Sagitta, the Arrow, is the smallest of the constellations named by the ancient Greek chronicler Aratus (fourth century BCE). His account is brief: “There’s further shot another Arrow/But this without a bow.”

Despite its diminutive size, the arrow is hard to miss. Its stars are relatively bright, and it lies surrounded by the three most luminous stars in the summer sky, the aptly named Summer Triangle.

Most stargazers don’t give Sagitta a second glance. It’s not difficult to see why. The more prominent constellations nearby, not to mention the convoluted glow of the surrounding summer Milky Way, overshadow the pint-sized constellation.

However, the constellation is associated with a solemn ritual that we still practice. The rite is performed with religious fervor every four years — but I’m getting ahead of myself.

Where were we? Sagitta. Yes.

After the sky gets completely dark, look east and almost straight overhead for Vega, the brightest star of high summer, in the constellation Lyra. Deneb is down and to the left. It is the head star of the “northern cross,” also known as Cygnus, the Swan.

Completing the triangle to the right is the star Altair, easily recognizable because of the two fainter stars flanking it.

Sagitta is inside the triangle nearest to Altair. Its four brightest stars really do look like an arrow.

The two close stars on the right seem to form the notch that fits into the bowstring. Some early star maps reversed the direction of the arrow to represent the two-pointed projectile used by the Roman army.

Most of the stories about the constellation come down to us from the ancient Greeks and Romans. For example, Germanicus Julius Caesar describes the constellation as one of the arrows wielded by Cupid, the god of erotic love.

Germanicus is best known as the father of Caligula, the fourth Roman emperor of the Julian line, the grandfather of Nero, the fifth and last Julian emperor, and the older brother of Claudius, the third emperor.

The honorific title “Germanicus” was added to his name in 9 BCE because of his father’s victories against the tribes of Germany. Germanicus followed up his father’s successes with three successful German campaigns himself.

He was also something of a scholar. In 4 CE, he retold the set of constellation myths detailed in The Phenomena, written by Aratus, a Greek writer of the fourth century BCE.

(The work by Aratus was, in turn, a poetic interpretation of an earlier Greek work, now lost, by Eudoxus of Cnidus. The road these old stories travel can be long and winding.)

Germanicus reinterprets Aratus’s work to satisfy the tastes of contemporary Romans. He described Sagitta as one of the love darts used by Cupid to make people fall in “love,” although “lust” might be a more appropriate term.

Even the gods were not immune to Cupid’s arrows. Intoxicated by Cupid’s love dart, Zeus, the king of the gods, fell in lust with Ganymede, a young shepherd.

It didn’t help matters that Ganymede was a handsome young man. Homer’s “Iliad” describes him as “the loveliest born of the race of mortals.”

In the guise of an Eagle, Zeus swept down and kidnapped the unfortunate boy while he was placidly tending his sheep on Mount Ida.

Zeus offered the erstwhile shepherd several inducements to become the god’s lover and wine pourer.

One of those perks was immortality. The lowly shepherd was to become a god.

Hera, Zeus’s wife, was used to Zeus’s frequent infidelities, but the offer of immortality was over the top. Hera had viewed Zeus’s many lovers as rivals on many occasions, but the offer of eternal life turned the usual brief dalliance into a never-ending relationship.

And thus it was that Ganymede, used and abused by the gods, was transformed from shepherd to wine pourer to the constellation Aquarius, where he retains his immortality but little else.

The story seems to tell us to be wary of Cupid’s arrow, which bears the dubious gift of unadorned erotic passion. True love must bind erotic love with spiritual and emotional affinity.

In the writing of Pseudo-Eratosthenes (first century CE), Sagitta is the arrow that Apollo, the god of learning and the arts, used to slay the fierce, one-eyed Cyclops.

The tale turns on the fate of Asclepius, the son of Apollo and a mortal woman.

Asclepius developed extraordinary skills in medicine. He was so proficient in the healing arts that he could bring dead people back to life.

He became so good at raising the dead that Hades, the god of the Underworld, began to notice a dearth of wraiths entering his dark kingdom.

He asked Zeus to slay the ill-starred Asclepius. Without hesitation, Zeus dispatched the physician with one of his deadly thunderbolts.

Apollo could not control his rage. Zeus had murdered his son. He could not vent his anger on the more-powerful Zeus, so he directed his wrath at the Cyclops, who manufactured Zeus’s thunderbolts. An arrow “of great size” did the trick.

As punishment for the loss of his thunderbolt supplier, Zeus sentenced Apollo to a year’s servitude as a shepherd in Thessaly. Before he left, Apollo hid the arrow in Hyperborea, a mythical paradise, a “land beyond the North Wind,” somewhere far north of Greece.

Hyperborea was a land of perpetual sunshine, but that was not its main selling point as a hiding place. What made it a paradise was that it was the only place in heaven or on earth that was beyond the reach of the gods.

After Zeus released Apollo from his servitude, he retrieved the arrow. Demeter, the goddess of the harvest, carried it through the air and placed it in the sky for us to see to this very day.

The most common story, told by the Roman poet Hyginus in the first century BCE, has to do with that star of myth, legend, and Disney movie, the fabulous Hercules.

Hercules was the defender of the long-suffering Prometheus among his many brave deeds.

When the king of the gods, Jupiter, took over the universe, he gave Prometheus the task of creating human beings and equipping them with the tools they would need to survive on earth.

Prometheus belonged to the defeated race, called the Titans, whom Zeus and the other gods had overthrown to take over the universe. In retrospect, Zeus must have regretted giving the job to a vanquished enemy.

Without asking Zeus, Prometheus gave humans a most precious but potentially dangerous gift. He stole fire from the heavens and taught humans how to use it.

Jupiter was so angry that he took the fire back to the heavens. Prometheus had learned to love his creations so much that he risked Jupiter’s vengeful wrath and stole it back.

Hyginus tells the story of the theft this way:

“Thus, when the other gods were away, he came to Jupiter’s flame, and hiding a small part of it in a fennel-stalk, he seemed not to run, but to fly, joyfully shaking the fennel-stalk, so that the enclosed air might not extinguish the flame with its vapors in the narrow space.”

Jupiter was so enraged by the second theft of fire that he devised a cruel and horrific punishment. He chained poor Prometheus to a rock, and every day he sent a vulture to eat the liver of his screaming victim.

Every night, the liver grew back. Every day the vulture returned. Prometheus had nothing to look forward to but eternal agony.

Luckily, Hercules came to the rescue. The hero was the son of Zeus and a mortal woman. He owed, I suppose, great loyalty to his father, but his human side pitied the agonized Titan and honored him as the father of humanity. Consequently, Hercules freed Prometheus and killed the vulture with an arrow from his mighty bow.

Of course, you can see Sagitta as four tiny stars in the smallest of the constellations. However, the story of Hercules and Prometheus reminds us that the constellation is also an emblem of those characteristics that make us most human — compassion, loyalty, generosity, and honor.

Four decades back, I built my largest telescope. As is the custom of many young telescope builders, I gave the telescope a name — Prometheus because, like the ancient hero, it steals fire from the sky.

But I am not the only person who honors the memory of Prometheus. As Hyginus wrote over two millennia ago,

“And so, to this day, … following the practice of Prometheus, the custom was established that runners in athletic contests would run brandishing a torch.”

And so, to this day, the Olympic torch burns brightly every four years, and humanity again becomes the guardian of the Promethean flame.