Special to CosmicTribune.com, August 21, 2023, 2023

Excerpts from weekly Sky&Telescope report.

MONDAY, AUGUST 21

■ Different people have an easier or harder time seeing star colors, especially subtle ones. To me, the tints of bright stars stand out a little better in a sky that’s the deep blue of late twilight.

For instance, the two brightest stars of summer are Vega, nearly overhead at that time, and Arcturus shining in the west. Vega is white with just a touch of blue. Arcturus is pale yellow-orange.

Vega is a white-hot, type-A star 25 light-years away. Arcturus is a less hot, type-K giant 37 light-years distant.

TUESDAY, AUGUST 22

■ 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, and your fist at arm’s length fits inside it.

From the Square’s left corner extends the main line of the constellation Andromeda: three stars (including the corner) running lower leftward. They’re as bright as those forming the Square itself.

WEDNESDAY, AUGUST 23

■ First-quarter Moon this evening and tomorrow evening (exactly first-quarter at 5:57 a.m. EDT Thursday morning, which splits the difference between those two evenings for the Americas). This evening the Moon is low in the southwest after dark, to the right of Antares and the head of Scorpius.

THURSDAY, AUGUST 24

■ Moon occults Antares. Now the Moon shines near 1st-magnitude Antares as seen from the Americas , as shown — and the Moon will occult Antares for much of the continental United States and southern Canada.

For the northeastern seaboard, the Moon will be very low over the southwest horizon at the time of Antares’s disappearance behind its dark limb. In most of the West, the sky will still be bright or even full daylight. But everywhere in between, this will be the best lunar occultation of a star in quite a while!

The occultation is grazing for parts of north-central Florida, with Antares skimming the mountains and valleys along the Moon’s southern limb.

FRIDAY, AUGUST 25

■ How soon after sunset can you see the big Summer Triangle? Face east. Vega, the Triangle’s brightest star, is nearly at the zenith (for skywatchers at mid-northern latitudes). Deneb is the first bright star to Vega’s east-northeast. Altair shines less high in the southeast.

SATURDAY, AUGUST 26

■ Saturn is at opposition tonight (exactly so at 4 a.m. on the 27th EDT). In a telescope, do you notice that Saturn’s rings are distinctly brighter, compared to Saturn’s globe, than you usually see them? This is the Seeliger effect, caused by the solid ring particles backscattering sunlight to us when the Sun is almost directly behind us. The dusty surfaces of the Moon and Mars also display this “opposition effect,” but Saturn’s clouds do not. In the case of Saturn the effect is named for Hugo von Seeliger, who studied it in detail and published his findings in 1887.

The brightening begins several days before Saturn’s opposition, is strongest right around that date, and fades for several days after.

SUNDAY, AUGUST 27

■ The waxing gibbous Moon shines in the south after dark. High above it, by three or four fists at arm’s length, spot 1st-magnitude Altair with its little sidekick, 3rd-magnitude Tarazed (Gamma Aquilae) about a finger-width above it.

Much closer to the right of the Moon is the Sagittarius Teapot. Its four-star handle is the part closest to the Moon, less than a fist at arm’s length. About a fist right of the handle, and perhaps a bit lower, is the Teapot’s spout. Binoculars help through the moonlight.

  The sky: August 20-27; Moon occults Antares on August 24