In the Sky This Month

The planet Mars stands close to the Moon tonight. It looks like a bright orange star to the left of the Moon in early evening, and above the Moon as they set, before dawn.

Cassiopeia A is an exploded star in the constellation Cassiopeia, which is high in the northeast at nightfall. The star is surrounded by filaments of oxygen, iron, sulfur, and other elements. They were forged inside the star or in the blast that ripped it apart.

The brightest stars of Cassiopeia form one of the most prominent patterns in the night sky — a big letter M or W. It’s in good view in the northeast this evening, and wheels high across the north during the night.

The bright yellow-orange star Capella climbs into good view in the northeast by 8 or 9 p.m. The system consists of two stars that are bigger and heavier than the Sun. And even though they are much younger than the Sun, they’re already near the ends of their lives.

Hamal, the brightest star of Aries, is low in the east as night falls, far to the left of bright orange Mars. The star is a billion years younger than the Sun. Yet it’s past the end of its “normal” lifetime — a point the Sun won’t reach for five billion years.

The Moon is at first quarter today. It rises in the 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.

The planets Jupiter and Saturn cozy up to the Moon tonight. Jupiter is to the upper right of the Moon and looks like a brilliant star. Right now, only Venus and Mars outshine it. Saturn is above the Moon. It looks like a bright star, but not nearly as bright as Jupiter.

The Moon and the solar system’s two largest planets line up in the south and southwest as night falls. Jupiter and Saturn stand to the upper left of the Moon. Jupiter is far brighter than Saturn and is closer to the Moon.

The Orionid meteor shower should be at its best tonight. It takes place as Earth flies through the path of Comet Halley. The comet sheds rock and dust as it orbits the Sun. These bits vaporize as they hit our atmosphere, forming streaks of light known as meteors.

Antares looks up at the Moon in early evening twilight. The orange star stands at the heart of Scorpius. The scorpion’s head is to the right of Antares, with its body and stinger to the left. They are quite low in the sky, so binoculars will help you find them.