For those of us in the northern hemisphere, September is an excellent time to search for the faint constellation of Capricornus, the sea goat, one of the oldest recognised constellations. It appears on Ptolemy’s second-century list of 48, and even before that on Babylonian clay tablets that date from a few thousand years BC.
Capricornus is depicted to be a chimera, a mythical creature containing the body and head of a goat and the tail of a fish. In Greek mythology it is often associated with Amalthea, who hid the young Zeus from his child-devouring father, Cronos, or Pan the shepherd god.
The constellation straddles the ecliptic, the annual path of the sun through the sky, which means it is one of the 12 constellations of the zodiac.
The chart shows the view looking south from London at midnight as 1 September becomes 2 September. The brightest star in the constellation is Deneb Algedi. Locate this and then work your way around the constellation. Pause when you get to the star Algedi and see if you can make out its fainter companion, situated in close attendance.
From the southern hemisphere, Capricornus appears much higher in the north-western sky.
