This is the Dudley Observatory Skywatch Line for Monday and Tuesday, October 26th, and 27th, written by Joe Slomka.
The Sun sets at 5:55 PM; night falls at 7:30. Dawn begins at 5:49 AM and ends with the Sun rising at 7:24.
The constellation Aquarius hosts the Moon on both nights. Monday’s 13-day-old Moon rises at 4:18 PM, 30 arc-minutes in size and appears 82% illuminated; it sets at 3:15 AM. Tuesday’s Moon is slightly smaller, but 88% lit, rises at 4:42 PM and sets at 4:16 AM, Wednesday.
Jupiter, Pluto and Saturn continue to occupy Sagittarius and illuminates the southwestern sky. Jupiter rises first at 1:30 PM, almost 21 arc-seconds in diameter, glimmers with minus 2nd magnitude, is highest at 6 PM and sets at 10:29 PM. Observers can witness the moon Europa begin to cross the planet’s face at 9:55 PM, Tuesday. Pluto can be telescopically found between Jupiter and Saturn, glowing with minus 14th magnitude, appear as a tiny dot which rises at 1:41 PM and sets at 10:38 PM.
Saturn rises at 1:49 PM, glimmers with zero magnitude and sized 16 arc-seconds; best seen at 6:23 PM it sets at 10:58 PM. Both Jupiter and Saturn are easy to find and explore. However, their stay is getting shorter daily and will soon be out of sight.
In Aquarius, Neptune rises at 4:12 PM, shines with 7th magnitude, spans 2 arc-seconds, best spotted at 9:50 PM and sets at 3:32 AM. Uranus, in Aries, rises at 6:05 PM, shines with 5th magnitude, 3 arc-seconds wide and best seen at 1 AM. Neptune reaches Opposition, when it is best observed, on October 31st. Uranus lies about 21° East of Mars.
Mars, in Pisces, still outshines Jupiter, with minus 2nd magnitude, but shrinks and dims daily, now that it has passed Opposition. Mars rises at 5:21 PM, highest at 11:38 PM and sets at 5:59 AM. Mars flies in formation with the Moon and Uranus on both nights. The Red Planet contains plenty of surface detail for seasoned amateurs and first timers.
Minor Planet 1 Ceres, shining with 8th magnitude and 97% lit, accompanies Neptune in Aquarius. It rises at 4:28 PM, highest at 8:55 PM and sets at 1:23 AM.
Venus is the last to rise, in Virgo, at 4:20 AM. By 5 AM, it blazes with minus 4th magnitude, 13 arc-seconds wide and is 80% lit.
Sky charts for Pluto, Uranus, Neptune and 1Ceres can be obtained from astronomy magazines and websites.
The variable star Algol, in Perseus, is high in the northeastern sky by 8 PM. It is at minimum at 8:18 PM on Monday and should be followed 2 hours before and after minimum. Algol, the “Demon Star,” varies its light every 2 days, 20 hours and 49 minutes. It fades from second magnitude to third – easily seen by the naked eye. Two hundred thirty-two years Monday, John Goodricke theorized that a dimmer star was partially eclipsing a brighter star. In 1889, the new technique of spectroscopy verified this theory. The main star is one hundred times the Sun’s luminosity. The eclipsing star is actually slightly brighter than our Sun. There is a third star that orbits the system once every 1.8 years, but plays little part in the occultation. The system is about 100 light years away and the most easily studied “eclipsing binary.” Astronomy magazines and websites provide timetables of its eclipses.