The name for December is derived from the Latin “Decem” meaning “ten”. It was the tenth and last month in the Roman calendar.
- Closest to Earth: November 2 (228,589 miles super-size moon)
- Full Moon: December 6 (Cold Moon)
- Farthest from Earth: December 12 (251,395 miles mini-size moon)
- Last Quarter Moon: December 14
- New Moon: December 21
- Closest to Earth: December 24 (226,675 miles super-size moon)
- First Quarter Moon: December 28
- Mars will be low in southwest (Mars will appear in about the same position all month as it did last month). Watch the background stars pass by.
Morning before sunrise:
- Jupiter, look west all month
- Saturn rises with the Sun at the beginning of the month and is well placed low on the eastern horizon the last two weeks of the month
- Mercury and Venus spend most of the month behind the Sun. Both will be somewhat difficult to see this month. For Venus look west very low on the horizon just after sunset starting around Christmas Eve. Start looking for Mercury five days later. It will be below Venus and a challenge to see. Next month the two will be putting on a show.
- December 1: Sunrise 7:00am MST, Sunset 5:35pm MST
- December 18: Sun enters the astronomical constellation Sagittarius.
- December 21: The Sun enters the astrological sign Capricorn.
- December 31: Sunrise 7:20am MST, Sunset 4:44pm MST
- December 8: Earliest Sunset 4:34pm MST (by just a few seconds). Sunset times are the same (nearest minute) from December 6 to December 11.
- December 19: Satrunalia, an ancient Roman festival believed to be related to the date we celebrate Christmas
- December 21: Winter Solstice occurs at 4:03pm MST
- December 25: Equation of time is zero. (Sundials need no adjustment to account for the variations in the Earth’s orbital speed)
- December 13-15 late evening: Geminid meteors peak. Best observe before moonrise (13/14 11:39pm MST, 14/15 12:35am MST. Meteors will be radiating from the east.
- December 5 evening: A near full moon will be very close to Aldebaran, the brightest star in Taurus the bull. Look east after sunset.
- December 11 late evening: Moon will be below a bright Jupiter. Both are in the constellation Leo the lion. The star below left of the Moon is Regulus, the brightest star in Leo. Look east after 10pm MST.
- December 19 morning: A crescent moon will be above Saturn. Both are in the constellation Libra the scales. Look east around 6:15am MST (sunrise 7:15am MST).
- December 24-25: the Moon is next to Mars on December 24, and below the Moon on December 25 low in the west southwest horizon after sunset. Note Look before 7:00pm. Mars sets around 8:00pm.
- December 27: Chamberlin Observatory open house weather permitting. The observatory’s 20” telescope and telescopes belonging to members of the Denver Astronomical Society will be available for viewing. Click here for more information. Bring that new Christmas telescope if you need some help. There will be a lecture on how to use your new telescope starting a 7pm.
- December 15, 1970: The Soviet lander Venera 7 lands on Venus, the first lander to make a soft landing on another planet. The lander measured a surface temperature of 869 °F and an atmospheric pressure of 90 atmospheres. That’s equal to the pressure at a depth of 3050 feet in the ocean, well below the crush depth of most submarines. The lander lasted 23 minutes before succumbing to the extreme temperature and pressure.
- December 25, 1968: Apollo 8 achieves first lunar orbit by a manned craft.
Wishing you clear skies