In the Sky This Month

Look high in the north and east during the evening hours this month for a flattened “W” or “M” floating through the Milky Way. The letter is outlined by five bright stars that mark the constellation Cassiopeia, the queen.

Taurus, the bull, is climbing higher into the evening sky this month. It is in view in the east by about 9 p.m., but is well up in the sky a couple of hours later. Look for its V-shaped head and its bright orange “eye,” the star Aldebaran.

A “spooky” star system in Perseus is one of the highlights of the Halloween sky. Two of its stars eclipse each other, causing the system to get fainter every three days. Early skywatchers found this frightening, so they named it Algol, the Demon Star.

The brightest star of the constellation Perseus befits the celestial hero. Mirfak is seven or eight times heavier than the Sun, about 60 times wider, and 5,000 times brighter. That makes it easy to see even though it is more than 500 light-years away.

The Moon is sailing across the “celestial sea,” a group of constellations related to water. By about 11 p.m. the sea will span the entire southern sky. It incorporates a sea-goat, the water bearer, the fishes, the southern fish, a sea monster, and a river.

A beautiful Moon slides across the southwestern sky this evening, in Capricornus. It is a day past first quarter, so the Sun illuminates more than half of the lunar hemisphere that faces our way. The Moon sets about 1 or 2 a.m.

The Moon is at first quarter today. It rises in early afternoon and sets around midnight. At first quarter, sunlight illuminates exactly half of the lunar hemisphere that faces Earth, so it looks as though someone sliced the Moon down the middle.

One of the treasures of the constellation Andromeda, which is low in the east and northeast at nightfall, is the Blue Snowball Nebula, a bubble of gas expelled by a dying star. The nebula is at the right edge of the constellation, above the Great Square of Pegasus.

Andromeda, the princess, is in the east and northeast at nightfall. It’s faint, though, so you need dark skies to see it. Andromeda is associated with several other constellations that share a common story.

Saturn, the solar system’s second-largest planet, huddles to the lower right of the Moon at nightfall this evening. Saturn has the largest ring system of any of the Sun’s planets, and the second-largest known retinue of moons.