Skywatch Line for Wednesday and Thursday, October 23 and 24, 2024, written by Alan French

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, October 23 and 24, 2024, written by Alan French.

The Sun rises at 7:19 A.M. on Wednesday and sets at 5:59 P.M. On Thursday it rises at 7:20 and sets at 5:58. This Thursday has 19 minutes, 12 seconds less daylight than last Thursday.

The Moon was full last Thursday and is now headed toward third quarter, so the waning Moon rises late in the evening. On Wednesday a 52% sunlight Moon will rise in the northeast at 11:09 P.M. Early Thursday morning the Moon will reach last quarter. On Thursday, the Moon will not rise until 18 minutes after midnight on Friday morning, when its visible face will appear 41% in sunlight.

During full daylight, the Moon appears quite washed out and dull against the bright blue sky, but the Moon can hold its own for a spell just after sunrise, looking bright and quite lovely against the blue sky. On Wednesday morning look for the Moon, appearing slightly gibbous, high in the southwest at 7:30 A.M. At 7:30 A.M. Thursday it will be more toward the south southwest and less than half sunlit.

Wednesday’s Moon will set at 2:21 P.M in the northwest and Thursday’s Moon will set at 2:55 P.M. toward the northwest.

Comet Tsuchinshan-ATLAS has been fading as it moves away from the Sun, but remains a nice sight through binoculars. It has also moved higher into our sky, stays visible longer, and is unfettered by a bright Moon. The comet now sets soon after 10 P.M., before moonrise.

At 7:30 P.M. on Wednesday the comet will be 28 degrees above the west southwestern horizon. By Thursday it will be almost a degree higher. It should still be easy to sweep up in binoculars, but it will continue to fade as it moves farther away from the Sun.

NASA launched its Advanced Composite Solar Sail System (ACS3) back in April. It is designed to test solar sail technology and help develop larger spacecraft that use this propulsion system. It orbits about 1,000 kilometers (600 miles) above our Earth and its 80-square-meter sail reflects enough sunlight so it can appear as bright as the brightest stars in the Big Dipper.

We have a good chance to see the ACS3 solar sail on Thursday night. At 8:16:15 (HH:MM:SS) it will emerge from the Earth’s shadow and appear 8 degrees north of Alpheratz (Alpha Andromeda), the 2nd magnitude star that is one of the two similarly bright stars in Andromeda and marks the northeastern corner of the Great Square of Pegasus. When it emerges into sunlight and our view, the ACS3 will be moving northward.

You can also look south of the familiar “W” outlining Cassieopia for a satellite moving toward the constellation just after 8:16 P.M. Seconds after 8:17 the ACS3 satellite will be moving through Cassiopeia. At 8:18 the ACS3 will be passing east of Polaris, the North Star, and after 8:20 it will be passing east of the Big Dipper’s bowl, headed down toward the northern horizon.