Night sky in December Highlights

Wednesday     11th  Dec          Venus and Saturn appear only 2º apart just after Sunset

Saturday          14th  Dec          Geminid meteor shower.

Sunday            22nd Dec          December Solstice (shortest day)

Monday           23rd Dec          Ursid meteor shower peaks.

Thursday         26th Dec           Annular Solar eclipse. Not visible from Europe

Sunday            29th Dec           Comet 2017 T2 closest approach to Earth (will be brighter in May)

Below is a chart showing the night sky on the 1st December around 10 pm. On the 11th of December (and a day either side), around 6:20pm low down in the SW sky you may see Venus and Saturn just 2º separating them. At that time, they will only be 13º above the horizon, the brighter Venus will be visible slightly earlier, with Saturn slightly above and to its right.

Moon Phases

Dec        4                    First quarter

Dec      12                    Full Moon

Dec      19                    Last quarter

Dec      26                    New Moon

Planets  (all times are Local Spanish time)

Mercury:-       Mercury starts December as an early morning object reaching an elevation of 12º above the SE horizon just before dawn breaks (around 7:30 am). But each day it is moving closer to towards the Sun, and becomes too close to be properly observed by the end of the year.

Venus:-           Is now an evening object and moving further away from the Sun. At the beginning of the month it can be seen about 12º above the SW horizon just after sunset (around 6 pm), by the end of December it will have moved to 21º above the SW horizon at sunset, while Venus itself sets nearer 8:30pm.

 Mars:-            Is visible in the early morning, rising 2 and a half hours before the Sun at the start of December, by the end of the month Mars will rise around 5am, reaching a position of 21º above the SE horizon by the time dawn breaks.

Jupiter:-         Jupiter may be briefly visible very low down in the SW immediately after sunset at the start of December, but passes behind the Sun on the 27th .

 Saturn:-          Saturn is following Jupiter,  appearing about 19º above the SW horizon after sunset at the beginning of December, but moving ever closer towards the Sun which it will pass behind in early January.

Uranus:-         Uranus becomes visible in the SE sky after Sunset, before it reaches an elevation of 63º as it crosses our meridian (10:20 pm start of month, 8:20 pm by the end of December), then setting in the early hours of the morning.

 Neptune:-       Neptune is still visible in the evening sky, but by the end of December it will set around 11:15 pm.

 Comet

The brightest comet visible is C/2017 T2 (PanSTARRS), currently magnitude 9-10, but well placed high up in our skies in the late evening. It starts the month near the bright star Capella, and over the month gradually moves halfway towards the constellation Cassiopeia (see chart below, the red line is the comet path) .

This comet will be getting brighter over the coming months. It is estimated that it will reach magnitude 7 in May, just below naked-eye visibility but well within the range for anyone with binoculars. While it “should” be at it’s brightest in May, its closest approach to Earth occurs this month on the 29th December when it will be 1.5 AU (227 million Km) from Earth.

Meteor Showers

The Geminid meteor shower is the main one this month. Meteors occur from the 4th to 17th of December, but its peak is expected to be the 14th of December. Predictions suggest best time late evening of the 14th or early hours of the 15th with a rate of just over a 100 meteors an hour as viewed from here, but there will be significant interference from Moon light being just 4 days after the full moon.

The Ursid meteor shower with its radiant in Ursa Minor is active from the 17th to the 26th, but peaks around 5 am on the 23rd December, which fortunately is close to a new Moon, predicted rate then is 7 meteors an hour.

Puppid-Velid meteor shower is expected to peak on the evening of the 7th, but as the radiant is still below the horizon then, not rising until after midnight, add to this a large Moon, and realistically you’re only likely to see 1 an hour before dawn on December the 8th.