Capricorn Constellation

Capricorn — formally Capricornus — is the faintest constellation of the zodiac after Cancer, a modest triangle of stars representing a peculiar hybrid creature: the Sea-Goat, part mountain goat and part fish. The image dates back thousands of years to Babylonian astronomy, where it was known as "the Goat-Fish," and it later became linked in Greek myth to Pan, the goat-legged god who leapt into a river and was transformed to escape a monster. Though faint, Capricorn has genuine historical weight, once marking the point where the Sun reached its southernmost point in the sky — which is why Earth's Tropic of Capricorn still carries its name.

Capricorn at a Glance

• AbbreviationCap
• Genitive FormCapricorni
• MeaningThe Sea-Goat
• Constellation FamilyZodiac
• Area414 sq. degrees (40th largest of 88)
• Right Ascension20h 06m – 21h 59m
• Declination-8.4° to -27.7°
• Brightest StarDeneb Algedi (magnitude 2.85)
• Best Evening ViewingSeptember, visible 60°N to 90°S
• Sun's Actual TransitJanuary 20 – February 16 (astrology: December 22 – January 19)

Mythology and History

The most common Greek myth behind Capricornus involves Pan, the god of the wild, shepherds, and rustic music, who was attending a feast of the gods on the banks of the Nile when the monstrous Typhon suddenly attacked. In his panic to escape, Pan dove into the river and tried to transform himself into a fish, but the spell only half worked — leaving him with the head and torso of a goat and the tail of a fish. Zeus, amused by the sight, placed the strange hybrid form among the stars. The image is actually far older than the Greek myth attached to it: Babylonian astronomers recorded a goat-fish figure, associated with the god Enki, in their star catalogues more than a thousand years before Ptolemy listed Capricornus among his 48 constellations in the 2nd century AD.

Notable Stars in Capricorn

Deneb Algedi, the brightest star in Capricornus at magnitude 2.85, is an eclipsing binary system roughly 39 light-years from Earth whose two component stars periodically pass in front of one another, causing small, regular dips in brightness. Its name comes from Arabic for "tail of the goat." Algedi, marking the goat's head, is actually a naked-eye double star — two unrelated stars that happen to appear close together from Earth, easily split without any equipment on a clear night.

Deep-Sky Objects

Capricornus is not rich in bright deep-sky objects, but M30, a dense and compact globular cluster of ancient stars roughly 27,000 light-years away, is a satisfying target for small telescopes and one of the constellation's few Messier entries.

• M30 — a compact, dense globular cluster of ancient stars roughly 27,000 light-years away, visible in small telescopes

Neighboring Constellations and How to Find It

Capricorn's faint triangular shape sits between Sagittarius and Aquarius, low in the southern sky during autumn evenings. It's easiest to find by first locating the brighter Sagittarius Teapot and scanning eastward; Capricorn reaches its highest point around September. Capricorn borders Aquarius, Aquila, Sagittarius, Microscopium, and Piscis Austrinus.

Capricorn is also associated with the Alpha Capricornids, Chi Capricornids, Sigma Capricornids, and Tau Capricornids meteor showers, visible to observers who track where these annual displays radiate from.