Skywatch Line for Wednesday, November 21st, and Thursday, November 22nd, 2018

This is the Dudley Observatory Skywatch Line for Wednesday, November 21st, and Thursday, November 22nd, written by Louis Suarato.

The 98% illuminated, waxing gibbous Moon rises at 3:55 p.m. Wednesday. The Moon reaches its Full phase at 12:39 a.m. Friday. Look for the nearly Full Moon to rise on Thanksgiving evening at 4:26, 5 minutes after sunset. Thursday night, use binoculars to combat the glow of the Moon and find the Pleiades star cluster 15 degrees to its upper left. The star to the Moon’s lower left is Aldebaran, Taurus’ brightest. Aldebaran is an orange giant star located 65 light-years away. Aldebaran translates to “the follower” because it rises, and follows the Pleiades across the sky. Aldebaran, also known as Alpha Tauri, is the 14th brightest star in the sky, ranging from 0.75 and 0.95 magnitude. In 1782, William Herschel discovered Aldebaran’s faint companion. In 1888, S.W. Burnham discovered a 14thmagnitude double star to Herschel’s companion. Aldebaran has exhausted its hydrogen core, and its new helium core has expanded its hydrogen shell to 44 times the diameter of our Sun.

Mars continues to shine brightly in the constellation Aquarius, and can be found about 23 degrees over the southwest horizon at 9 o’clock. This week, NASA will announce the landing site for the Mars 2020 rover, which is scheduled to land on the planet in 2021. Among its other scientific goals, this mission will look for the existence of evidence of ancient life on Mars. Venus rises in Virgo at 4:04 a.m., just 3 degrees to the left of Virgo’s brightest star, Spica.

You’ve most likely noticed how bright the Full or gibbous Moon may look when viewing it through a telescope. You may want to consider obtaining a moon filter for observing under these conditions. A moon filter is similar to sunglasses in that it reduces glare. When placed between the diagonal and the eyepiece, the filter dims the brightness, and displays details more clearly. Moon filters can be fixed or variable. A fixed moon filter allows a fixed percentage of light through the eyepiece. A variable filter allows you to choose the percentage. Moon filters can be threaded between the diagonal and your eyepiece, and are made to fit either 1 ¼ inch or 2 inch diameters.

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