This Week's Sky

Moon and Venus in early dawn, Aug 18-19, 2017

The waning Moon thins in the dawn as it heads down toward our line of sight to the Sun . . .

Friday, August 18

• As dawn begins to break on Saturday morning the 19th, look for the waning Moon hanging under Venus low in the east, as shown here. Find Pollux and Castor, much fainter, to Venus's left or upper left.

Saturday, August 19

• August is prime Milky Way time, and the dark night is now moonless. After dark the Milky Way runs from Sagittarius in the south, up and left across Aquila and through the big Summer Triangle very high in the east, and on down through Cassiopeia to Perseus rising low in the north-northeast.

Sunday, August 20

• With the Moon obviously out of the night sky getting ready for tomorrow's command performance, this would be a fine evening to look far away from the Sun into the Cygnus Milky Way, high overhead. Hunt out the telescopic deep-sky sights there that Sue French highlights in the August Sky & Telescope, page 54, with finder charts, photo, and eyepiece sketches.

Stars and Mars close to the eclipsed Sun, Aug 21, 2017

. . . which it crosses when new on Monday . . .

Monday, August 21

• In case you didn't hear, there's an eclipse of the Sun today. Not in the path of totality? You'll get a partial eclipse from anywhere in North or Central America, the Caribbean, and northern South America. Here are all our eclipse topics, including how to take photographs. Shortcut to NASA's clickable map to get your local timetable.

• If a solar eclipse is happening, you know it's new Moon today.

Tuesday, August 22

• After dusk as August nears its end, the Great Square of Pegasus looms up in the east, balancing on one corner. Its stars are only 2nd and 3rd magnitude. Extending leftward from the Square's left corner is the main line of the constellation Andromeda, made of stars about the same brightness.

This whole giant pattern was named "the Andromegasus Dipper" by the late Sky & Telescope columnist George Lovi. Shaped somewhat like a giant Little Dipper, it currently scoops upward.

Wednesday, August 23

• The actual Little Dipper, meanwhile, is tipping over leftward in the north. It's only 40% as long as the Andromegasus Dipper, and most of it is much fainter. As always, it's rotated about 90° counterclockwise from Andromegasus.

Moon and Jupiter, Aug 24 - 26, 2017

. . . and then the Moon reappears in the evening sky as a waxing crescent, retreating farther from our sunward line of sight every day. (The Moon here is positioned for the middle of North America; your aspect may vary a bit.)

Thursday, August 24

• After causing so much fuss on Monday, the Moon now gleams shyly low in the west after sunset, as shown here. Almost a fist-width to its left is Jupiter, and fainter Spica is farther left or lower left.

Friday, August 25

• Look low in the west in twilight for the waxing crescent Moon. It forms a triangle with Jupiter and Spica below it, as shown here.

Saturday, August 26

• The thickening crescent Moon, no longer so shy now, points its round side down nearly toward Jupiter low in the twilight.