Skywatch Line for Wednesday and Thursday, January 17 and 18, 2024 written by Alan French
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, January 17 and 18, written by Alan French.
The Sun rises at 7:22 A.M. on Wednesday and sets at 4:49 P.M. On Thursday it rises at 7:22 and sets at 4:50. This Thursday has a little less than 11 ½ minutes more daylight than last Thursday.
The Moon was new last Thursday and reaches first quarter late Wednesday evening. This makes these two nights ideal for exploring the Moon with a telescope. Even a modest telescope will provide impressive views of the lunar landscape. Lacking a telescope, a steadily held or supported binocular will show a lot of detail on the Moon.
When the Moon is at first quarter the terminator, the line separating the sunlit portion from darkness, crosses the center of the Moon’s visible face and is the sunrise line. Here, the Sun is low in the lunar sky, shadows are long, and detail stands out in bold relief. As the sunrise line marches eastward across the Moon’s face more details come into view, and the lighting of previously seen details, now seeing a higher Sun and casting shorter shadows, changes, altering their appearance.
On Wednesday night the Moon is due south and highest at 5:39 P.M. With the Moon both at first quarter and 59 ½ degrees above the horizon, it is an ideal time to turn a telescope or binoculars toward the Moon. The view will only improve as the remaining traces of evening twilight disappear. Note bright Jupiter 12 degrees to the east of the Moon.
The Moon rises later Thursday and will not be south until 6:27 P.M., when it will be 62 ½ degrees high and 59% in sunlight, another excellent observing window. Jupiter will be just over 3 degrees below and a bit west of the Moon. The pair will make a pretty sight.
Both nights feature nice evening passes of the International Space Station (ISS) over the Schenectady Area. The pass Wednesday night will be higher and under darker skies.
On Wednesday night the ISS passes almost directly overhead. When high in the sky it will reach magnitude -3.8, making it easy to spot. Look for the space station coming up from the southwestern horizon at 6:14 P.M. It will pass just north of Saturn and then begin moving through the Great Square of Pegasus just before 6:16. It will travel along Andromeda, be essentially overhead moving north-eastward just before 6:17, and be passing through the northern part of Perseus, southeast of Cassiopeia, at 6:17. The ISS will enter the Earth’s shadow and begin fading from view seconds before 6:18, when 38 degrees above the northeastern horizon.
Thursday’s appearance of the ISS will be earlier, the sky will be bright with evening twilight, and it will travel lower across the sky, but the space station will pass near the Moon and Jupiter.
On Thursday look for the ISS in the southwest at 5:26 P.M. At 5:28 the space station will be in the south and headed toward bright Jupiter and will pass just below the planet at 5:28:42 (HH:MM:SS) and will be in the southeast at 5:29. Its path will take it across the eastern sky and down toward the east northeastern horizon.