In the Sky This Month

If you can find an especially dark skywatching site as night falls, you’ll see the Milky Way arcing from teapot-shaped Sagittarius in the south, through the swan high in the east, and over to W-shaped Cassiopeia in the northeast.

The Dog Days of summer are either in full swing or just wrapping up. That’s because there’s no definition for the dates of the Dog Days. All we can say for sure is that they got their name from Sirius, the Dog Star, the brightest star in the night sky.

Cassiopeia circles up across the northeastern sky this evening. The queen’s brightest stars form a letter W, making the constellation easy to find. All five of the stars in that pattern are much bigger, heavier, and brighter than the Sun.

The celestial scorpion curves above the southern horizon as night falls, with bright orange Antares as its heart. Faint Sigma Scorpii, to the right of Antares, consists of four stars, at least one of which will end its life as a supernova.

The Moon will be full tomorrow at 7:29 a.m. CDT, as it lines up opposite the Sun. The full Moon of August is known as the Grain Moon, Green Corn Moon, or Sturgeon Moon.

The planet Venus is passing behind the Sun as seen from Earth, so it is hidden from view. It will return as the brilliant “evening star” in October, with the exact date depending on your latitude.

Stars twinkle because Earth’s atmosphere bends their light. Different colors bend at different angles, so twinkling stars flash different colors. Twinkling also spreads a star’s light, turning it into a fuzzy blob when viewed through a telescope.

The Moon tonight sets its sights on the second-biggest planet in the solar system. Saturn looks like a bright star to the left of the Moon as darkness falls. It will stand even closer above the Moon as they set in the wee hours of the morning.

The Perseid meteor shower will be at its best the next few nights. This “rain” of comet dust has put on some good shows over the years, but this year’s won’t be one of them. The Moon will overpower all but its brightest “shooting stars.”

The planet Jupiter, which looks like a brilliant star, stands quite close to the lower right of the Moon this evening. The bright orange star Antares, the heart of the scorpion, is farther along the same line.