This is the Dudley Observatory Skywatch Line for Monday and Tuesday, September 28th and 29th written by Joe Slomka.
The Sun sets at 6:42 PM; night falls at 8:16. Dawn beaks at 5:15 AM and ends with sunrise at 6:50.
The darkening sky reveals only one bright planet – Saturn. Saturn appears moderately low in the southwestern sky. It appears between Libra and the head of Scorpius and is slowly closing in on the Scorpion. Saturn sets at 9:21 PM.
Nightfall reveals Neptune still keeping station in Aquarius. Finder charts, found in astronomy magazines, websites and apps, assist in locating this distant world. Neptune sets at 4:30 AM.
Normally visible Uranus, in Pisces, may not be observable on Monday and Tuesday evenings. The Moon, which experienced an eclipse last night, has parked itself less than two degrees from Uranus. The overwhelming lunar brilliance will probably drown Uranus by its light and make observation of the planet difficult. The sixteen-day-old Moon rose after 7 PM on both nights and sets during daylight, appearing nearly full on both evenings.
Astronomical Dawn introduces three new characters on stage, in Leo. Brilliant Venus rose at 3:18 AM, second in brightness only to the Moon. In high-powered binoculars or telescopes, Venus appears about one-third illuminated and keeps shrinking in size. First magnitude Mars is next to rise, at 3:57 AM; it lies about eleven degrees from Venus, but only three degrees from Leo’s brightest star, Regulus. Its rusty color distinguishes it from the white star Regulus. Jupiter is the last to rise, at 4:38 AM. It is quite low on the eastern horizon, about seven-an-a-half degrees to Mars’s lower left. All three remain up well into daytime and, in the coming months, will populate the pre-sunrise sky.
Since Autumn began last week, let us consider the Fall constellations. Some “Summer Constellations” are misnamed. They rise in early summer, but are best seen in late summer or early fall. Between nightfall and midnight, the Andromeda saga is displayed. Her parents are Cepheus and Cassiopeia. Cepheus is house-shaped and points to the North Star. Cassiopeia looks like a “W” or “M”. Andromeda is depicted by a chain of stars that flow from the upper left of the Great Square of Pegasus, the horse. Perseus is a constellation below Cassiopeia with a long and a short leg. Cetus, the sea monster, swims low on the horizon. These constellations together account for twelve percent of the celestial sphere. Also visible are Lacerta, the lizard and Triangulum, the Triangle. All are in excellent position to be seen tonight.