Ah, the winter night sky, how we love thee. The shorter daytime means even longer to stargaze; if we are lucky here in Armagh we will get some high pressure days leading to crisp, clear, starry nights. So, in the evenings after your Christmas shopping has finished for the day why not give stargazing a go? And it’s not just stars you can look for this time of year!
If you decide to gaze into the winter night sky this December, please remember to give your eyes around 20 minutes to fully adapt to the dark sky – initially you may not be able to see a lot, especially if you live in a town or city. I would recommend checking out this light pollution map to see how light polluted where you live is; there might be a dark site a short drive from you!
There are also specific dates this month that would be better for stargazing due to the effect the moon has – a full, bright moon makes stars and galaxies harder to see, so bear that in mind. The chart below from Go Stargazing outlines the influence the moon will have.
The Cold Moon
The full moon in December will be on the 12th; this is called The Cold Moon. Aptly named, as December is set to be notably Baltic this year (excuse me the Northern Irish colloquialism, if you will). This was not always its name, as it is also known as the Moon before Yule; Yule being the ancient celebration around the Winter Solstice.
The Winter Solstice (21st December) marks the “shortest” day of the year as North Pole has its maximum tilt away from the sun, meaning the fewest hours of daylight. The Winter Solstice has held significance across humanity for millennia dating back to Neolithic cultures; astronomical events were used to plan harvesting crops, mating animals and other tasks. The Winter Solstice marked the “death and rebirth” of the sun and was celebrated by eating and drinking copious amounts with friends and family. In Northern Europe, Pagans celebrated this time of year and called it “Yule”.
The Milky Way
On the less moonlit nights of the month – why not spend a while outside and let your eyes adjust enough to witness our amazing Milky Way! The cold, crisp, long nights of December make it a great time to pay a little more attention to our little corner of the Universe; our home galaxy.
Depending on where you are based, you will need to allow time for your eyes to adjust to the dark (usually 20 minutes). But it will be worth the wait – you will see a milky band running across our night sky. This is our galaxy, side on, from the inside! Our galaxy is home to between 200 and 400 billion stars, and at least 100 billion planets. The space between the stars is filled with gas and dust, which gives it its milky appearance. At the centre, we are confident there lurks a supermassive black hole 4 million times the mass of the sun – but don’t worry! It’s 26,000 light-years from our little, itty bitty solar system.
There are a few opportunities in December to do some planet spotting; namely with Saturn and Venus.
Saturn is low on the horizon this time of year – visible southwest on the horizon at an elevation of 13 degrees (lookout for the teapot of Sagittarius to point you in the right area). With a small telescope or binoculars you’ll be able to observe not only Saturn’s rings, but its brightest moon; Titan. In case you missed the news earlier this year – Saturn now has 82 moons! But most of them are not observable from Earth.
Also of note: in the earlier portion of the month of December you’ll be able to catch a glimpse of Venus below Saturn (just after sunset).
The Geminid Meteor Shower
On the nights of December 14th & 15th (if nice and clear) we will have the opportunity to observe the Geminid Meteor Shower. The moon will be in its first quarter and so will not interfere with its light meaning we can really appreciate this shower. Just after 11pm, the Geminid Meteor Shower will be high in the sky in the south. Look out for potential bright flashes and near-fireballs! The meteors you can observe come from asteroid 3200 Phaethon – well worth a look out if clear.
I hope this guide has inspired you to give stargazing a go this December. It’s definitely a colder time of year to get into stargazing, so remember to wrap up warm! If any of you are lucky enough to get a telescope for Christmas, remember to look out for Saturn’s rings! And stay tuned for our January Night Sky piece – there’s plenty more universe to see from our humble corner of the cosmos.