The month of December sees the winter solstice, the shortest day of the year. One could argue that for this reason, December is one of the best months of the year for stargazing. Although it gets very cold at night, so wrapping up warm is essential. This year the winter solstice occurs on the 21st December with only 7 hours 30 mins of daylight.
That day will be special for more reasons than one. Over the course of the month, the planets Jupiter and Saturn will get closer each evening. On the evening of the 21st December the two will be so close they will nearly look like one star. This event is known as the Great Conjunction. It is the closest they have appeared since July 1623, so this is a once in a lifetime event. This is of course a line of sight effect and they will still be, in fact, separated by 733 million km. Closer to the time, I will publish a detailed article on the conjunction.
Sun and Moon
| Date | Sunrise (Irish Time) | Sunset (Irish Time) |
|---|---|---|
| 01/12/2020 | 08:17 | 16:10 |
| 15/12/2020 | 04:34 | 16:06 |
| 31/12/2020 | 08:40 | 16:16 |
| Moon Phase | Date |
|---|---|
| Third quarter | 8/12/2020 |
| New Moon | 14/12/2020 |
| First quarter | 21/12/2020 |
| Full Moon | 30/12/2020 |
Planets
Mercury
Mercury is visible in the morning sky in first week of December just before sunrise. After that, it is too close to the Sun.
Venus
December is still a good month to spot Venus. It is getting lower in the sky but still prominent in twilight. It rises about 2.5hours before sunrise and will be extremely bright in the east. At the end of the month, it will rise about 1.5 hours before sunrise. It will be unmistakable.
Mars
Mars was at opposition on 13th October and will dominate the sky again through December. It will appear as a salmon – pink coloured star and will have already risen when the sky gets dark. It will start off in the South and move towards the west as the night goes on. It will be bright but will get dimmer as the month goes on.
Jupiter
Jupiter remains in the sky in November but is low in the west as darkness falls. It will be close to Saturn and will be the brighter of the two. As the month goes on the two planets will appear to get closer, ending with the great conjunction on December 21st.
Saturn
Saturn is visible close to Jupiter, it will also be low in the west as darkness is falling. It will be the dimmer of the two stars. As the month goes on the two planets will appear to get closer, ending with the Great Conjunction on December 21st.
Stars and Constellations
The above sky chart, from heavens-above.com is for 23:00 on 15/12/2020. You can click on the chart to open a new tab and bring you to Heavens Above. On this website you can generate a custom chart for the time and date you wish. The summer constellations are gone and the winter constellations are rising earlier each night.
To the northwest are Cepheus (the house), Cassiopeia (the queen), Andromeda and Pegasus (the flying horse). Andromeda is the location of the Andromeda galaxy which is the furthest object that can be seen with the naked eye. Although, you will need very dark skies to see it. Andromeda and the Milky Way galaxy are headed for a collision and will collide in an estimated 4.5 billion years.
In the south at this time of year, is the constellation of Pisces (the fish) and Aquarius (the water bearer). Mars is also in this area of the sky. Over in the east we have the winter constellations rising. You will see Taurus (the bull) which has a distinctive “V” shape and beside it the Pleiades or M45. Also visible will be Orion (the hunter). Most people are somewhat familiar with this constellation and will be able to pick out Orion’s belt. You may also be able to pick out the Orion nebula just below the Orion’s belt. This is a star forming region 1,344 lightyears away. Finally low on the eastern horizon is Sirius in the constellation of Cannis Major (the dog). This is actually the brightest star in the sky although we never see it at its best as it doesn’t rise very high from Ireland.
The Geminid Meteor Shower
The Geminid Meteor Shower peak happens in mid December each year. It is one of the best showers of the year, but occurs in the winter when it can get very cold. This year the peak is expected to happen at 00:50am (Irish time) on the 14th December. This is ideal this year as the Moon is new and won’t interfere. In absolutely perfect conditions, you could see up to 150 meteors per hour, although the real figure you will see will likely be lower.
To watch the Geminids, make yourself comfortable. A sun lounger or hammock is ideal. Also make sure you are warm, a sleeping bag can be very useful for this, as are hot drinks such as tea or hot chocolate! At this time of year you will need extra thermal layers, hats, gloves and scarves to make the experience enjoyable. You can look in any direction as the meteors will appear all of the sky.
Paul Smith 