Skywatch Line for Friday, July 23, through Sunday, July 25, 2021

This is Dudley Observatory’s Skywatch Line for Friday, July 23, through Sunday, July 25, written by Sam Salem.

On Friday, Sun rises at 5:38am and sets at 8:25pm; Moon sets at 4:37am and rises at 8:39pm. The Moon will reach its full phase on Friday at 10:37pm. July full Moon is often called the Buck Moon, Hay Moon or Thunder Moon. That’s because at this time of year buck deer begin to grow velvety antlers and farmers load hay in their barns amid the summer season’s frequent thunder showers. The Moon is full when it is opposite the Sun in the sky. Therefore, full Moon rises in the east as the Sun is setting and sets in the west at sunrise.

On Friday, look for Saturn about a fist at arm’s length to Moon’s left. By dawn on Saturday, they shift to the southwest and twist around so that Saturn is above the Moon. In the east after dark Saturn shines upper right of the Moon, and Jupiter shines farther to the Moon’s left. By dawn this scene of action shifts to the southwest and the pattern rotates clockwise.

On Saturday, see both Regulus and Mars well down to Venus’s lower right, by 4° and 7° respectively. Venus, at magnitude –3.9, continues to shine low in the west during twilight. Lower left of it is tiny Mars, 200 times fainter at magnitude +1.8. Mars gets lower every day. Both planets set before twilight ends. Upper left of Venus you’ll find Regulus moving closer to Venus day by day. It’s brighter than Mars by a half magnitude.

Saturn, at magnitude +0.2 in constellation Capricornus, and Jupiter, at magnitude –2.8 in constellation Aquarius, rise in the east-southeast in twilight. Jupiter rises an hour after Saturn. Saturn sits 20° to Jupiter’s upper right. They’re highest in the south, at their telescopic best, around 2am. They’ll reach opposition next month, so they’re already about as close and big as they’ll get.

Uranus, at magnitude 5.8 in constellation Aries, is well placed in the east before dawn begins.

Neptune, at magnitude 7.8 in constellation Aquarius 22° east of Jupiter, is higher in the south-southeast before dawn begins.

As summer progresses, bright Arcturus moves down the western side of the evening sky. Its pale ginger-ale tint helps identify it. Off to Arcturus’s right in the northwest, the Big Dipper scoops to the right.

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