The constellations are the star groups we see in the night sky, and they were given their names many thousnads of years ago. The stylisation of the star groups into patterns bearing names such as Orion the Hunter, Leo, or simply the Scorpion, provides us with a very easy and convenient way to find our way around the sky.
At one time knowing these constellations, and their positions was very important. Navigation was, and still is based on the position of the stars, and the seasons were identified by what constellations could be seen, and where they were. We can still use these names and shapes to identify what we are looking at in the night sky.
Using the constellations almost like a road map, you can find your way from star to star. It’s best to go for the stick drawings, rather than using the beautifully drawn pictures of a hunter, or a lion. Although these drawings are great to look at, you are giving yourself a harder task in learning the constellations than you need to.
Get yourself a star chart, preferably a planetsphere, and find where the compass points are in the sky, then orientate yourself to face north. You need to dial in the date onto the edge of the chart; and this will give you the constellations that are visible to you at that moment. You can then orientate the chart by holding it above your head, so that it’s also pointing north. The chart will show the basic lines between the larger stars of the constellations, grouping them together, similar to a dot-to-dot book.
To keep yourself orientated you need to find the North Star. This is the one star in the sky which does not appear to move, and is also known as the Polaris. This star is part of the Ursa Minor constellation, and once you identify this star, you will then be able to identify the constellation. You are now on your way to getting around the night sky.
Using your imagination to extend the lines of the constellation of Ursa Minor on the star chart, can lead you straight to other constellations. Just draw this line in your mind between a bright star in Ursa Minor to a bright star in a nearby constellation. This will take you directly to the next viewing object.
If you are unsure about whether the star you see is actually in the constellation your are looking for, then there is a basic measurement you can use. If you stretch out your arm in front of you, with your hand flat against the sky, you can use your fingers as a distance guide. Holding your fingers outstretched, with your thumb on the Polaris, the distance between your thumb and your little finger is between 16 and 20 degrees. Another handy thing to know is that the width of one finger is about one degree.
Knowing these rough measurements is useful as you can now look at your star chart. You can see that it is marked with a grid that shows the degrees between the stars. Using your hand, you can translate the degrees on the star chart to degrees in the sky. It is not an exact measurement, but with a bit of practice, you will be able to confirm that you are looking at the right object.
The best tip of all for learning the constellations is to get outside at every opportunity, and observe the night sky. You don’t even need a telescope to learn the constellations, just a clear night and a bit of patience.