I hope you managed to see the planets Venus, Saturn and Jupiter all in a line just after sunset on one of our clear nights. On Sunday 28th November I spotted Venus bright in the sky just as the sun was setting from my armchair in my lounge! I did have to get up off my bottom to spot the other two as the skies darkened although Jupiter is so bright that you cannot miss it either.
The following chart represents the night sky at 11.00pm GMT on the 8th of December and at 10.00pm GMT on the 23rd December. To use the chart, face south at the appropriate time with the bottom of the chart towards the southern horizon and you will see the stars in the chart. If you are observing a little earlier in the evening then the view is shifted 15 degrees eastwards for every hour before the specified time.
This month the focus is on the constellation Orion- The Hunter. It’s my favourite constellation because of its distinctive shape and because it appears to have everything. It doesn’t take much to visualise a hunter from the stars in Orion and what stars they are! Orion’s right shoulder is represented by the star Betelgeuse, a variable red supergiant, varying in magnitude from about 0.3 to 1.2 and the 7th brightest star in the northern hemisphere. If Betelgeuse were to replace our sun it would reach out all the way to the orbit of Jupiter. It also has the potential of going supernova but of course we do not know exactly when. Then, representing his left foot, is the blue supergiant Rigel the 5th brightest star in the northern hemisphere with a magnitude of 0.2. Between these stars is a line of three stars going from south east to north west and they represent Orion’s belt and at magnitudes of around 2 they are unmistakable. Less bright but still visible to the unaided eye is Orion’s sword hanging from his belt. The bottom star of the sword should be visible in good conditions and above this is a misty fuzzy patch which is the Orion nebula (aka M42) where star formation takes place. Try to observe it through binoculars or a telescope if you get the chance.
The rest of this blog is about stars and there will be more to say about the constellations in which they lie next month. Because it is so easily recognisable, Orion is a good starting point for finding your way about the night sky during the winter months and especially for the stars we discussed last month. Follow a line from Orion’s belt to the upper right, underneath the star Bellatrix representing his left shoulder, and you will find the star Aldebaran, a giant red star of magnitude 1 and the 9th brightest star in the northern hemisphere. Continue the line beyond Aldebaran and you find the star cluster- The Pleiades or Seven Sisters.
Having followed the line to the Pleiades turn ninety degrees to the north and the bright star you see is Capella, in the constellation Auriga- The Charioteer, lying directly above Taurus. It is the 4th brightest star visible in the northern hemisphere and shines at magnitude 0.1.
Now follow a line from Orion’s belt to the south east and you will find the brightest star visible in the night sky, Sirius- the Dog Star. At magnitude -1.4 it is twenty three times more luminous than the Sun and a mere 8.6 light years distant. Sirius is part of the asterism known as the Winter Triangle, formed in conjunction with Betelgeuse and Procyon which lies due east of Betelgeuse. The white star, Procyon, is the 6th brightest star visible from the northern hemisphere so it is little wonder that the Winter Triangle is something to behold. It is outlined in yellow in the chart.
We finish this month with another asterism- the Winter Hexagon. It is roughly centred on Betelgeuse and comprises the stars Procyon, Sirius (both in the Winter Triangle), then continuing anti-clockwise, Rigel, Aldebaran, Capella and Pollux. It is outlined in red on the chart. You can enjoy viewing all these throughout the coming winter months as they make their way westwards in the evening sky.
Something to look out for
A solar eclipse takes place on Saturday 4th December but unfortunately it will not be visible from Europe. Look out for coverage in the media because it is always good to see.
Having witnessed the planets aligned last month there is a chance to see each one in turn, Venus, Saturn and Jupiter have a close approach with the Moon on the 7th, 8th and 9th of the month respectively.
Finally the December solstice is on the 21st.
The clocks have gone back again so there should be more opportunities to enjoy the winter sky in the darker evenings. It has been good watching Jupiter and Saturn in the evening sky, especially the former as it shines so brightly. Unfortunately my attempts to see their close approaches to the Moon have been thwarted by clouds. Still there will be another chance this month.
The following chart represents the night sky at 11.00pm GMT on the 8th of November and at 10.00pm GMT on the 23rd November. To use the chart, face south at the appropriate time with the bottom of the chart towards the southern horizon and you will see the stars in the chart. If you are observing a little earlier in the evening then the view is shifted 15 degrees eastwards for every hour before the specified time.
On the right hand side of the chart there is part of the constellation Andromeda and the two smaller constellations Triangulum and Aries which we mentioned last month. But we will use our old favourite Cassiopeia as our guide because you cannot fail to see it. Remember you don’t have to wait till late in the evening to observe these, make use of the earlier dark skies and look more towards your eastern horizon.
Look to the south east of Cassiopeia and you find, lying in the Milky Way, the constellation Perseus- named after the hero in Greek mythology. Again it is difficult to recognise a human shape but the lines above the star Mirphak represent his right arm and sword while the bright star Algol represents his left hand holding the head of his victim. That is enough of the gory details. Mirphak is a 1.8 magnitude yellow supergiant while Algol is an eclipsing binary varying in magnitude between 2.1 to 3.4. There are another five stars around magnitude three or brighter making Perseus a prominent northern constellation.
To the left of Perseus is the constellation Auriga- The Charioteer. It is easily identified because it contains the star Capella, the 4th brightest star in the northern hemisphere, at magnitude 0.1, and ‘only’ 42 light years from Earth. Again it is a binary system composed of two yellow giants. Auriga is in the rough shape of a pentagon although the bottom star Alnath is actually in the constellation Taurus.
In fact the constellation Taurus- The Bull, is our final constellation this month, lying directly below Auriga. It is one of the oldest constellations having been recognised as early as Babylonian times. It is also one of the constellations of the zodiac. Its brightest star is Aldebaran a red giant of magnitude 1 and readily recognisable because of its colour, supposedly representing the red eye of the angry bull. The two lines with Alnath at the top of the upper one represent the bull’s horns. The ‘V’ shape to the right of Aldebaran represents the face of the bull and is an open star cluster called the Hyades. The more famous open cluster, the Pleiades or Seven Sisters, lies to the north west of Aldebaran in the direction of Algol. The Pleiades is one of my favourite objects to view with the unaided eye and I recall watching Venus pass close to the Pleiades during the spring of 2020.
Something to look out for
Saturn and Jupiter are the gifts that keep on giving as they both make another close approach to the Moon on the 10th and 11th of November respectively. There will also be a partial eclipse of the full Moon on the 19th November but we are not well located for viewing it as the Moon will be close to the horizon and will set partway through the eclipse which takes place between 7.00am and 9.00am.