ABSOLUTE BEGINNERS

CONSTELLATIONS

THE CONSTELLATIONS

Some of the brighter stars appear to form groups in the sky, these we call constellations. Most constellations were named a very long time ago by the Greeks or Arabs. People thought they could see the shapes of animals or their gods and named the constellations after them. Some honoured their gods or even famous people by naming groups of stars after them. In most cases it is very hard to imagine how they saw the shape that the star pattern is supposed to represent but we still use the same names today. Constellations are not necessarily associations of stars, some groups of stars are not groups at all but are just in the same line of sight as seen from Earth. If you were able to view what we call a constellation from some other part of the sky (say looking at Orion from a planet orbiting a star in Taurus) it would look very different from the way we see it from our vantage point here on Earth.

Some stars appear bright in our sky because they are close to us, others may appear bright because they are giant bright stars. Some dim stars are actually very bright but are a very long way from us. We as humans always like to put things into groups so that we can sort them out in our minds, we do this with everything even with people so we do it with stars too. We are also quite good at remembering shapes and we often have good imaginations so just as we can see shapes of rabbits and elephants in the clouds it is not surprising therefore that we see shapes or patterns in the stars, these are the Constellations. To find your way around the sky, one other constellation can always be used to find your bearings, this is URSA MAJOR the Great Bear or Plough. Ursa Major is always visible in the northern sky, it is bright and easy to find. It is shaped like a saucepan with four stars forming the square shape of the pan and three more stars forming the handle. The two stars of the pan furthest from the handle are called the pointers because an imaginary line drawn through them points to the north star called Polaris.

The pole star does not move in the sky and is always north of the point directly above us. By finding Polaris and turning around half a turn we will be facing south, and will then be able to use our star charts. The ancient Greeks recognised 48 constellations including the 12 constellations of the Zodiac. These constellations are those that the Sun Moon and planets pass through over the course of a year. An imaginary line drawn through these constellations and following the path taken by the Sun is known as the Ecliptic. Because of the tilt of the Earth the ecliptic is tilted at about 23° to the Earth's equator (Celestial Equator). Until the 1930's there was no standard list of constellations then the International Astronomical Union, astronomy's governing body, adopted the list of the 88 constellations we use today.

Constellations remain as the accepted system of identifying the various parts of the night sky. Of the 88 recognised constellations in the whole sky, 56 can be seen wholly or in part from Britain. Some equatorial constellations disappear below the southern horizon so only the more northerly parts can be seen. Other constellations are so far north that they can be seen all year as they appear to circle around the northern pole, these we call circumpolar constellations. Others can be seen for part of the year, then they dip below the horizon for the rest of the year. This is because the axis of our planet is tilted and the stars therefore trace out an arc across the sky.

There are about 100 constellations altogether with 56 are able to be seen from Britain and the rest of the northern hemisphere.  Some constellations are only just visible on the southern horizon so we may only be able to see parts of them.  To see which constellations are visible this month click on the month in the list below to see a chart of the sky. (Planets are not show on this chart so see What's up for the sky this month).

 Below is a list of the northern constellations in alphabetic order.  Some of these constellations have the meaning of the name included and some also have the names of well known stars which are located in the constellation. 

CONSTELLATIONS VISIBLE FROM BRITAIN

NOTE : Constellations shown in bold print are circumpolar from Britain.

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