Skywatch Line for Wednesday and Thursday, July 16 and 17, 2025, written by Alan French
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, July 16 and 17, 2025, written by Alan French.
The Sun rises at 5:32 A.M. on Wednesday and sets at 8:31 P.M. On Thursday it rises at 5:32 A.M. and sets at 8:30 P.M. Thursday lost just over 10 minutes of daylight compared to last Thursday.
The Moon was full last Thursday and is heading toward last quarter. On Thursday at 4:30 A.M. a 69% sunlit Moon will be 48 ½ degrees above the southeastern horizon Moonset will be at 1:07 P.M. and will rise again at 11:58 P.M, in the east northeast. It will be 48% in sunlight, having reached last quarter at 8:38 P.M. After last quarter, the Moon is moving toward new.
We see satellites because they are up in sunlight while we are down in the Earth’s shadow and darkness. Soon after sunset, during evening twilight, satellites stay in sunlight as they cross the sky and remain visible for the entire pass. Later, part of the Earth’s shadow lies overhead, and a satellite may enter or leave the shadow and disappear or appear when it is high in the sky. This can also happen when a satellite crosses overhead well before sunrise and morning twilight.
A late Thursday pass of the ISS (international Space Station), the largest and brightest satellite in our night sky, disappears into our Earth’s shadow as it is moving higher into the sky.
If you do not want to stay up until close to midnight, there is a pass that is lower in the sky, but earlier and crosses most of the sky. For this earlier pass, look for the ISS low in the northwest at 10:10 P.M. This pass will take the space station low across the northern sky, reaching a maximum altitude of 20 degrees and a maximum magnitude of -1.2.
The ISS will be moving toward the north, almost 20 degrees high, at 10:12. Just before 12:13 it will pass just below the familiar “W” pattern of Cassiopeia low in the north northeast and will then toward down toward the east northeastern horizon.
Later Thursday, look for the ISS coming up from the west northwestern horizon just before 11:46 P.M., below the Big Dipper’s bowl. By 11:48 it will just below the bowl and headed right toward it. From Schenectady, it will pass almost through the center of the bowl beginning at 11:48:22 (HH:MM:SS). It will reach a maximum magnitude of -2.4.
After the ISS emerges from the top of the bowl it will pass through the tail of Draco, the Dragon, seconds after 11: 49, and will immediately move into the Earth’s shadow and fade from view.