This is the Dudley Observatory Skywatch Line for Monday and Tuesday, October 21st and 22nd, written by Joe Slomka.
The Sun sets at 6:04 PM; night falls at 7:38 PM. Dawn begins at 5:24 AM and ends with the Sun rising at 7:16.
Two elusive planets appear in our evening sky. Mercury and Venus lie close together in the West-Southwest constellation of Libra, just after Sunset. Venus is brightest with magnitude minus 3.8 and appears about 95% illuminated; however, it lies very close to the horizon. Mercury is a bit higher, shines with zero magnitude and appears about 61% lit. Both set by 6:55 PM. Both require an unobstructed horizon and binoculars to find them within the setting Sun’s glare.
Jupiter still occupies Ophiuchus, but is quite low. The giant planet shines with minus 1.8 magnitude, and appears about 34 arc-seconds in size. It continues an eastward movement, keeping itself in our skies as long as possible. It sets at 9:04 PM. Saturn, inhabiting Sagittarius, glows with zero magnitude and appears about half Jupiter’s size. The Ringed Planet, too, creeps eastward and sets at 10:50 PM.
Gas giant planets Uranus and Neptune are best viewed around 10 PM. Neptune rose first in Aquarius, appears about 2 arc-seconds in size and glimmers with 8th magnitude. Uranus trails Neptune by about 2 hours. It appears in Aries, brighter with 5th magnitude and a bit larger. Finder charts for both are available from astronomy magazines and websites. Neptune sets at 4:08 AM; Uranus sets during daylight.
The variable star Algol, in Perseus, becomes its dimmest at 11:04 PM on Tuesday night. Observers should begin watching about 2 hours before and after that time.
The Last Quarter Moon rises in Cancer at 12:12 AM on Tuesday, is highest at 7:49 AM and sets at 3:20 PM. Wednesday, the Moon appears a bit dimmer and thinner, rising in Leo at 1:24 AM, highest at 8:45 AM and sets at 4 PM. Thus, it is possible to observe the Moon during daylight, provided that a cloudless sky is available.
Pre-dawn observers on Monday and Tuesday nights may see meteors streaming from the area of Orion’s club. This is the annual Orionid meteor shower. Meteor showers result when Earth’s orbit crosses paths with debris from comets’ tails. The Orionids come from the most famous comet of them all – Comet Halley, which returns about every 76 years. Astronomers predict an average year for the Orionids. The shower’s peak is Tuesday afternoon. The constellation is high and the Moon rises after midnight. It is recommended that the sky watcher begin around 10 PM, before Moonrise. After Moonrise, the brilliant Moon may hinder observation of dimmer meteors. If observing conditions are good, one may see up to twenty meteors per hour. The observer needs no special equipment; he simply stares at the sky. Since this is Autumn, cold weather clothing and boots help avoid the chill.