Skywatch Line for Wednesday and Thursday, September 18 and 19, 2024, written by Alan French
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, September 18 and 19, 2024, written by Alan French.
The Sun rises at 6:39 A.M. on Wednesday and sets at 6:59 P.M. On Thursday it rises at 6:40 and sets at 6:57. This Thursday has 19 minutes, 06 seconds less daylight than last Thursday.
The Moon was full on Tuesday, having completed half its trip around our Earth since new, and is now moving toward last quarter.
On Wednesday the Moon rises at 7:22 P.M. in the east. By 9:00 P.M. the bright gibbous Moon, appearing 98.6% in sunlight and essentially full, will be 17 degrees above the east southeastern horizon. The Moon will be due south and 52 degrees high at 1:48 A.M. Thursday. It will set toward the west at 8:29 A.M.
On Thursday night moonrise is at 7:46 P.M. in the east northeast. By 9:00 P.M. the Moon will be 12 ½ degrees above the eastern horizon and its visible face will be 94% in sunlight. The terminator, the line between sunlight and darkness, is now the sunset line marching
relentlessly across the lunar surface as it moves toward new. The Moon will be due south and 59 ½ degrees high at 2:40 A.M. Friday. It will be 93% sunlit. The Moon sets at 9:51 A.M. Friday in the west northwest.
Saturn rises in the east at 6:38 P.M. on Wednesday and by 10 P.M. is 31 degrees high toward the southeast. It appears small at a magnification of 50 or 60 in an astronomical or spotting telescope, but its rings are visible. Saturn’s moon Titan, at magnitude, +8.6, is bright enough to see in any telescope.
On Wednesday night around 10 P.M. Titan is just to the west of and a bit lower than the west ring tip, about one Saturn diameter away from the planet. (Some astronomical telescope invert or reverse their images. A spotting scope gives an image with the same orientation your eye sees.) On Thursday night at 10 P.M. Titan will be a little over twice Saturn’s diameter to the west of the ring tip.
Planets are best through a telescope when due south and highest in our skies. On Wednesday night Saturn will be due south, or transit, at 12:10 A.M. Thursday morning, when it will be 39 degrees above the horizon. On Friday morning, Saturn will be due south and highest at 12:36 A.M. The hour around its transit time usually provides the best views through a telescope.
With Saturn almost 8 degrees south of the celestial equator it does not get very high in our skies. Each upcoming opposition of Saturn over the coming 8 years will find Saturn farther north, so the planet will move higher and our views will improve. Also, our atmosphere and viewing conditions do not always follow our generalizations, and persistence usually pays off. In addition to catching those steady nights, frequent planetary observing also improves your ability to spot fine and subtle details.