December 2020 Skies

December 2020 Skies

December Skies – Don’t miss out on the Geminid Meteor Shower and the Grand Conjunction of Jupiter and Saturn!

A Meteor Shower (when the Moon is not up)!  Three bright planets in the evening sky: Mars, Jupiter and Saturn, plus the brightest planet of them all in the morning sky: Venus. Best of all we have the opportunity to view Jupiter and Saturn will have their once-in-20-years conjunction on December 21 – but more on that later as this has not been as spectacular for several hundred years

The Moon this Month

Third quarter Moon: 11:36am December 8th  

New Moon: 3:16am December 15th         

First Quarter: 10:41am on December 22nd

Full Moon: 2:28 pm December 30th

Planets in December

December sees all five bright planets visible. All except for Mercury are starting to gradually dim as they slowly move further from us. Never fear, though, they are all still easily visible and not too hard to find. Jupiter, Saturn and Mars are in the evening sky while Mercury and Venus still grace the early mornings.

Mercury will be hard to see as it will be very low in the morning sky and you will need a good eastern horizon by the end of the month it will be visible low in the evening sky so wait until January to try to catch this elusive planet.

Venus will continue to dazzle us as the morning star throughout December and into 2021. It rises in southern latitudes about 1.5 hours before sunrise. December will see Venus due to its faster orbit around the Sun moving farther and farther away from Earth.

Mars can be seen high in the northern sky at nightfall and its orange red brightness will be visible throughout December until past midnight. In October 2020, Mars was brighter than it will be again until September 2035. Since on October 13, 2020, Mars reached opposition in our sky, being a mere 68 million km away from us. Opposition occurs when a planet is opposite the Sun as seen from Earth. At opposition, Earth was sweeping between Mars and the Sun. Now having a smaller, faster orbit – Earth is speeding along, leaving Mars behind meaning that unfortunately in the months ahead, Mars will slowly but surely dim in our night-time sky. It will remain bright throughout this month and will be close to the Moon around the nights of Dec 21 – Dec 23.

Jupiter and Saturn are getting closer, as they near their once-in-20-years conjunction on December 21, 2020. At their closest, they will be only 0.1 degrees apart. That I s just 1/5 of a full moon diameter. You will see them easily in a single binocular field all month and then as they get closer together in the same field. Start watching them now, and you’ll see them draw close together.

At 18:20 UTC on the Dec. 21, Jupiter and Saturn will appear closer together in Earth’s night sky than they have been since the Middle Ages, offering people the world over a night sky treat to ring in the summer solstice for us In the South and the winter solstice for our northern friends. Thus will be in the evening for our northern hemisphere mates but 5:20am AEDT on Dec 22 for us and the planets are not visible at that time.

However the picture from Stellarium below shows Jupiter and Saturn at 9:20pm AEDT on the night of the 21st for Eastern Australia. They will still appear very close. This is described as a great conjunction.

Generally speaking, a conjunction is when two objects appear close to each other in the sky.

A conjunction of Jupiter and Saturn—which only happens about once every 20 years—is called a great conjunction.

Alignments between these two planets are rather rare, occurring once every 20 years or so, when they pass in their orbits – Saturn takes 29.5 years to orbit the Sun while Jupiter takes just under 12. This conjunction is incredibly rare because of how close the planets will appear to one another in the sky.

December 16 gives us an evening photo opportunity when Jupiter, Saturn and the crescent Moon make close approach in the western evening sky.

If you miss this one you will need to wait around until March 15, 2080. The two planets won’t make such a close appearance again sometime after the year 2400.

This is how it should look in a decent size telescope where your field of view would normally be about the size of the Full Moon.

Geminid Meteor Shower

The Geminids are considered to be one of the most spectacular meteor shows of the year, with the possibility of seeing around 120 meteors per hour at its peak, which is on December 13 or 14, depending on your time zone.

This is the one major shower that provides good activity prior to midnight as the constellation of Gemini is well placed from midnight onward. The Geminids are often bright and intensely coloured. Due to their medium-slow velocity, persistent trains are not usually seen. These meteors are also seen in the southern hemisphere, but only during the middle of the night and at a reduced rate.

The shower owes its name to the constellation Gemini because the meteors seem to emerge from this constellation in the sky. Whereas most meteor showers are associated with comets this one is associated with an asteroid 3200 Phaethon.

Looking East Morning of December 21st

Donna the Astronomer

I am a keen astronomer lucky enough to live and work in Coonabarabran the Astronomy Capital of Australia! I am a ‘Drover’s Brat’ and discoverer of a couple of comets and asteroids. I operate Milroy Observatory and can show you how to best integrate dark sky experiences into your tourism, farm stay or AirBnB business.

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