Brought to you by Dr. Roy Gretton, Journal Editor of The Nottingham Astronomical Society.
Please note, the NAS new permanent venue for our main meetings on the first Thursday in the month. Nottingham Emmanuel School, Gresham Park Road, West Bridgford, Nottingham, NG2 7YF.
Welcoming the Winter Constellations
Winter can be grim in many ways. Colder temperatures, worse weather – often too many storms and too much rain – together with all those hours of darkness! On the other hand, when the sky is clear there’s a lot to be seen in the heavens. Probably the most famous and recognisable of the winter constellations is Orion the Hunter, who comes striding over the eastern horizon at 8pm in mid-November and at 6pm in mid-December. He will be due south and therefore at his highest at midnight in mid-December, and at 11pm on New Year’s Eve.
What makes Orion so distinctive is the line of three stars that make up his belt, and the two bright stars Betelgeuse (orange) and Rigel (blue-white) that mark his right shoulder and left knee respectively. Of course, the stars that make up a constellation in our sky aren’t necessarily close together in space. They are simply in a similar direction when viewed from Earth. Even so, many of the stars and gas-clouds of Orion are part of what we call the “Orion Arm” of the Milky Way, a spiral arm of our galaxy, sometimes called the Local Arm because our Sun is close to its inner edge. It is full of fascinating objects such as the Great Orion Nebula, which you can spot with the naked eye as a fuzzy patch in the Hunter’s sword. This nebula is part of a much larger system of gas clouds that almost fill the constellation.
The central star in Orion’s belt is called Alnilam and is classed as a “supergiant”, being over 300,000 times as bright as the Sun – and we think the Sun is bright! The lowest of the three belt stars is Alnitak, another supergiant, and near this is a feature called the Horsehead Nebula, a cloud of dark dust resembling the shape of an equine head silhouetted against a cloud of glowing hydrogen.
The Planets in November & December
As regards prospects for observing the other The Planets. Throughout November and December and into the New Year the planet Mars, undergoing its “retrograde moon” in the constellation of Taurus, will be wandering about to the north of Orion. If you look carefully you will be able to see Mars’ position changing from week to week as the Earth, orbiting the Sun in a faster lane, “overtakes” it. Mars will be at one corner of a triangle of bright orange “stars”, with Betelgeuse and Aldebaran (the Bull’s eye) at the other two corners. As November begins, they will form a roughly isosceles triangle with Mars at the apex, but in the following weeks Mars will move steadily to the right, such that by the first week of December a different isosceles triangle will have formed, with Betelgeuse at the apex. It won’t be until mid-January that Mars begins moving to the left again. The Red Planet will be at opposition to the Sun, and therefore closest to Earth and due south at midnight, on December 8th. Many amateur telescopes will be pointed at Mars this December!
Jupiter, glowing with steady light, continues to be the brightest object visible in the evening sky, apart from the Moon. Even at the end of December it won’t be setting until nearly midnight. The dimmer Saturn is now past its best, and will be setting at 9pm as December begins. Venus creeps into the evening sky in late autumn, but it will be so low down (24 degrees south of the celestial equator at the start of December) that it will be all but impossible to see. Mercury will be in a similar position, and so effectively unobservable.
Phases of the Moon
| Nov | Dec | |
| First Quarter | 1st & 30th | 30th |
| Full Moon | 8th | 8th |
| Last Quarter | 16th | 16th |
| New Moon | 23rd | 23rd |
