Special to CosmicTribune.com, August 25, 2024

Excerpts from weekly Sky&Telescope report.

SUNDAY, AUGUST 25

■ The last-quarter Moon rises late, around 11 p.m. (It’s exactly last quarter at 5:26 a.m. Monday morning.) Spot the Pleiades a few degrees to the Moon’s upper right. Once it rises high it shines above much else in Taurus, as shown below.

■ And while you’re at it, Algol in Perseus shines two fists upper left of the Moon. Here you can catch Algol doing its famous act: It should be in one of its self-eclipses, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 3:13 a.m. EDT Monday morning August 26th; 12:13 a.m. PDT. Algol takes several additional hours to fade and to rebrighten.

MONDAY, AUGUST 26

■ As August proceeds and nights begin to turn chilly, the Great Square of Pegasus looms up in the east, balancing on one corner. Its stars are only 2nd and 3rd magnitude. Your fist at arm’s length fits inside it.

Leftward and down from the Square’s left corner extends the backbone of the constellation Andromeda: three stars in a slightly curving line (including the corner) about as bright as those forming the Square.

This whole giant pattern was named “the Andromegasus Dipper” by the late Sky & Telescope columnist George Lovi. It’s shaped sort of like a giant Little Dipper with an extra-big bowl. It’s currently lifting its contents upward.

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, you’ll find that it’s oriented more than 90° counterclockwise compared to Andromegasus. It’s dumping its contents out.

TUESDAY, AUGUST 27

■ “This is my 100th column,” writes Binocular Highlights columnist Matt Wedel in the September Sky & Telescope, “and to celebrate I’m going to revisit my all-time favorite target: the heart asterism at the center of Cygnus, the Swan.” That was a new one on me. Could he mean the ragged ring of binoculars stars around Gamma Cygni, the center star of the Northern Cross? Well, that’s part of it. Judge for yourself. He explains it on page 43 of the September issue, with a chart, in “Where the Secrets Are Kept.”

WEDNESDAY, AUGUST 28

■ Arcturus is the brightest star high in the west on late-summer evenings. In astronomy lore nowadays, Arcturus may be best known for its cosmic history: It’s an orange giant some 7 billion years old, older than the solar system, racing by our part of space on a trajectory that indicates it was born in another galaxy: an ancient dwarf galaxy that fell into the Milky Way and merged with it.

Arcturus was famous as one of the first stars discovered to show proper motion, its own independent motion on the celestial sphere. In 1718 Edmond Halley realized that Arcturus, Sirius, and Aldebaran had moved more than half a degree from where the Greek astronomer Hipparchus had carefully measured them to be some 1,850 years earlier.

And before that? Arcturus was the first nighttime star to be seen in the daytime with a telescope: by Jean-Baptiste Morin in 1635.

THURSDAY, AUGUST 29

■ As summer progresses and Arcturus moves down the western sky, the kite figure of Boötes that sprouts up from it tilts to the right. The kite is narrow, slightly bent, and 23° long: about two fists at arm’s length. Arcturus is its bottom point where the stubby tail is tied on.

The Big Dipper now slants at about the same height in the northwest, to the Kite’s right.

FRIDAY, AUGUST 30

■ Venus, still very low in the west-southwest in bright twilight, has been creeping up very slightly day by day, while springtime Spica, barely a hundredth as bright, is finally sinking away for the year.

Venus and Spica will pass each other on September 17th.

Venus low in twilight and Spica, vastly fainter and not much higher, are now 22° apart: about two fists at arm’s length. Good luck. The farther south you are the better. These scenes are always plotted for a skywatcher at north latitude 40°. So, if you’re much south of there Venus will be a trace higher than shown and Spica will be substantially more so.

SATURDAY, AUGUST 31

■ Late these evenings as autumn approaches, Fomalhaut, the Autumn Star, makes its appearance above the southeast horizon. Its rising time will depend on where you live. Watch for it to come up two fists to the lower right of first-magnitude Saturn. By 10 or 11 p.m. you should have no trouble spotting Fomalhaut low in the southeast if you have a view in that direction.

■ As dawn brightens on Sunday morning September 1st, look east-northeast for the hairline crescent Moon with Mercury 4° to its right, as plotted below. Binoculars will help in the brightening sky.

SUNDAY, SEPTEMBER 1

■ A sign of the advancing season: Cassiopeia is now high in the northeast after dark, its W pattern tilting up. And below it, starry Perseus is reaching up.

The highest part of Perseus includes the wintry Double Cluster. To find it, look back to Cassiopeia. Counting down from the top, note the third segment of the W. Continue that segment downward by twice its length, and there you are.

You’re looking for what seems like a small spot of enhanced Milky Way glow. Binoculars or a finderscope will help you detect the Double Cluster even through a fair amount of light pollution. The pair are a glory in a telescope.

  August 25 – September 1; Summer winds down, double cluster on the rise, The Sky