Capricornus, the goat-fish

¡SkyCaramba! Weekly astronomy blog for the week ending October 13, 2012

What strange creatures ancient civilizations often concocted in their great stories of why things are the way they are. Have you ever heard of a goat-fish? That’s what Capricornus is. That’s one of the constellations you can see in the early evenings this time of year.

To the ancient Sumerians, this constellation was Ea or Oannes, a god who brought culture and science from the sea to humankind.

The ancient Babylonians may have been the first to associate the stars of Capricornus with a goat-like creature. That was about 3,000 years ago. It’s in an area of the sky sometimes called “the water” because of the water-related constellations found there including Aquarius (the water-bearer), Eridanus (a river), and Pisces (fish). If Capricornus were only a goat, it might seem oddly placed. Perhaps that’s why it’s a goat-fish.

For the ancient Greeks, this constellation was Pan. He was a forest deity who helped the gods escape the Titans. Pan blew into a conch shell and scared the Titans away. On another occasion, Pan and the other gods were picnicking along the Nile River when a monster named Typhon came to get them. Pan suggested they turn themselves into animals and run away. But Pan himself couldn’t decide what animal to become. As he jumped into the river, he changed into a being half-goat and half-fish. His legs were in the water and became a fish tail. The rest of him was above water and became the front half of a goat.

You’ve probably heard of the Tropic of Capricorn. Yes, it’s named after the constellation Capricornus. About 2,000 years ago, the sun was in this constellation during the southern solstice. And that’s why the southernmost parallel over which the sun directly shines is called the Tropic of Capricorn. In the Far East, the constellation was called the southern gate of the sun. The name Sagittarius would be given to that line 23.5° south of the equator, if the sun’s solstice position were used to name it today.

The named stars in Capricorn have goat-related monikers. Deneb Algedi is the goat’s tail. Dabih is the lucky star of the slaughterer, and refers to an ancient practice of sacrificing goats. Baten Algiedi is the goat’s belly. Nashira is the bearer of good news. Marakk is the loins. And Giedi is the kid, a goat’s young offspring.

If you’re in the northern hemisphere, look to the south to see Capricornus in early evening, a little before 8pm local time. From about 12° to 26° south, the constellation goes overhead. South of that, look for it to the north.


The image above was made with Stellarium.