Constellation Data

Name: CETUS Translation: Whale or sea monster Abbreviation: Cet Genitive: Ceti Size: 4 RA: 2 hours Decl: -10 degrees Season: Fall Midnight Culmination: October 15 Pages where CETUS is discussed in Chet Raymo's 365 Starry Nights: 61,97,98,184,198-199,217

What is the Genitive form? What is Right Ascension (RA)? Is this constellation ever visible from my latitude? What is Declination? Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination?

Skylore

Killed by Perseus as he was attempting to devour Andromeda.

Description

South of Aries and Pisces, one of the largest constellations. Trace to the second-magnitude star Beta-Ceti (Diphda, near the flukes) by following a line southward from Alpheratz (the corner of Pegasus and Andromeda) through gamma-Pegasi, across Pisces and Cetus.

Legend: In the constellation chart above...
• Star colors represent their spectral types (even for double stars).
• Bright star labels are yellow; significant other stars are labelled in magenta.
• The size of each star indicates its relative magnitude.
• Constellation names are light blue.
• Grid lines represent either 10 degree intervals of declination above or below the equator, or intervals of one hour (=15 degrees) of right ascension (measured along the equator).
• Messier object numbers are pink.
• Galaxies are ovals: blue if spiral, yellow if elliptical, light blue if irregular.
• Globular clusters are gold starbursts.
• Open clusters are dotted white circles.
• Planetary nebula are green diamonds.
• Bright nebula are magenta squares.
• Dark nebula are grey rectangles.
• Green x's are x-ray sources.
• Purple O's with a diagonal slash through them are quasars.

Special Stars

Alpha-Ceti or Menkar is a red giant located in the whale's head.

Mira lies very close to the brightest star of Pisces (the "knot" holding the two fish together). Hevelius named it Mira, which means marvellous or miraculous, because it was the first star to be recognized as varying in brightness (1596). Mira is visible only for a few weeks each year. Its period is 332 days, during which time it remains usually near the 9th magnitude, too faint to see. Then it brightens to magnitude 1.7, becoming the brightest star in Cetus! Mira shines with a deep reddish tint; as a red giant (like Aldebaran in Taurus) it is massive, and would contain the orbit of Mars. Declination: -3 degrees south.

UV Ceti, which is actually a pair of very dim red dwarf stars (A and B), lies only 8.4 LY away--the fifth closest star system. UV Ceti B is a flare star, and varies from 13th magnitude (not visible to the naked eye) to the 6th magnitude, 250 times brighter (in 1952 this flare-up occurred in only 21 seconds). Why some red dwarfs flare in this way is not known.

Tau-Ceti is the 20th closest star, and the closest solar-type star, which makes it a favorite candidate in the search for extra-terrestrial life. Very few naked-eye stars are dimmer than the Sun, but the luminosity of Tau-Ceti is 0.45 (Sun = 1). Magnitude 3.5. Distance: 11.8 LY.

Table of 25 Brightest Stars.
What is apparent stellar magnitude?

Nebulae

M77 (NGC1068), spiral galaxy, viewed face-on.

What are Nebulae?
Table of Messier Objects.
What is apparent Magnitude?

Galaxies

M77 (Spiral galaxy), mag. 8.9. Although this galaxy is not especially impressive through a telescope, it is exceptionally massive, and may contain a giant black hole in its core.

What are Galaxies?
Table of Messier Objects.
What is apparent Magnitude?

Discussed in these Shows

©1997 Welcome to the Basic Celestial Phenomena web site. To provide explanations of basic observational astronomy to students, teachers, families, and visitors to planetariums these pages have been written by an ex-OBU Planetarium Director, Kerry Magruder; the OBU Natural Sciences Coordinator, Mike Keas; and some of the students who work in the OBU planetarium.

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