This is the Dudley Observatory Skywatch Line for Wednesday, December 5th, and Thursday, December 6th, written by Louis Suarato.
The 2% illuminated, waning crescent Moon sets at 3:47 p.m. Wednesday. Arise early to see the crescent Moon 5 degrees above Mercury. Look low above the south-southeastern horizon after 6:15 a.m. for the Moon and Mercury. The Moon will reach its New phase at 2:21 a.m., Friday. Look higher above the Moon for Venus, now 30% illuminated, and shining at magnitude -4.85. Later this month, Jupiter will be joining the two innermost planets in the pre-dawn sky. Mars and Saturn are the only two easily visible evening planets. Saturn will set at 6:03 p.m., and Mars will set 11:26 Wednesday night.
Take advantage of these moonless nights to observe three binocular to small telescope-viewable comets. Comet 38P/Stephan-Oterma will remain at magnitude 9-10 until January. Wednesday night, after 10 p.m., Comet 98P/Stephan-Oterma will be above the eastern horizon. Look approximately 8 degrees below, and left of the brightest head of Gemini, Pollux, for this comet. The second observable comet is 11.9 magnitude 69P/Taylor. The best time to observe this comet is between 7 p.m., and 2 a.m.. At 10 p.m., Comet 69P/Taylor will be about 40 degrees above the southern horizon, and 30 degrees to the right of Rigel in the constellation Orion. The brightest of the three comets, 46P/Wirtanen, can be found 8 degrees to the right of Comet 69P/Taylor. Comet 46P/Wirtanen will make its closest approach to Earth in over 400 years when it travels to within 7.2 million miles on December 16. That will be among the 10 closest comet approaches since 1950, and in the top 20 approaches since the 9th century. While some predict Comet 46P/Wirtanen to reach 3rd magnitude, others have noted its small size make cutail its brightness and may even its ability to form a tail.