Cepheus is a constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 in the northern sky. It is named after Cepheus, King of Aethiopia

Cepheus, King of Aethiopia

In Greek mythology, Cepheus is the name of two rulers of Ethiopia, grandfather and grandson.Cepheus son of Belus was the son of Belus and Achiroe, making him the brother of Danaus, King of Libya, and Aegyptus, King of Egypt. He had a wife named Iope and a son who he named Agenor after his paternal...

 in Greek mythology

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy

Ptolemy

Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

, and remains one of the 88 modern constellations.
γ Cephei

Gamma Cephei

Gamma Cephei , traditionally named Errai, Er Rai, and or Alrai, is a binary star system approximately 45 light-years away in the constellation of Cepheus. Gamma Cephei contains an apparent magnitude of 3.22. The visible part of the system is a stellar class K1III-IV orange subgiant star on its...

 is a binary star

Binary star

A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...

 approximately 50 light years away from Earth. The system consists of an orange subgiant and a red dwarf

Red dwarf

According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....

. Due to the precession of the equinoxes

Precession of the equinoxes

In astronomy, axial precession is a gravity-induced, slow and continuous change in the orientation of an astronomical body's rotational axis. In particular, it refers to the gradual shift in the orientation of Earth's axis of rotation, which, like a wobbling top, traces out a pair of cones joined...

, γ Cephei will be the pole star

Pole star

The term "Pole Star" usually refers to Polaris, which is the current northern pole star, also known as the North Star.In general, however, a pole star is a visible star, especially a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent...

 between AD 3000 and 5200

6th millennium

The sixth millennium is a period of time that will begin on January 1, 5001, and will end on December 31, 6000.-Astronomical events:* 5001 September 11: Mercury occults Regulus* c...

, with the closest approach to the celestial pole around AD 4000.