In the Sky This Month

A giant mythological soap opera stretches up the eastern half of the sky on October nights, encompassing five major constellations: Cassiopeia, Andromeda, Cepheus, Cetus, and Perseus. In the tale, Cassiopeia, queen of Ethiopia, claimed that she was more beautiful than the sea nymphs. The nymphs complained to the god Poseidon, who sent the sea monster Cetus to ravage the country. To save his people, King Cepheus chained his daughter Andromeda at the seashore as a sacrifice. At the last second, though, she was rescued by Perseus, who flashed the snake-topped head of Medusa at Cetus, turning the monster to stone.

October 20: G Stars

Under a dark sky, far from city lights, the eye can see thousands of stars, yet only a few are like the Sun. Two of them are in view by about 10 p.m. 51 Pegasi is in the south, well above the Moon. At the same time, Tau Ceti is low in the southeast.

October 21: Gibbous Moon

The Moon stands almost due east at sunset. It’s in its “waxing gibbous” phase. “Gibbous” means that sunlight illuminates more than half of the hemisphere facing Earth, while “waxing” means that a greater percentage of the surface is lit each night.

October 22: Uranus at Opposition

The planet Uranus is putting in its best showing of the year. It lines up opposite the Sun, so it rises around sunset and is in view all night. It’s brightest for the year, too, although you still need binoculars to see it.

October 23: Hunter’s Moon

The Moon will be full the next couple of nights, as it passes opposite the Sun in our sky. October’s full Moon is generally known as the Hunter’s Moon. As the full Moon after the Harvest Moon, its light helped hunters scour the barren fields for game.

October 24: M15

The globular cluster M15 is high in the southern sky at nightfall. Through binoculars, it looks like a fuzzy star. It’s actually a globe-shaped family of several hundred thousand stars that may contain a black hole at its center.

October 25: Vanishing Teapot

Sagittarius is disappearing into the evening twilight. Look for the outline of a teapot low in the south and southwest as darkness falls. The teapot is pouring its starry brew toward the horizon.

October 26: Teapot Cluster

Sagittarius, which resembles a teapot, is low in the south and southwest at nightfall. A giant star cluster lurks near the star that connects the lid and spout. Through binoculars, NGC 6624 looks like a fuzzy star. A telescope reveals many individual stars.