Skywatch Line for Friday, September 29, through Sunday, October 1, 2023

This is Dudley Observatory’s Skywatch Line for Friday, September 29, through Sunday, October 1, written by Sam Salem.

On Friday, Sun rises at 6:50am and sets at 6:40pm; Moon sets at 6:53am and rises at 6:58pm.

Full Moon occurs at 5:58am Friday morning. This is a “supermoon,” slightly closer and larger than the average full Moon, because the Moon is near perigee.

The full Moon closest to the equinox is also called the Harvest Moon. It’s the last of 4 full supermoons in a row this year. Look for the full super Harvest Moon to be about halfway between the 2 planets, very bright Jupiter and golden Saturn. Golden Saturn will rise over an hour before the full Moon and travel ahead of it in the sky through the night. Bright Jupiter will rise about 90 minutes after the Moon.

In early evening, look above the bright Moon to see if you can make out the Great Square of Pegasus through the moonlight. It’s balancing on one corner, making it the Great Diamond of Pegasus. The line from its top corner through its bottom corner points down at the Moon.

Mercury stands out nicely now low in the east in early dawn. Look for it far to the lower left of bright Venus. They’re about 2½ or 3 fists at arm’s length apart. Mercury is brightening, from magnitude –0.5 last Sunday morning to a magnitude –1.0 this Sunday.

Venus, at magnitude –4.7 in dim constellation of Cancer, is now about as high as its going to get as the “Morning Star.” Look east before and during dawn. It rises more than two hours before dawn’s first light. It sits far under Castor and Pollux. In a telescope Venus is a thick crescent: 1/3 sunlit.

Jupiter, at magnitude –2.8, rises in the east-northeast around the end of twilight. Watch for it to come up under the brightest stars of Aries. Jupiter dominates the eastern sky through late evening and shines highest in the south during the early-morning hours.

Saturn, at magnitude +0.6 in dim constellation of Aquarius, is the brightest “star” in the southeast in twilight. It’s three weeks past opposition. Saturn shines at a good height for telescopic observing by about 9pm. Fomalhaut twinkles two fists at arm’s length below it. Saturn stands highest in the south around 11pm.

Arcturus shines in the west as twilight fades away. Capella, equally bright, is barely rising in the north-northeast. They’re both magnitude 0. Later in the evening, Arcturus and Capella shine at the same height. When it does, turn around and look low in the south-southeast, far lower right of the bright Moon. There will be 1st-magnitude Fomalhaut at about the same height too. That bright light more than a third of the way from Capella to Fomalhaut is Jupiter. Higher above Fomalhaut is Saturn, glowing steadily with a pale yellowish tint.