Skywatch Line for Friday, October 27, through Sunday, October 29, 2023
This is Dudley Observatory’s Skywatch Line for Friday, October 27, through Sunday, October 29, written by Sam Salem.
On Friday, Sun rises at 7:23am and sets at 5:55pm; Moon sets at 5:45am and rises at 5:22pm.
On Saturday, full Moon occurs at 4:24pm. The Moon rises at sunset. As twilight deepens and the Moon climbs higher, there will be Jupiter shining just 3° below or lower left of it. Watch the Moon and Jupiter appear to draw closer together through the evening. Jupiter will pass 2° below the brilliant Moon in the early morning hours. They both appear in the same spot of the sky as Jupiter and the full Moon are both very close to opposition, in the opposite direction from the Sun as seen from Earth’s point of view.
This full Moon is called the Harvest Moon. Autumn full moons do have special characteristics related to the time of moonrise. All full moons rise around sunset. The moon rises about 50 minutes later each day, as it moves in orbit around Earth. But when a full Moon happens close to an autumn equinox, the Moon on the nights before and after the full Moon rises closer to the time of sunset. For mid-temperate latitudes, the Moon rises only about 20 to 25 minutes later daily for several days before and after the full Harvest Moon.
Venus, brilliant at magnitude –4.5 in the constellation of Leo, shines high in the east before and during dawn. It rises nearly 2½ hours before dawn’s first light on the eastern horizon. In a telescope Venus, is barely beginning to turn gibbous.
Jupiter, at magnitude –2.9 in the constellation of Aries, is nearly at its November 2nd opposition. It rises in twilight and dominates the east during the evening. It’s highest in the south around 1:00am. It sits low in the west at dawn. Jupiter is now at its brightest and telescopically largest 49 or 50 arcseconds wide.
Saturn, at magnitude +0.7 in the dim constellation of Aquarius, glows a steady pale yellowish in the southeast as twilight fades out. Fomalhaut twinkles nearly two fists at arm’s length below it. Saturn is high in fine telescopic viewing position through the evening.
It is nearly the end of October, but Deneb still shines near the zenith as the stars come out. Brighter Vega is still not far from the zenith, toward the west. The third star of the “Summer” Triangle, Altair, remains very high in the southwest. What we see is the result of sunset and darkness arriving earlier and earlier during autumn. Which means if you watch the stars soon after dark, you’re looking earlier and earlier by the clock. This counteracts the seasonal westward turning of the constellations.
Watch the “Demon Star” just in time for Halloween. Algol in Perseus should be at its minimum brightness late Sunday night, magnitude 3.4 instead of its usual 2.1, for about two hours centered on 1:23am. Algol takes several additional hours to fade and to re-brighten. The star Algol takes its name from an Arabic word meaning the Demon’s Head or, literally the Ghoul. It represents the terrifying snaky head of the Medusa
monster. The Demon Star is easy to find. The conspicuous W or M-shaped constellation Cassiopeia enables you to star-hop to Perseus. Look below Cassiopeia toward the horizon to spot the dangling spike shape of Perseus. Off to the right of the spike is Algol. At mid-northern latitudes, the Demon Star appears for at least part of the night all year round. But it’s best seen in the evening sky from autumn to spring. It’s visible in the northeast sky in autumn, shines high overhead in winter, then swings to the northwest sky by spring.