<P> Four Chinese constellations are contained in the area of the sky identified with Perseus in the West . Tiānchuán (天 船), the Celestial Boat, was the third paranatellon (A star or constellation which rises at the same time as another star or object .) of the third house of the White Tiger of the West, representing the boats that Chinese people were reminded to build in case of a catastrophic flood season . Incorporating stars from the northern part of the constellation, it contained Mu, Delta, Psi, Alpha, Gamma and Eta Persei . Jīshuǐ (積水), the Swollen Waters, was the fourth paranatellon of the aforementioned house, representing the potential of unusually high floods during the end of August and beginning of September at the beginning of the flood season . Lambda and possibly Mu Persei lay within it . Dàlíng (大 陵), the Great Trench, was the fifth paranatellon of that house, representing the trenches where criminals executed en masse in August were interred . It was formed by Kappa, Omega, Rho, 24, 17 and 15 Persei . The pile of corpses prior to their interment was represented by Jīshī (積 屍, Algol), the sixth paranatellon of the house . The Double Cluster, h and Chi Persei, had special significance in Chinese astronomy . Known as Hsi and Ho, the two clusters represented two astronomers who failed to predict a total solar eclipse and were subsequently beheaded . </P> <P> In Polynesia, Perseus was not commonly recognized as a separate constellation; the only people that named it were those of the Society Islands, who called it Faa - iti, meaning "Little Valley". Algol may have been named Matohi by the Māori people, but the evidence for this identification is disputed . Matohi ("Split") occasionally came into conflict with Tangaroa - whakapau over which of them should appear in the sky, the outcome affecting the tides . It matches the Maori description of a blue - white star near Aldebaran but does not disappear as the myth would indicate . </P> <P> Perseus is bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis and Cassiopeia to the north, and Andromeda and Triangulum to the west . Covering 615 square degrees, it ranks twenty - fourth of the 88 constellations in size . It appears prominently in the northern sky during the Northern Hemisphere's spring . Its main asterism consists of 19 stars . The constellation's boundaries, as set by Eugène Delporte in 1930, are defined by a 26 - sided polygon . In the equatorial coordinate system, the right ascension coordinates of these borders lie between 01 29.1 and 04 51.2, while the declination coordinates are between 30.92 ° and 59.11 ° . The International Astronomical Union (IAU) adopted the three - letter abbreviation "Per" for the constellation in 1922 . </P> <P> Algol (from the Arabic رأس الغول Ra's al - Ghul, which means The Demon's Head), also known by its Bayer designation Beta Persei, is the best - known star in Perseus . Representing the eye of the Gorgon Medusa in Greek mythology, it was called Horus in Egyptian mythology and Rosh ha Satan ("Satan's Head") in Hebrew . Located 92.8 light - years from Earth, it varies in apparent magnitude from a minimum of 3.5 to a maximum of 2.3 over a period of 2.867 days . The star system is the prototype of a group of eclipsing binary stars named Algol variables, though it has a third member to make up what is actually a triple star system . The brightest component is a blue - white main - sequence star of spectral type B8V, which is 3.5 times as massive and 180 times as luminous as the Sun . The secondary component is an orange subgiant star of type K0IV that has begun cooling and expanding to 3.5 times the radius of the Sun, and has 4.5 times the luminosity and 80% of its mass . These two are separated by only 0.05 astronomical units (AU)--five percent of the distance between the Earth and Sun; the main dip in brightness arises when the larger fainter companion passes in front of the hotter brighter primary . The tertiary component is a main sequence star of type A7, which is located on average 2.69 AU from the other two stars . AG Persei is another Algol variable in Perseus, whose primary component is a B - type main sequence star with an apparent magnitude of 6.69 . Phi Persei is a double star, although the two components do not eclipse each other . The primary star is a Be star of spectral type B0. 5, possibly a giant star, and the secondary companion is likely a stellar remnant . The secondary has a similar spectral type to O - type subdwarfs . </P>

When is the constellation perseus visible in the northern hemisphere