Skywatch Line for Wednesday and Thursday, November 20 and 21, 2024, written by Alan French
This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, November 20 and 21, 2024, written by Alan French.
The Sun rises at 6:54 A.M. on Wednesday and sets at 4:28 P.M. On Thursday it rises at 6:55 and sets at 4:27. This Thursday has 14 ¼ minutes less daylight than last Thursday.
The Moon was full last Friday and is moving toward last quarter. On Wednesday the Moon rises toward the northeast at 9:00 P.M. By 10:00 P.M. the Moon will be 9 degrees above the east northeastern horizon and appear 68% sunlit. Reddish Mars, at magnitude -0.3, will be to the upper right of the Moon and just under 4 degrees away. Be sure to see this pairing! The Moon will be due south and 69 degrees high at 4:44 A.M. Thursday morning, with Mars close to 6 ½ degrees to its right.
On Thursday evening the Moon will rise at 10:09 P.M. in the east northeast. By 11:00 P.M. it will be 8 degrees above the horizon and it visible face will be 58% in sunlight. The Moon will reach last quarter Friday night.
Cassiopeia is now high in the north at 8:00 P.M., its brightest stars appearing like an upside down “W,” a pattern familiar to many. It is an area rich in stars and star clusters and fun to explore under dark skies with binoculars or a low power telescope providing a wide field of view.
While amateur astronomy is generally associated with telescopes, some celestial sights are best seen at low powers and wide fields of view, the realm of binoculars and “Rich field telescopes.” A good comet is a fine example.
The recent evening comet, Comet Tsuchinshan-ATLAS is a good example. At its best, it spanned too much sky for the restricted field of view offered by most astronomical telescopes. I had some of my best views with a pair of 8×32 binoculars offering an 8-degree field of view, and the comet’s tail almost spanned their view.
Most amateur astronomers include binoculars in their observing equipment. In the past, a 7 power binocular with a 50mm diameter lens, or 7×50 binocular, was the standard. They even came to be called “Night Glasses.” In recent years, a 10×50 pair is often recommended, giving up a little field of view for a little more reach. Increasing either aperture or magnification brings more celestial sights into view.
The easiest approach to binocular astronomy is one providing a low power, wide field of view, like the common 10×50 or 8×40. They are also useful for birding, nature study, and sports, so can be enjoyed for other pursuits and by other family members.
Serious binocular sky watchers often move onto larger and higher power binoculars, giving up portability by adding the need for some type of mount. In between the two worlds are Image Stabilized (IS) binoculars, which allow hand-holding somewhat larger and higher power glasses. Larger IS binoculars tend to be heavier than most standard binoculars, but provide steady hand-held views.