Martin Lunn gives his fascinating insight into what we can see in the night sky this December - clear, cold nights permitting.

Read his report and then go and have a look for yourself. You will be amazed at your can see on a clear night.

GET set for the Geminid meteor shower; a shooting star spectacular for the end of the year.

Many people look out for the annual Perseid meteor shower, which occurs in August. It is, however, not the most spectacular meteor shower.

The Geminids hold that title and they can be seen this month. The Geminids reach maximum on the nights of December 13 / 14 and 14 /15 when up to 120 meteors per hour might be seen.

Meteors are connected with comets. As a comet, which is essentially a dirty snowball, travels around the Sun, it leaves a trail of dust behind it. If the Earth happens to pass through such a trail we see a meteor shower.

The Earth passes through many such streams each year. Some of the meteor showers are spectacular; others less so, but they are all predictable. The Geminids are so called because the meteors all seem to come from the constellation of Gemini the Twins. They are special because they are associated not with a comet but with an asteroid called Phaethon.

The pieces of dust produced by asteroids are slightly larger than those produced by comets and because of this they travel through the Earth’s atmosphere more slowly, making them much brighter than the usual meteors.

The Geminids travel at about twenty miles a second compared to most other meteors, which travel at around forty miles per second. The dust particles burn up due to friction in the Earth’s atmosphere.

If there are no clouds we should be in for a spectacular event. If you see a meteor or shooting star in the sky, you know what you have to do: make a wish!

This month all the main signposts in the night sky are on view: the Plough; Orion; Cassiopeia and the Square of Pegasus.

The Plough can be found in the North East, standing on its handle with the pointers (the two stars furthest from the handle) pointing to the North Star.

Orion is not yet at its best but it dominates the south eastern part of the sky. Capella, in the constellation of Auriga the Charioteer, has not yet arrived at the zenith but it is very high up.

With regards to the Summer Triangle of stars, only Deneb can be found, low in the west. The Square of Pegasus now can be found in the south west. The bright star Fomalhaut in Piscis Austrinus, the Southern Fish, has now set.

The constellation of Perseus is now high in the sky, so this is a good time to find the star Algol which marks the eye of the Medusa slain by Perseus.

Medusa was the creature with hair made from snakes, and one look at it would turn the observer to stone. The star names are Arabic and the word Algol means the ‘Winking Demon’. Algol is what is referred to as a variable star. Its light changes in brightness over a period of a few days, hence its name.

These light variations, which were first explained by the deaf astronomer John Goodricke who lived in York in the 1780s, are very regular and predictable. It was Goodricke who suggested that there were two stars eclipsing each other. It wasn’t until around one hundred years after his death that astronomers were to prove his ideas correct.

While talking about events in the December sky people sometimes think about that most famous of all stars, The Star of Bethlehem. Many people have wondered what it could have been. I have my own ideas about the star but I expect it will always remain a mystery.

The Planets in December

The evening sky will be stolen by the planet Venus, ‘The Evening Star’ as it is often called. Venus can be seen low in the sky but because it is so bright it makes a spectacular December evening sight. Venus will set two hours after the Sun at the beginning of December and one hour after towards the end of the month.

Some people might think Venus is the ‘The Star of Bethlehem’ but I am afraid this is not the case.

There will be a rare chance to see Mercury this month because between Christmas Day and New Year’s day the innermost planet can be seen low in the western sky beneath the bright white dot of the planet Venus.

The two gas giants Jupiter and Saturn which have been with us all year are now in the twilight sky and will be difficult if not impossible to see.

The other naked eye planet, Mars, is in the pre-dawn sky before the Sun rises and will be very difficult to see.

Meteor Showers

After the Geminids another meteor shower, the Ursids, peaks on the night of December 22nd / 23rd when, usually, about ten meteors per hour can be seen. The Ursids appear close to Christmas and with our focus on celebrations they are poorly observed.

The Ursids have been known to produce outbursts of large numbers of meteors in the past so it is worth watching out for them. The Ursids appear to come from the constellation of Ursa Minor, the Small Bear. The North Star is actually the end star of the tail of the small bear.

Phases of the Moon for December

New Moon 4th First Quarter 11th Full Moon 19th Last Quarter 27th

The full moon in December is known as the Before Yule Moon. The feast of Yule occurs on the night of December 21st which is the day of the year when the Sun is at its lowest in the sky and produces the shortest period of daylight of the year.

This date can vary from year to year by a day or so.

A long time ago people watched for the full moon in December; they then had from that date until the feast of Yule to chop down a Yule log from the forest in readiness to burn it from the feast of Yule for twelve nights.

Today of course the Yule log has turned from firewood into a cake!!

The winter solstice this year occurs on December 21 when the Sun lies at its lowest point in the sky.

It is the shortest day of the year and the longest night. This is when winter officially begins in the northern hemisphere and summer begins in the southern hemisphere.

Due to the current coronavirus there will be no meetings of the Earby Astronomical Society until further notice.

I would like to wish all the readers of the Craven Herald a very merry and peaceful Christmas and a very Happy New Year.