Even on a dark, moonless night, away from the glow of the city, some regions of the sky look dark and empty. One of those regions is the celestial sea — a connected set of constellations with aquatic themes. It ripples across the south on autumn nights.

Right now, the most prominent member of the sea is Capricornus, the sea goat — but not because of the constellation itself. Instead, the giant planets Jupiter and Saturn are passing across it.

Some of the stars of Capricornus outline a wide triangle, which is in the south at nightfall. Jupiter is at the left point of the triangle, and looks like a brilliant star. Saturn is at the right side of the triangle. Saturn isn’t as bright as Jupiter, but still brighter than the stars around it.

Faint Aquarius is to the left of Capricornus, with Piscis Austrinus, the southern fish, below them. It contains the brightest true star in the entire sea: Fomalhaut, the autumn star.

Pisces, which represents two fish tied together by their tails, stretches from southeast to east. Like Aquarius, it’s especially faint, so you need dark skies to see just about any of its stars. And below it, Cetus, the whale or sea monster, is surfacing into view.

One more watery constellation flows into view later on: Eridanus, the river. It consists of a winding trail of stars that extends all the way to the corner of Orion — a bright constellation that will highlight the bright night sky of winter.
 

Script by Damond Benningfield

Support McDonald Observatory