Skywatch Line for Wednesday and Thursday, June 25 and 26, 2025, written by Alan French

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, June 25 and 26, 2025, written by Alan French.

The Sun rises at 5:18 A.M. on Wednesday and sets at 8:38 P.M. On Thursday it rises at 5:19 A.M. and sets at 8:38 P.M. Now that we are past the summer solstice the Sun is moving south and we are losing daylight. Thursday lost one minute of daylight compared to last Thursday.

The Moon reached last quarter this past Wednesday and will be new late this Wednesday morning. This new Moon begins lunation 1268. As we have mentioned, the system for numbering lunations is arbitrary and began with the new Moon on January 17, 1923, using a series described by Ernest W. Brown.

A half hour after sunset, 9:08 P.M. on Wednesday, a slender young Moon will be just under 3-degrees above the northwestern horizon. It will be tough to spot the slim, 0.6% illuminated, crescent. You will need an excellent view to the northwest and clear skies, free of clouds and haze. If conditions are not perfect, or if the young Moon eludes you, binoculars may aid the hunt.

Thursday night’s crescent Moon will be easier to spot. At 9:08 P.M. the 3.4% sunlit crescent will be 10 degrees above the west northwestern horizon. As a bonus +0.1 magnitude Mercury will be just over 4 degrees to the north (left) of the Moon. Depending on evening twilight and transparency, binoculars can help spotting Mercury. The Moon will set at 10:16 P.

As the Moon moves toward first quarter in the coming days it will move higher into the evening sky each night, but it will be low toward the south. The Moon will reach first quarter early on the evening of Wednesday, July 2.

The International Space Station (ISS) is now in the morning sky. If you inclined to stay up until well after midnight on Thursday or get up early on Friday, there is a fine pass soon after 3 A.M. Friday, it will
be overhead, bright, and the space station will move out of the Earth’s shadow and into view when high in the sky.

The ISS will move out of the Earth’s shadow at 3:09:48 A.M. (HH:MM:SS) when 51 degrees above the southwestern horizon. If you imagine a line joining Altair and Vega, the ISS will appear about 13 degrees to the west southwest of the midpoint of that line. (A fist held at arm’s length spans 10 degrees across the knuckles.) It will quickly brighten to magnitude -3.7 so should be easy to spot if you are looking in the
right area. The path of the ISS will take it overhead and it will move through Cygnus, the Swan, reaching magnitude -3.9. It will be highest at 3:10:33.

After 3:11 it will be passing north of Cassiopeia and then will pass through Andromeda and Perseus as it heads toward the northeastern horizon. It will probably be too low to spot around 3:14 but will not
set until 3:16.