(Originally printed for local newspapers Feb 2006)
As we come out of winter, more astronomers are prepared to leave the warmth of their homes to look at the splendours of the Universe. Shame on you! Winter provides some of the best opportunities to see these wonders! Nevertheless, spring means that summer is not far ahead, and that means more pleasant viewing conditions.
While a lot of the winter constellations offer more to see within them, most of them will remain visible for a month or two yet. Orion, Gemini, Leo, and Virgo, all rich with nebulae, star clusters, and galaxies, will still remain on view till April or May at best. Not forgetting the circumpolar constellations, all these have at some stage, something brilliant worth aiming a telescope at.
It is also worth to note that by now, many people who received a new telescope for Christmas recently, will be getting used to using their new toy. But, there is still a lot to learn in maintaining and maximising the use of that toy. For now, let me talk to you about what to look for. And since many people availed of the telescopes on offer before Christmas such as the Skylux 70mm, and the Meade ETX-70, I’ll start with these telescopes in mind. Also, have your star atlas nearby!
If you go out tonight (or any night) when its dark and look up above, you should see three bright stars in a bent line. They cover an area about the same as your flat hand held in front of your eyes at arms length. One of the stars will appear a little brighter, and more white that the other two bright blue stars. This white ‘star’ is in fact Saturn, while the other two are Castor and Pollux, the heads of the twin brothers of Greek mythology that make up Gemini. This constellation actually looks like two stick men standing side by side holding hands.
Saturn is tilted favourably towards Earth in such a way that the rings are unmistakeable, even in a small 70mm refractor telescope. If you have one or similar and look at Saturn, you should see the disk surrounded by the rings as a solid bright shape. Larger telescopes will show a little more detail, with an 8 inch reflector and larger showing slightly more colour, and the famous Cassini Division – a large gap in the rings. No one forgets their first look at Saturn in a telescope!
Below Gemini towards the horizon is a very bright star, twinkling from blue to white. This is Sirius, the brightest star in the sky, and lies in the constellation Canis Major, the Greater Dog. If you focus your telescope on it and watch it for a minute, you will see it goes through many changes in colour from blue to red to white to orange. This is not a natural effect of Sirius – it is an effect caused by its light going through our turbulent atmosphere. If we had no atmosphere, Sirius would be brighter, and almost pure white.
Soon, Sirius will move closer to the horizon and fall below, only to be seen by those further south of our latitudes until it comes into view again next November.
Back at Saturn
To the left of Saturn and moving away from Gemini is a small constellation called Cancer, The Crab. Within Cancer there is a small cluster, known as Praesepe, or M44 - The Beehive Cluster. This cluster is easily seen from a dark observing site with little or no light pollution. More experienced observers will see it from towns or suburbs by knowing where to locate it. This cluster is composed of many tens of stars held loosely together by their own gravity – an Open Cluster. It lies within our own Milky Way galaxy, but can be thought of as a mini galaxy within it.
With the naked eye, you can see a couple of stars within a small cloudy area. If you point your telescope at this tiny cloud, you will see many stars within the cluster. The bigger the telescope, the more stars you will see. You can try and count them, but you’ll be there for a long time doing so!
Moving on, if you draw an imaginary line from Saturn to The Beehive and keep going, you will come to the constellation of Leo, The Lion. You have probably heard of this constellation in recent years as the source of the famous Leonids Meteor Shower every November 17th. Leo itself takes on the shape of a lion sitting on the ground. The front paws and head make a shape know as The Sickle. It is just off the sickle that the radiant for the Leonids lies.
At Leo’s front paw is a bright blue star. This is Regulus, meaning Prince, or Heart of the Lion. Along Leo’s flank moving left, you pass a star marked simply as theta Leonis. A small bit further on again, you come to another bright star called Denebola, marking the tail end of Leo. With your telescope, if you slowly sweep the area half way and a little below between Regulus and theta Leonis, you might encounter some very faint small blurry objects. If you have nice viewing conditions and keen eyesight, you should see 3 really. These are distant galaxies M95, M96, and M101. A little to the left and below theta Leonis itself are 3 more galaxies, M65, M66, and NGC 3628. If you can spot these with your 70mm refractor, imagine what you could see with a 6 inch reflector and larger.
The Messier Catalogue
Where do we get the M-numbers from? We credit this to the French astronomer, Charles Messier (1730-1817). In a bid to try and find comets with a small and rather poor refractor, he came across many objects not catalogued before. Since they did not move, yet he did not have the optical power to see what they really were, he compiled a list of 110 objects he found not to be comets. These were numbered and given an ‘M’ prefix. This catalogue is known at the Messier Catalogue.
Not far away from the left and below of Leo is a brilliant steady white point of light. This is Jupiter, the largest planet in the Solar System. This is a favourite target among amateur astronomers, even those with nothing more than a pair of binoculars. From night to night, you can see 3 or 4 of Jupiter’s moons big enough to be seen from Earth. In order of size they are Ganymede, Callisto, Europa, and Io.
If you manage to get a couple of clear nights in a row, spend at least a few minutes each night looking at Jupiter. You will notice that these 4 tiny points of light, even in binoculars, move around Jupiter. With your 70mm refractor, you should be able to see 2 coloured bands or cloud belts across Jupiter. A larger telescope will show more. A larger telescope will also show the Great Red Spot. This massive storm, 3 times as big as Earth, was first seen by Galileo over 400 years ago, and is still bellowing! If you look at Jupiter a few hours apart, you will notice the Great red Spot moving across the planet. It completes one revolution every 9.8 hours.
(Paragraph here mentioned about the forthcoming TAS meeting at the time in order to find more info.)