COSMOS / CONSTELLATIONS / CET
Cetus (Whale)
The Whale. IAU abbreviation Cet. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Cet
- Latin name / genitive
- Cetus / Ceti
- Position
- Right ascension ≈ 1 h 34 m; declination −25° to +10°
- Visibility from Türkiye
- Visible in full from anywhere in Türkiye. When it crosses the meridian its centre stands about 43° above the horizon from Ankara.
- Best time to observe
- Best placed at 21:00 Türkiye time around 11 December.
- Number of stars
- 200 stars brighter than magnitude 6.5 in the catalogue; 30 brighter than 5 and 9 brighter than 4.
INTERACTIVE LAB
Where is Cetus tonight?
The lab opens for Ankara on today’s date. Drag the time slider through the night; the “Best night” button jumps to the date when the constellation is highest at 21:00 (around 11 December). Change the city to compare the view from elsewhere in Türkiye and around the world.
MYTH, HISTORY AND OBSERVING
The sea monster sent to devour Andromeda. Omicron Ceti, known as Mira, was the first long-period variable star discovered; over about 11 months it fades from naked-eye visibility to invisibility. The Sun-like star Tau Ceti, 11.9 light-years away, and the active galaxy M77 are also here.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| Diphda | 2.04 | 96 | K0III |
| Menkar | 2.54 | 249 | M2III |
| η Cet | 3.46 | 124 | K2III |
| Kaffaljidhma | 3.47 | 80 | A3V |
| τ Cet | 3.49 | 12 | G8V |
| ι Cet | 3.56 | 275 | K2III |
| θ Cet | 3.60 | 114 | K0III |
| Baten Kaitos | 3.74 | 235 | K2III |
Magnitude: apparent brightness; the smaller the number, the brighter the star. Distances derive from parallax measurements and are uncertain for distant stars. Source: HYG v4.1 star catalogue (CC BY-SA 4.0).
SOURCES
Position, visibility and best observing time were computed approximately for this page from the catalogue stars (Ankara, 39.9° N). The 88 constellations were adopted by the IAU in 1922; their boundaries were drawn by Eugène Delporte in 1930.