With the moon currently waxing in the evening sky, we’re faced with the decision as to whether it’s actually worth going out and setting up the scope. Is it worth getting cold and tired when there’s so little to see? Well, there’s the moon itself, of course (and I hear from several stargazers that it’s endlessly fascinating …), or Jupiter (currently the only planet on show at a reasonable hour). What other stargazing options are open to us when the moon’s up and bright?
Bright star clusters, such as the Pleiades in Taurus, M44 in Cancer, M35 in Gemini, and M36, 37 and 38 in Auriga are clearly visible, though contrast and any faint nebulosity associated with them will be washed out by the moonlight. Another popular option (and the subject of this piece) is observing binary star systems (of which there are a great many). Some are difficult to ‘split’ – that is to see both stars in the pair – but others are visible to the naked-eye. Many binary systems contain brightly coloured component stars, and these are both beautiful and striking. In this piece I’m going to discuss a few such systems currently on view in the night sky.
Starting in the northwest, Ursa Major is, of course, one of the most recognisable constellations in the night sky. In the middle of the handle of the Big Dipper part of the constellation are Alcor and Mizar. 8-10 times magnification binoculars will easily split the two, and some – perhaps younger – people can even do so with the naked eye. The larger of the pair, Mizar, is actually made up of 4 stars, and Alcor 2, but with binoculars It’s likely you’ll only see the bright, white pair.
Just to the right of the Big Dipper is Canes Venatici, the lower star of which is Cor Caroli. Keen-eyed observers may be able to detect a hint of yellow in one of this pair. Again, moderate binoculars or a small telescope should be enough.
Swinging right and up into Leo, Algieba lies in the middle of the ‘sickle’ at the right of the constellation, and is made up of two giant stars, both yellowish in colour. This is a tight split, and reasonable magnification – in excess of 80 times – will be needed.
Iota Cancri is the uppermost star of the Cancer constellation, to the right of Leo. Sometimes described as the ‘Winter Albireo’, this really is beautiful. Like Albireo (in the constellation of Cygnus), one of the pair is a golden yellow colour, whilst the other is sapphire blue. Well worth checking out. Around 50 times magnification will show this pair clearly.
Turning right again we come to the constellation of Gemini. The star representing the ‘head’ of the upper twin is Castor. Although we see only two stars, the pair is actually comprised of 6! The brighter component is a rich golden colour, whereas the smaller is a bright white. Another tight split requiring magnifications of around 80 times and up.
Dropping down to the south, and just below and to the left of Orion is the constellation of Canis Major, and the wonderful double of 145 Canis Majoris. Another contender for the title of the ‘Winter Albireo’, this has been described as arguably the most colourful double star in the winter sky: bright citrus orange and royal blue in colour, and well worth a look. This is another easy split, with 50 times mag being enough to show the pair and the lovely rich colours.
Finally, those with a clear view to the northwest may still be able to spot the double star system Almaak, in the constellation of Andromeda. Another blue/orange pair, it may be a little low in the sky at the moment, but is well worth a look. An easy split for moderate binoculars and small telescopes.
All these binaries are relatively straightforward finds at the moment, and are just a handful of the many on view. I had a very enjoyable session recently exploring them in preparation for writing this piece, and I have to say, 145 Canis Majoris and Iota Cancri are really special sights; the rich and contrasting colours of the components being very striking. I think it’s amazing that so many of the seemingly single stars we can see are actually doubles (or triples, or even sextuplets), and the rich variety of colours is always a surprise. I sometimes find myself speculating on what the days and nights might be like on planets orbiting such systems.
For those interested in finding more spectacular binary star systems, Double Stars for Small Telescopes: More Than 2,100 Stellar Gems for Backyard Observers by Sissy Haas, or The Cambridge Double Star Atlas by Bruce MacEvoy are recommended.
What’s up?
Well, aside from the aforementioned clusters and binaries, Jupiter is still an obvious and bright target (in fact, apart from the Moon, Jupiter’s still the brightest thing in the sky). With the Moon currently waxing, and full on the 23rd, there’s little point in going looking for galaxies or faint nebula or a while. There are a couple of fantastic globular clusters coming into view low in the northeast, though. By around 10PM you should be able to spot M92 and the glorious M13 in Hercules. Even with the moon up they’ll be visible (as soft, fuzzy balls). We’ll have to wait till the moon’s out of the way, though, for the full effect.
Clear skies!
Kevin Quinn is an amateur astronomer based in Cerne Abbas. He is the proud owner of a ten-inch reflector, a small refractor, a case of eyepieces, and a couple of pairs of binoculars. He tweets via @CerneAstro, and blogs via theastroguy.wordpress.com.
©Kevin Quinn
