The zodiac is an imaginary band in the sky.The constellations of stars that lie along this band are known as the constellations of the zodiac
If you look up into the sky on a clear night,you will see millions of stars.If you look more closely,you will see how some stars make patterns and pictures.These are called constellations.A constellation that is easy to find is the little Dipper (Ursa Minor)
Many constellations are used as the signs of the zodiac.The word "zodiac" coms from the old Greek word for "animals" because many of the constellation look like animal.
Every star begins its life as a very thin cloud of hydrogen gas.As the cloud gets smaller,all the atoms of gas in the center get very hot,until finally the cloud begins to shine as a star.In fact,you don't see the star itself,you see the light that shines from it.
All star sare different colors,and some of them shine more brightly than others.The color of stars depends on its temperature.Some stars have atemperture of 1500 ํC.Other stars can be as hot as 100000 ํC.The hottest stars are white.
not all stars live for the same length of time.The life of star can very from a few million years to ten billion years.The small.dim stars live much longer than the very hot,bright ones.These burn out much faster.
A galaxy is a collection of millions of stars.The Earth,the sun,and the planets are all part of the Milky Way galaxy.Astronomers believe that there are 10 billion stars in the Milky Way.