WHAT IS A CONSTELLATION?

Post by General Astronomy.

WHAT IS A CONSTELLATION? http://www.videojug.com/film/what-is-a-constellation What Is a Constellation? When you go outside on a dark clear night, look up into the night sky and see hundreds if not thousands of stars randomly spread across the sky - how do you tell one from another? The answer is you learn the constellations. The constellations are totally imaginary things that poets, farmers and astronomers have made up over the past 6,000 years (and probably even more!). The real purpose for the constellations is to help us tell which stars are which, nothing more. On a really dark night, you can see about 1000 to 1500 stars. Trying to tell which is which is hard. If you were shown a map of the world then you would easily recognise the continents and countries and would be able to pick out cities and towns. Well let's split the sky into continents, countries and cities. The constellations help by breaking up the sky into more manageable bits. For example, if you spot three bright stars in a row in the winter evening, you might realize, "That's part of Orion!" Suddenly, the rest of the constellation falls into place and you can declare: "There's Betelgeuse in Orion's left shoulder and Rigel is his foot." And once you recognize Orion, you can remember that Orion's Hunting Dogs are always nearby. Then you might recognize the two bright stars in the upper and lower left of the photograph as Procyon in Canis Minor and Sirius in Canis Major. The constellations change throughout the year. In winter and early spring we have Orion dominating the sky. His arch enemy Scorpio is high in the southern sky during the summer months. From the northern hemisphere Ursa Major or the great bear never disappears beneath the horizon. We have now broken it down into ‘the plough', ‘the chariot' or in the USA ‘the big dipper'. Follow the two stars at the end of the plough, known as the pointers and they point to the North Star. Follow them downwards and they point to Leo the lion. Using one constellation helps us find many more constellations. Let's go back to Orion. Follow the stars in the belt up past the star Betelgeuse in his left shoulder and we come across Castor and Pollux the two bright stars in Gemini the twins. Follow his belt in a line upwards and we find Aldebran, the eye of Taurus the Bull. There are 88 recognisable constellations in the sky. Some take a little more imagination than others to see them. The W shape of Cassiopeia, a beautiful lady sitting in a chair needs a lot of imagination. What about Pegasus, the winged horse, and Perseus ,the prince, all once famous names from mythology. Perhaps we spend too much time in front of a television to really let our minds run astray!