The Cetus Constellation

The Cetus Constellation.

Cetus, its name refers to a sea monster in Greek mythology, although it is often called ‘the whale’ today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius, Pisces, and Eridanus. Although Cetus is not considered part of the zodiac, the ecliptic passes less than a quarter of a degree from its constellation boundary, and thus the moon, planets, and even part of the sun may be in Cetus for brief periods of time. Cetus is best viewed during December for the mid-northern latitudes at right ascension 1hour 43mins and declination -6degrees 22 mins.

Mira (“the Wonderful”), designated Omicron Ceti, was the first variable star to be discovered and the prototype of its class. Over a period of 332 days, it reaches a maximum apparent magnitude of 3 and dips to a minimum magnitude of 10. Its seeming appearance and disappearance gave it its common name, which means “the amazing one.” Mira pulsates with a minimum size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it was discovered by David Fabricius in 1596. α Ceti, traditionally called Menkar (“the nose”), is a red-hued giant star of magnitude 2.5, 220 light-years from Earth. It is a wide double star; the secondary is 93 Ceti, a blue-white hued star of magnitude 5.6, 440 light-years away. β Ceti also called Deneb Kaitos, and Diphda is the brightest star in Cetus. It is an orange-hued giant star of magnitude 2.0, 96 light-years from Earth. γ Ceti, Kaffaljidhma (“head of the whale”) is a very close double star. The primary is a yellow-hued star of magnitude 3.5, 82 light-years from Earth, and the secondary is a blue-hued star of magnitude 6.6. Tau Ceti is noted for being the nearest Sun-like star at a distance of 11.9 light-years. It is a yellow-hued main-sequence star of magnitude 3.5.

Cetus lies far from the galactic plane, so that many distant galaxies are visible, unobscured by dust from the Milky Way. Of these, the brightest is Messier 77 (NGC 1068), a 9th magnitude spiral galaxy near Delta Ceti. It appears face-on and has a visible nucleus of magnitude 10. About 50 million light-years from Earth, M77 is also a Seyfert galaxy and thus a bright object in the radio spectrum. Recently, the galactic cluster JKCS 041 was confirmed to be the most distant cluster of galaxies yet discovered. The massive cD galaxy Holmberg 15A is also found in Cetus. IC 1613 (Caldwell 51) is an irregular dwarf galaxy near the star 26 Ceti and is a member of the Local Group. NGC 246 (Caldwell 56), also called the Cetus Ring, is a planetary nebula with a magnitude of 8.0, 1600 light-years from Earth. Among some amateur astronomers, NGC 246 has garnered the nickname “Pac-Man Nebula” because of the arrangement of its central stars and the surrounding star field.Credit: Go Astronomy, Wikipedia.