This is the Dudley Observatory Skywatch Line for Wednesday, December 26th, and Thursday, December 27th, written by Louis Suarato.
The 80% illuminated, waning gibbous Moon sets at 10:30 Wednesday morning. The Moon rises again at 9:10 p.m. in the constellation Leo. The bright star to the upper right of the Moon is Regulus, Leo’s brightest. Look for Mars, the night’s only easily visible planet, about 45 degrees above the southern horizon after sunset. The morning sky features three planets. The brightest is Venus, which rises at 3:32 am. Jupiter rises next at 5:33, followed by Mercury, 25 minutes later. Look over the southeast horizon before sunrise to see all three planets.
The asterism known as The Winter Circle, or Winter Hexagon, is comprised of the stars Rigel, Aldebaran, Capella, Pollux, Procyon, and Sirius. Rigel is the brightest star in the constellation Orion, and the seventh brightest star in the sky, occasionally being outshone by Betelgeuse. It is estimated to be between 79 and 115 times the Sun’s radius. Rigel is 863 light-years away, and shines at magnitude 0.15. Aldebaran is the brightest star in Taurus, and the fourteenth brightest star in the sky. It is 65 light-years from the Sun, about 44 times as large, and shines at magnitude 0.85. Capella is Auriga’s brightest star, and the sixth brightest overall. It is 42.9 light-years away, and this quadruple star system’s two yellow giant stars are 2.5 times as massive as our Sun. Capella shines at magnitude 0.05. Pollux is the brightest of the stars in Gemini and, at the distance of 34 light-years, is the closest giant star to the Sun. Pollux is about nine times the size of the Sun, and shines at magnitude 1.15. Procyon in Canis Minor, is the eighth brightest star in the sky, shining at magnitude 0.40. This star is the eight brightest in the sky, and is 11.46 light-years away, making it one of Earth’s closest stellar neighbors. Sirius is Canis Major’s brightest, and at magnitude -1.45, the brightest in our sky. This binary system is 8.6 light-years away, and contains two of the eight nearest stars to the Sun.