The constellation Cepheus


Nome latino
Emisfero settentrionale
All year round
588 deg²
Stella più luminosa
Alderamin (HIP number 105199)
Open star clusters, galaxies
The constellation Cepheus

Cepheus, a symbol of King Cepheus, is a prominent constellation near the North Star and the celestial North Pole. In its area are a couple of interesting deep-sky objects. Its mythological origin lies in Greece and reflects an interesting story.

Hemisphere, visibility, and area

The constellation Cepheus is located in the northern hemisphere near the celestial pole. Therefore, it can be seen from anywhere in the northern half of the globe. South of the equator, however, it is almost invisible.

In latitudes like Central Europe or Canada, Cepheus is circumpolar. This means that it is visible all year round. In more southern regions, the months from June to February offer a good view of the constellation.

It has an area of approximately 588 square degrees, making it a medium-sized constellation. Compared to the other 88 constellations, it ranks 27th.

Cepheus is very distinctive with its striking shape. In most visualizations, five stars form a kind of house. Four of them are connected to form a square, and two lines run to the fifth star, representing the roof of the house.

The brightest star is the star that forms a corner of the house to the southeast. Its name is Alderamin (Latin: α Cephei, Alpha Cephei). It is a star that has 18 times the luminosity of our sun. Its apparent brightness is approximately 2.4, and its distance from earth is around 49 light-years.

To find Cepheus in the night sky, it is helpful to look for the well-known star Polaris, as Cepheus is located close to it and orbits it. In addition, the adjacent constellations provide a good orientation aid. Cepheus is nestled between six other constellations in the sky. Its neighbors include the well-known Ursa Minor (often called Little Dipper), the Draco, and the Cygnus. But also, the Lacerta, Cassiopeia, and the Camelopardalis are among the neighboring constellations.

Specialties in the constellation

In the region of Cepheus, there are several exciting deep-sky objects. There are a number of open star clusters as well as a galaxy.

One of the open star clusters is NGC 188. With its age of around 6.3 billion light-years, it is one of the oldest star clusters in the Milky Way. The cluster consists of approximately 5,000 stars. It was discovered by the German-British astronomer William Herschel in November 1831.

The galaxy with the catalog number NGC 6946 is a barred spiral galaxy. It bears the nickname Fireworks Galaxy and is located on the border with the neighboring constellation of Cygnus. It was also discovered by William Herschel, but already in 1798.

Observing the galaxy is made difficult by the dust and gas of our galaxy. NGC 6946 is very close to our galactic plane, which darkens it significantly.

Barred spiral galaxy NGC 6946
Barred spiral galaxy NGC 6946


According to Greek mythology, the constellation represents King Cepheus. With his wife Cassiopeia, he fathered his beautiful daughter Andromeda.

The proud mother claimed that she and her daughter were more beautiful than the Nereids, the daughters of the titan Neureus. At that time, the Nereids were considered the embodiment of beauty. After Cassiopeia's statement, the Nereids became angry and wanted revenge. So, Amphitrite, the wife of the sea god Poseidon and a daughter of Nereus asked her husband for help.

Poseidon was willing to help and sent the sea monster Cetus to the kingdom of Cepheus. There, it was supposed to destroy the coasts. It flooded fields near the beach with salty seawater and mercilessly sank merchant ships and fishing boats until a famine finally broke out.

Desperate, Cepheus visited the oracle of Siwa and begged for advice. It determined that Cepheus had to sacrifice his daughter Andromeda to appease the water god. Eventually, he chained Andromeda to a rock and left her to her fate.

But before anything happened, Perseus, a mythical heroic figure and son of Zeus, appeared. He saved the beautiful maiden from the sea monster Cetus and killed it. Later, he married her and founded a large family.

To commemorate this story, all those involved were set as a constellation in the sky.

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