The Helix Nebula, NGC 7293, is one of the closest known planetary nebulae, roughly 650 light-years from Earth. It formed when a Sun-like star reached the end of its red-giant phase and expelled its outer layers into space, leaving behind a hot white-dwarf core whose ultraviolet radiation makes the expanding gas glow.

Its familiar eye-like appearance is only part of a much larger three-dimensional structure. The bright inner ring is surrounded by fainter arcs and halos of older material, while thousands of dense cometary knots point away from the central star. Those knots are small on astronomical scales, but each can span distances comparable to the size of the Solar System.

Because the Helix is both nearby and physically large, it spreads its light across a broad patch of sky. That makes it impressive in deep photographs but surprisingly subtle visually: under dark skies it appears as a large, ghostly disk rather than the compact bright ring seen in smaller planetary nebulae such as M57.

The Helix lies in Aquarius, the Water-Bearer, one of the oldest constellations associated with water and the seasonal rains. In the best-known Greek tradition Aquarius represents Ganymede, a beautiful Trojan prince carried to Olympus by Zeus and made cupbearer to the gods.

Ganymede was given the task of pouring the gods' drink, and the constellation is traditionally shown tipping a vessel whose stream flows toward the southern sky. The nearby constellations Pisces, Cetus and Eridanus helped ancient skywatchers imagine this whole region as a great celestial sea.

The Helix Nebula itself is far too faint to have been part of ancient mythology, but its enormous circular glow sits naturally inside that water-themed region of the sky. Modern astronomy gives the old Water-Bearer a very different kind of vessel: the expanding remains of a star returning its material to interstellar space.