis): Thuban is the most famous star in Draco, even though it is not the brightest. It was the North Star around 4,000 years ago, due to the precession of the Earth's axis. Thuban is a white giant star located about 303 light-years away.
- Eltanin (Gamma Draconis): Eltanin is the brightest star in Draco, with an apparent magnitude of 2.23. It is an orange giant star located about 154 light-years from Earth.
- Rastaban (Beta Draconis): Rastaban is a yellow giant star with an apparent magnitude of 2.79. It is often considered one of the "eyes of the dragon," paired with Eltanin.
Visibility
Draco is visible throughout the year in the northern hemisphere, especially during the summer months when it is higher in the sky. Its circumpolar nature makes it visible all night long for observers in latitudes above 10°N. The constellation is less visible from the southern hemisphere, where it appears lower in the sky or may not be visible at all in extreme southern latitudes.
Tips for Observing
- Identify the Big and Little Dippers: Use these well-known constellations as a starting point, as Draco wraps around the Little Dipper and lies between it and the Big Dipper.
- Look for Eltanin: Begin your search by locating Eltanin, the brightest star in Draco, which is easy to spot near the head of the dragon.
- Observe in Dark Skies: While Draco is visible even in moderately light-polluted areas, the best views of its fainter stars and deep-sky objects come under dark, clear skies away from city lights.
- Explore Deep-Sky Objects: If you have access to a telescope, try observing the Cat's Eye Nebula (NGC 6543), a bright planetary nebula, or the Draco Dwarf Galaxy (UGC 10822), a challenging but rewarding target for more advanced observers.