This is Dudley Observatory’s Skywatch Line for Friday, December 18, through Sunday, December 20, written by Alan French.
Reaching first quarter early Friday, a waxing gibbous Moon will dominate the early evening sky this weekend. The Moon will be due south and highest – ideally placed for observing with a telescope or binoculars – at 6:11 pm Friday, 7:03 pm Saturday, and 7:56 pm Sunday.
There is a bright and interesting pass of the International Space Station (ISS) over the Capital District on Saturday night. When halfway across the sky and well above the northern horizon, the station will move into our Earth’s shadow and fade from view. (Times will be given in hours, minutes, and seconds.)
Look for the ISS coming up from the northwestern horizon at 6:08:36 pm. Its path will take it up toward the North Star, Polaris, and just after it passes above Polaris it will move into the Earth’s shadow and disappear. This happens at 6:11:27 pm.
There is another pass of the ISS across the northern sky on Sunday night. This pass will be lower and will not move into the Earth’s shadow until it is approaching the eastern horizon.
Look for the space station at 5:15:38 pm when it will be moving up from the northwestern horizon. It will be highest at 5:18:39 when it will be thirty-two degrees above the north northeastern horizon, and will move into the Earth’s shadow and fade from view at 5:21 when just 14 degrees above the eastern horizon.
Its path will take it above the Big Dipper, which is low in the north and may be obscured by trees in many locations. In the northeastern sky the ISS will pass through the constellation Auriga, passing very closed to its brightest star, Capella. Soon after moving through Auriga it will fade from view.
When the prominent pattern of the Big Dipper, part of the constellation Ursa Major, the Great Bear, is low in the north, Cassiopeia, the Queen, rides high in the north. The Queen is easily spotted by her familiar “W’ of bright stars, although it will be tipped almost completely over and look like an “M.”
The area around Cassiopeia is rich in faint stars, many of which are revealed through binoculars.