Look south just after dark. If your sky is clear of haze and clouds, you will see one of the most important, if inconspicuous, constellations in the nighttime sky. Capricornus, the Sea Goat, looks a bit like a gaping, toothless grin. However, since ancient times, most stargazers associated it with a goat, of all things.

And a strange goat it is. For millennia, artists and writers have portrayed it with the head and torso of a goat and the tail of a fish.

Even some seasoned stargazers cannot identify the constellation. Its stars are exceedingly faint as constellation stars go. It has little to offer as far as telescopic objects are concerned. None of its stars shine with any brilliancy of color.

What gives? Why is such an inconspicuous constellation so important? What in heaven’s name is a sea goat, anyway?

Read on, gentle stargazers, and you will see what you have been missing all these years.

Capricornus lies along the Zodiac, the band of constellations through which the sun, moon, and planets move as they appear to traverse the starry background. The sun appears in Capricornus from about Jan. 16 to Feb. 12 as you astrologists out there may know.

The faint Sea Goat occupies the Zodiacal sky between the much brighter constellations Aquarius and Sagittarius. Because of its Zodiacal location and despite its inconspicuousness, Capricornus has remained unchanged since the dawn of recorded western history. It may even have originated in prehistoric times.

Why? In ancient times, the sun was in Capricornus when it reached the winter-solstice point on or around Dec. 21, the shortest day and the longest night of the year. (These days, the solstice occurs in the constellation Sagittarius because of Earth’s slow wobble on its axis.)

Before the solstice, the sun is moving downward from the horizon. At the solstice point, the sun seems to stand still for a moment. After the solstice, it appears to rise higher every day.

The constellation’s association with the solstice dates back to the Akkadian culture, which flourished in Mesopotamia between 2334-2154 BCE. They called their 10th month, the solstice month, “the cave of the rising” of the sun. During that month, the sun began to rise out of the dark and dreary realm of the dead, the “blind cave of eternal night,” as Shakespeare described it much later in Richard III.

The solstice moment had a dual meaning to our forebears. On one level, the sun is reborn — the “birthday of the new unconquered sun,” as constellation historian Julius Staal describes it.

According to William Olcott, the constellation’s solstice position caused the ancient Greeks to consider it “The Gate of the Gods” through which the souls of the dead pass.

On another level, the solstice marks the beginning of winter with its harsh cold and dangerous storms. Capricornus thus becomes the harbinger of both good fortune and winter’s deprivations because of the sun’s position within its boundaries.

So how is a goat involved? Roman author Macrobius, who wrote around 400 CE, claims that the Chaldean civilization, which occupied Mesopotamia between the late 10th or early ninth through the mid-sixth centuries BCE, called the constellation the “Wild Goat.” Just as mountain goats ascend the mountains as they feed, so too does the sun begin to climb in the sky when it is in the “Wild Goat” constellation.

Thus, Aratus, a Greek poet and constellational climatologist of the third century CE, calls the constellation the “Horned Goat.”

However, Aratus did not see it as a favorable constellation because it marked the first day of winter. Although he never mentions the Sea Goat’s tail, he does connect the constellation with the sea. He writes, “The grievous blasts/Break southward on the sea, when coincide/The Goat and sun; and then a heaven-sent cold.”

The strange combination of a goat with a fish’s tail is harder to trace. William Olcott argues, somewhat dubiously, that Egyptian astronomers associated the constellation with “the god of the waters,” who made the Nile River overflow its banks and carry the fertile soil so necessary to Egyptian survival. Olcott also claims that the constellation is a representation of the goat-god Mendes in the Egyptian Zodiac.

A Mesopotamian origin is less problematic. During the 16th­–12th centuries BCE, the Babylonian culture, which dominated Mesopotamia during the period, had a “fondness for amphibious creatures” like sea goats, as Ian Ridpath points out.

The Babylonians erected Kudurru, stone and clay tablets meant to mark the boundaries of land ownership. The constellation Capricornus appears on some of those stones. The depiction is more or less identical to the Capricornus we see today.

The Sumerians, who predate the Babylonians in the region by 1,000 years, called the constellation SURUR-MASH-HA, the “Goat Fish.”

We can be even more confident of a later Greek connection. The goat association was firmly established by the time of the classical Greeks, who named Capricornus, Aegoceros, which translates as “goat-horned.” His fishy tail is somewhat more problematic, as we shall see.

The Greeks identified the constellation with their pastoral god Pan. He seems to have spent most of his waking time pursuing mortal women and nymphs or, as Ian Ridpath puts it, “sleeping it off” afterward.

He was reputed to be a trickster and somewhat impulsive.

But he was also fond of his afternoon siestas. When awakened abruptly, he shouted with displeasure, alarming nearby listeners into a “panic.” (Yes, that’s where we get the word.)

He was the master of rustic music. A few modern musicians still play his favorite musical instrument, the Pan pipes.

Pan had an upper body that looked quite human. However, he had goat-like horns and the legs and buttocks of a mountain goat. The fish’s tail is notably missing.

Greek and Roman commentators had to jump through several narrative hoops to preserve the connection between Pan and the fishy tail of Capricornus.

As with many constellation stories, the Pan-Capricornus connection begins with the battle between the gods and Titans for universal supremacy.

During the battle, the Titan Gaea (Mother Earth) sent the monstrous Typhon against the gods. Sometimes, Greek myths describe Typhon with a winged, human-like body and 100 fire-breathing heads. Every so often, it is entirely serpentine, a full-fledged, fire-breathing dragon. In any case, Typhon was a formidable foe.

Characteristically, Pan shouted at the top of his considerable lungs to warn the gods about the approaching monster.

They knew they couldn’t defeat Typhon. So Pan suggested that they disguise themselves as animals and run away.

Pan jumped into a river, gave himself a fish’s tail, and swam away.

At that point, Zeus, the most powerful of the gods and consequently their king, rushed to the rescue. But Typhon was strong enough to cripple Zeus by pulling the ligaments out of his legs.

With the help of Hermes, a fellow trickster and messenger of the gods, Pan magically restored the ligaments. Zeus chased after the fleeing monster and killed it with his famous thunderbolts.

Zeus buried Typhon under Mount Etna, which still spews the monster’s fiery breath to this very day.

The sea-goat characterization thus rests upon Pan’s brief time with a fish’s tail as he swam away in terror from Typhon. No matter that he lost his goat legs. His horns presumably remained.

Two variations of the story also attempt to explain the constellation’s “Sea Goat” designation. Both of them seem, well, fishy, even by the standards of Greco-Roman mythology.

Eratosthenes, a Greek poet, astronomer, and mathematician of the third century BCE, states that Pan blew a conch shell to frighten the Titans into a hasty retreat. About two centuries later, Hyginus, a Roman commentator, writes that Pan hurled shellfish at the Titans.

Hyginus’s story is strange, at best. One has to doubt that the mighty Titans quaked with fear as a sizeable number of shrimp, lobsters, and clams flew their way. Pan was impulsive, but he wasn’t stupid.

Neither explanation adequately explains Capricornus’s fishy posterior. The Greek and Roman commentators seem to be interpolating story elements to justify the popularly held sea-goat characterization.

In any case, the boisterous Pan had saved the day by quick-witted guile and decisive, if impulsive, action. Zeus expressed his gratitude to Pan by placing his image in the sky as the goat-fish Capricornus.

And there the matter stands to this very day.