Constellations, and why old people still join the dots

Children grow out of drawing dot-to-dot pictures at about the same time they start school. Mature adults later grow back in to drawing dot-to-dot pictures, by cataloguing constellations in the sky.

It is not the same type of dot-joining. This type of dot-joining is in the night sky, and it is far more open ended, because the dots in the sky do not come with numbers attached. Without the numbers, the result is left far more to creativity. Some constellations are extremely creative. Some constellations are so creative that almost nobody can actually see them for what they are supposed to be.

One example of dramatic creativity might be Canis Minor. Under normal circumstances anyone - including a mathematical genius - would struggle to construct anything other than a straight line between the two stars in the sky which are shown to be the constellation on most star maps. Somehow, the stargazers of the past managed to imagine a small dog. To be fair to them, ancient astronomers would also have been influenced by many dimmer stars which often go unseen except for in completely dark conditions.

The concept of constellations in the sky has been around for a very long time - probably as long as people have been looking up. People in many different societies over thousands of years have grouped the stars into pictures of what they knew. This might have been everyday things such as a pair of scales, or it might have been respected things, such as the gods they worshipped.

Different societies often saw the same patterns in different ways. For example, the constellation known today as Corvus, the Crow, was seen by the Arabs as a tent. Also, people in the northern hemisphere see most constellations upside down compared with the southern hemisphere. What was seen in New Zealand by Maori people as a cooking pot was translated to look like Orion, the Hunter, from the northern hemisphere.

As well as general categorising, many societies saw constellations in the sky as something more. For thousands of years, people have been looking to the constellations believing that the stars had an influence on human fortune. This probably arose from people noticing that the same star patterns were in the sky at the same times their crops were successful, and so on.

This would actually have been because the placement of constellations corresponds with the time of year, which is what dictates the seasons. Known today as astrology, it would have been common at the time for a king to consult a personal astrologer before going into battle to see what the stars would hold for the outcome.

The belief in astrology led to the establishment of twelve constellations to be known as the zodiac. These twelve constellations all lie on the ecliptic - the path in the sky on which the Sun, Moon, and bright planets all reside.

Astronomy makes efficient use of constellations. In astronomy, the sky is divided up into 88 official constellations. For historical flow, the official astronomy constellations have mostly carried through from mythology and astrology.

Each constellation is more than just a pretty picture made of sparkly dots - it is a designated area of the sky. There is not a part of the sky which is not included in an officially designated area surrounding one of the 88 constellations. Because of this, every star, galaxy, or other fixed celestial object can be designated as part of a constellation. These official areas can be seen on many star maps published both in books, and separately.

One of the funnest and easiest ways to learn your way around the sky is to learn constellations. For most people, learning pictures is much easier than trying to remember specific stars.

If you're interested in learning your way around the sky, start by getting hold of a star map of some sort. These can be found in a lot of astronomy books available at public libraries. Then start looking for constellations.

When you've worked out which constellations are currently in the sky, start looking for the easy ones. Simply look for star patterns which match those on your map. From the Southern Hemisphere, some of the easiest constellations to spot are Crux, Scorpius, and Orion.

Crux (better known as The Southern Cross) is easy to spot given a little time. The common way is to locate the two pointer stars to it - Alpha and Beta Centauri. Scorpius and Orion both have distinguishing features which make them easy to find. Scorpius has a big hook-shaped tail which stands out, and Orion is usually found by locating the three stars which form Orion's belt.

When you're searching, don't worry if you can't make out constellations straight away. Especially if the sky is polluted with light, many dimmer constellations might not be visible. Finding them takes some practice, but once you have spotted a constellation for the first time, it will be easier to find in the future.

Remember that a lot of constellations were dreamed up in the northern hemisphere, and as far as people in the southern hemisphere are concerned, those up north see everything upside-down. Because of this, making complete sense of some constellations from south of the equator might require some backward thinking.

Alternatively, you can always try inventing your own dot-to-dot pictures in the sky. This will probably not help to learn the constellations that most people go by, but it will give you an easy way to remember how the stars are placed in the sky.