Special to CosmicTribune.com, September 1, 2024

Excerpts from weekly Sky&Telescope report.

The thin waning crescent Moon guides the way to Mercury low in bright dawn on the mornings of August 31st and September 1st. Bring binoculars.

SUNDAY, SEPTEMBER 1

■ Look for bright Vega passing the zenith as twilight fades away, if you live in the world’s mid-northern latitudes.

■ Another 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 upward.

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.

MONDAY, SEPTEMBER 2

■ As September begins to take hold and nights grow chilly, the Great Square of Pegasus displays itself in the east, balancing on one corner. Its stars are only 2nd and 3rd magnitude. Your fist at arm’s length fits inside it.

From the Square’s left corner, leftward or lower-leftward extends the backbone of the constellation Andromeda: three stars in a slightly curving line (including the corner) that are about as bright as those forming the Square.

■ New Moon today (exact at 9:36 p.m. EDT).

TUESDAY, SEPTEMBER 3

■ The coming of September also means that Scorpius, the proudly starring highlight of the southern sky during July, is now tilting over and lying down in the southwest after dark, preparing to bed down and drift off for the season.

WEDNESDAY, SEPTEMBER 4

■ Find little Sagitta the Arrow barely a fist at arm’s length above bright Altair high in the south these evenings. If your light pollution is too much, use binoculars.

Now imagine rotating the Arrow on its point a third of a turn counterclockwise. Its middle star would now rest just barely (0.4°) below M27, the big Dumbbell Nebula. At a total magnitude of 7½, the Dumbbell is a largish but subtle gray glow nearly 0.1° wide, easily seen in binoculars or a finderscope under a dark sky. In a 4- to 8-inch telescope it’s a rectangle or hourglass. It’s the brightest planetary nebula in the sky if you sum up all its spread-out light.

The Dumbbell Nebula, M27. This view is 0.9° wide, about the width of a 60-power field of view in a typical telescope eyepiece. North is up, east is left. The star 14 Vulpeculae is magnitude 5.6.The star HD 189733, magnitude 7.7, is a yellow-orange K dwarf 63 light-years away from us, notable for having a hot-Jupiter exoplanet very closely orbiting it. The nebula is far in the background: about 1,360 light-years away.

By the way, the odd name Dumbbell Nebula was bestowed by John Herschel in 1828.

A much more recent name for M27, more accurate to modern eyes, is the Applecore Nebula. The earliest use of this name that I find in print using Google Books is from 1997.

THURSDAY, SEPTEMBER 5

■ Starting about 15 or 20 minutes after sunset, look very low a little left of west for Venus and the two-day-old crescent Moon, as shown below. They’re roughly 7° apart at dusk for North America. Binoculars help bring them out through bright twilight. They set before twilight ends.

As the afterglow of sunset starts to fade early Thursday evening, try for the thin crescent Moon with Venus to its right very low in the west-southwest by west.And with binoculars, can you still make out Spica?

FRIDAY, SEPTEMBER 6

■ Now the thickening crescent Moon shines about 18° (nearly two fists) left or upper left of Venus in bright twilight. And Spica is now partway between them, as shown above.

■ Then several hours later as dawn in getting under way on Saturday the 7th, Mercury poses low over much fainter Regulus, as shown below.

SATURDAY, SEPTEMBER 7

■ A winter preview: Step out before the first light of dawn this week, and the sky displays the same starry panorama it will at dinnertime around New Year’s. Orion is striding up in the southeast, with Aldebaran and then the Pleiades high above it. Sirius sparkles far down below Orion. The Gemini twins are lying on their sides well up in the east.

■ Mercury-Spica conjunction: Then stay up until dawn is well under way, and with an open view low to the east-northeast by east, catch Mercury on the rise. Use optical aid to try to pick up Spica now in conjunction with it, 0.5° to Mercury’s right (for the time of dawn in North America). They’ll both fit in the same low-power field of a small or medium-size telescope.

SUNDAY, SEPTEMBER 8

■ At nightfall, the crescent Moon shines low in the southwest. Look almost two fists upper left of it for orange Antares.

Two thirds of the way from the Moon to Antares is the near-vertical row of three stars marking the head of Scorpius. The brightest of these three is the middle one, Delta Sco. It’s not all that much fainter than Antares.

  September 1-8: A winter preview at dawn, The Sky