Home >> Science & Nature >> Astronomy

How Did the Constellation Cetus the Whale Get Its Name?

Constellations -- groupings of stars that resemble an image to an imaginative stargazer -- defined harvest times and set sailing coordinates for ancient people. Over two millennia ago, Ptolemy recorded 48 of the 88 constellations that the International Astronomical Union recognizes today. The constellations along the ecliptic plane make up the zodiac; although their names appear in the daily newspaper under the horoscope section, they represent only a fraction of the night sky. Cetus, the whale, lies near Pisces.

The Sea Monster
- An ocean-dwelling cetacean shares part of its name with the constellation of Cetus the Whale.
  
  The name Cetus means "whale" in Latin, but the term's origin is older than Rome. The ancient Greeks took a name from their mythology for the massive constellation. Perseus discovered Andromeda, the daughter of Cepheus and Cassiopeia, chained to a rock as a sacrifice to a sea monster. Andromeda was to pay the price for her mother's boastfulness, but Perseus rescued the woman before the monster could devour her. That monster was Cetus. That name endures both as a constellation and as the name of the order of marine mammals: cetacea.
Mythological Connections
- A constellation's relative position tells a story along with its overall shape. The sea monster Cetus shares the sky with Cepheus, the King, and Cassiopeia, the Seated Queen. Ancient astronomers also placed Perseus, the Hero, and Andromeda, the Maiden, in the sky. When recounting the tale about the queen's boast, the hero's rescue and the fearsome sea monster, a storyteller could point to the sky as illustrations. Perseus stands next to Andromeda and between that constellation and Cetus, forever placing himself between a maiden and a monster.
"The Sea"
- Ancient and modern astronomers call the portion of the sky that Cetus occupies "the Sea" because so many of the constellations there have an aquatic theme. The massive constellation shares its area of the night sky with Pisces, the Fish; Eridanus, the River; Delphinus, the Dolphin; and Aquarius, the Water Bearer. Neighboring Capricorn also has a watery connection; it represents the Water Goat. The fourth-largest constellation, Cetus stretches across a 1,200-square-degree section of sky and borders most of the other "Sea" constellations.
The Whale
- The modern version of Cetus resembles a whale and not a sea monster on star charts and illustrations. The change happened gradually: As the original myth of Perseus and Andromeda lost its currency, sailors and whalers of later centuries saw the immense constellation in "the Sea" as a more familiar whale. Although stars change little over successive generations of stargazers, the interpretation of constellations changes to reflect what certain cultures find more relevant. To civilizations that had circumnavigated the world's oceans, a whale may have seemed a more suitable omen than a sea monster.

Astronomy