Skylights: Winter 2013 - 2014
Despite the fact that it is cold, the winter is the best time to look at the night sky. With the Sun at low declination, it gets dark earlier and the nights are darker and longer. But for us city dwellers, there is still the problem of increasing light pollution to spoil our view of the night sky. The winter is also a good time because the winter sky features some bright stars and some easily recognised constellations. Also, at this time of year, the ecliptic (the apparent path of the moon and planets) is high during the night time.
Towards the south we can find the constellation of Orion the mighty hunter, easily recognised by the three second magnitude stars, almost in a straight line that marks his belt. The top star Mintaka delta Orionis, is very nearly on the celestial equator. Above and to the east is the red first magnitude star Betelgeuse. Betelgeuse is a red giant, so large that if it were at the centre of our Solar System, Mercury, Venus, Earth and Mars would be inside it! Diagonally below Orion's belt and to the west is the blue/white first magnitude star Rigel. Rigel is a massive Supergiant, over 50,000 times as luminous as the Sun and some 880 light years distant. Below Orion's belt is situated M42 the Great Orion Nebula. Under clear dark skies, the nebula is just visible to the naked eye. Binoculars show it as a faint misty patch and a telescope can reveal quite a bit of structure, but long exposure photography reveals its true nature. It is a vast cloud of dust and gas with billows of glowing red nebulosity illuminated by the stars embedded in it. It is 1600 light years away and it is the birthplace of stars and possibly forming planetary systems.
Above Orion and to the west is the zodiacal constellation of Taurus the Bull. The brightest star in Taurus is another red star Aldebaran. To the west of Aldebaran is the open star cluster the Hyades, a fine sight in binoculars. Higher up and further west, is yet another star cluster - the Pleiades. Sometimes called the Seven Sisters, the Pleiades are easily visible to the naked eye as a little glittering patch. Keen eyesight may show six or seven stars, a pair of binoculars will reveal dozens, and a telescope will show as many as 400 stars in the group. Long exposure photographs show the pale blue nebulosity that surrounds the cluster. All the stars are hot blue stars, indicating that the cluster is young. On ancient star maps, the Pleiades are shown situated just below Perseus' knee. Perseus is fairly easy to recognise as it is just below the familiar 'W' of Cassiopeia. Perseus' brightest star is Mirfak and it is situated in a lovely star field, best seen in binoculars. Higher up between Mirfak and Cassiopeia, we can find the Double Cluster. This is one of the jewels of the heavens. Two densly packed star clusters set against the sparkly background of the Milky Way, a beautiful sight in a telescope on a clear dark night.
Almost overhead (zenith) is the first magnitude stars Capella, the principal star of Auriga, the Charioteer. Capella is circumpolar, so it never sinks below the horizon from our latitude. The Milky Way, sweeps through Auriga (if only we could see ir)and there are some fine star clusters, M36, M37, and M38, set against the background stars of the Milky Way, superb views in a telescope. The Milky Way just clips the western end of Gemini the Twins, marked by the two first magnitude stars Castor and Pollux. Castor, alpha Geminorum, is a complex star system. In moderate sized telescopes, Castor is seen as a binary star. the two main components orbit oneanother every 380 years. Large telescopes show a third fainter companion and all three stars are spectroscopic binaries. This year, Gemini plays host to the planet Jupiter shining brightly below Castor & Pollux. It is well placed for onservation this winter. Situated in the 'tail' of Gemini, is yet another fine star cluster M35.
Below Gemini, just above the celestial equator is the bright star Procyon, the principal star of Canis Minor the lesser Dog. Procyon is fairly close to us at just about 11 light years away and it has a tiny companion, a White Dwarf which orbits every 40 years. In this respect it is similar to Sirius, the brightest star in the sky. We can't miss Sirius, it can be seen low down to the east of Orion, sparkling away just above the southern horizon. Sirius is the main star in Canis Major the Greater Dog and at just 9 light Years distant, it is fairly close by. Sirius also has a White Dwarf companion called Sirius B. Sirius B is just 1/400th of our Sun's diameter, yet it has almost the same mass! Its density is an incredible 100,000 times that of water and a teaspoon full of Sirius B would weigh hundreds of tonnes! There are some beautiful and wonderful objects to be found in the winter skies.
Of the planets, Mercury Is too close to the Sun for observation. Mars is now rising later in the evening, situated just below Leo and Venus is gradually rising above the south-western horizon to become a bright early evening object. Jupiter is well placed for observation just below Castor and Pollux in Gemini. Saturn is now behind the Sun and therefore unobservable. Uranus is situated on the borders of Aquarius/Pisces available in the early evening in December and Neptune will have set by the end of November.
The Moon is one of the most impressive sights through a telescope. Even in a pair of binoculars much detail can be seen. The best times to view the Moon is about 3 days before and after first quarter, when the Moon is in the evening sky. Also there's the added bonus that the terminator (line between light and dark) is visible and we get some spectacular views of the lunar surface seen in high relief. But at this time of year the moon is well positioned as the ecliptic is high in the night sky.
|Phase||Full Moon||Last quarter||New Moon||First quarter|
Comets are also sometimes visible and can produce incredible public interest, and right now we had hoped that Comet ISON would be putting on a spectacular show. But, as we all know, Comets are renowned for being untrustworthy. At the beginning of the year ISON was predicted to possibly become the 'Comet of the Century' but it isn't, it is just a faint smudge only visible in binoculars. Our best chance of seeing it will be just before Christmas, that is if it survives its close encounter with the Sun. Then ISON will be moving swiftly northwards, gaining altitude but at the same time becomming fainter. On December 20th, it will pass between Hercules and Corona Borealis and should be visible in binoculars as a fuzzy patch at about 5th magnitude. But, nothing is certain; it just might flare up suddenly and give us a nice Christmas present - comets are like that. In fact at the moment there are 4 comets in the sky - ISON, Encke, Linear and Lovejoy, but all of them are faint objects which are difficult to locate and observe.
We have observed many comets in the past like Comet Halley (1985-86) and Hale-Bopp (1997)was so far the best in decades. In 2005 Comet Machholz was visible and Comet McNaught scudded through the northern sky in January 2007 and was easily accessable to the naked eye, albeit for just a few days. Normally none can be seen with the unaided eye at any given time but this can change. This was certainly the case with Comet Holmes which increased its brighness by a million times in October 2007 and remained visible to the naked eye for many weeks. To stay abreast of any new comets, sign up for our news service.
Most of the phenomena above are reasonably periodic. But there are also sporadic events which we can see through the Cooke telescope like eclipses or even novae and supernovae (Please). So keep your eyes on the skies or let us do it for you and you might get to look at some rare, beautiful and profound phenomena.
Last modified: Nov 17 2013 /DGD