Draco is a constellation known as the Dragon. Draco sits close enough to the North Star to be seen in the northern sky most of the year. Draco was among the 48 constellations defined by the ancient Greek mathematician Ptolemy. Today, it is one of the 88 constellations recognized by the International Astronomical Union, the leading authority in the naming of heavenly objects.
As commonly drawn, Draco includes 16 or 17 main stars. Four stars form the head of the dragon, between the constellations Hercules and Cygnus. The body of Draco is a trail of stars that winds among the constellations Cepheus, Ursa Minor, Boötes, and Ursa Major.
Thuban, a star in the body of Draco, was once Earth’s northern polestar, about 5,000 years ago. A polestar is a prominent star closely aligned with one of Earth’s poles (see North Star ).
