In the Sky This Month

Today is Halloween, an astronomical cross-quarter day. Such dates occur roughly half way between an equinox and a solstice. In many calendars, such a date marked the beginning of a season, not its middle.

For the second time this month, the Moon is at last quarter. It is three-fourths of the way through its cycle of phases, headed toward “new” on November 7. There’s no special name for two quarter moons in the same month.

One of the prime stars of summer continues to dazzle in the autumn sky. Vega is quite high in the west at nightfall. It’s the brightest member of the Summer Triangle.

The planet Mars stands about a third of the way up the southern sky at nightfall, shining like a bright orange star. It sets in the wee hours of the morning.

One sure sign of autumn is the early evening appearance of Cetus, the whale or sea monster. As befits a whale, Cetus is huge, but its stars are faint and difficult to see. Cetus climbs into view in the southeast a few hours after sunset.

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.

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.

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.

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.

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.