This is the Skywatch Line for Monday and Tuesday, September 30th and October 1st, written by Joe Slomka.
The Sun sets at 6:39 PM; night falls at 8:13. Dawn breaks at 5:18 AM and ends with the Sun rising at 6:52.
Mercury and Venus are challenge objects just after sunset, southward of the Sun; Mercury is about 12 to the Moon’s lower right. Mercury is about 85% lit and shines with minus 2nd magnitude. Venus blazes with minus 4th magnitude, but much closer to the horizon. Since both are within the setting sun’s glare, binoculars are recommended; but observers are warned to carefully avoid looking at the Sun. Both set by 7:16 PM. If unsuccessful on these nights, both planets are will be higher and easier daily all October.
Jupiter and Saturn continue to be the only easily observed planets in the evening sky. Jupiter remains in Ophiuchus, glaring with minus 2nd magnitude and hovering about 20 above the horizon. It sets at 9:58 PM.
Saturn, in Sagittarius, glows with zero magnitude and lies about 24 high, it too is fairly low. However, Saturn is still worth turning a telescope on it. Saturn is nearing eastern quadrature, which means it appears 90 east of the Sun. The fact that the rings are tilted 25 to us, and with the Sun’s light shinng on the equator, the observer should experience an almost 3-D view. Saturn sets at 11:54 PM.
The Moon inhabits Libra on both nights. Monday’s 3-day-old Moon appears about 7% lit and flashes with minus 4th magnitude. Tuesday’s Moon appears fatter and brighter. It sets at 8:10 PM on Monday and at 8:44 PM on Tuesday.
Neptune continues to occupy Aquarius, shining with 8th magnitude and appearing as a tiny 2 arc-second dot. It is best observed at 11:30 PM and sets at 5:09 AM. Uranus is still in Aries, brighter with 5th magnitude and a bit larger in our telescopes. Uranus is highest at 2:30 AM and remains up the rest of the night. Finder charts from astronomy magazines and websites assist the observer.
At nightfall, the Milky Way streams overhead from North to South. Many of the most famous constellations are found along this river of stars: Cassiopeia, Cygnus, Aquila, Sagittarius, also lesser known Delphinus and Scutum. Scutum is located halfway between Aquila and Sagittarius. A bright condensation can be spotted under dark, rural skies. This is the “Wild Duck” cluster. Admiral Smyth gave it that nickname when he observed it and said it resembled “a flight of wild ducks.” Binoculars show it as a bright knot of stars; telescopes reveal a myriad of stars. Reference books say it contains 2900 stars and is fifteen light years in diameter. This cluster, the eleventh on Messier’s list, is quite close, about 5500 light years away. However, it shines with the brilliance of 10,000 suns.