Some details about stars

Stars 

             A star is a huge ball of glowing gas held together by gravity. It continuously emits light and heat. The sun is the nearest star to the earth. So, sun appears large compared to other stars. Actually, many of the stars are much larger than the sun. But these stars appear like a point because of large distance from us. All stars shine day and night. But we can see the stars only when the sky is dark and clear. During the day, the stars are not visible because of the glare of bright sun light.

              All stars including the sun move around some celestial body or a group of bodies with high speed. In spite of their great speed, the distance between any two stars does not seem to change when viewed from the earth. This is because the stars are very far away from us. If any change in distance occurs between  them they do become perceptible in a few years or even during one's life time.

              Everyday the sun and all other stars seem to move across the sky rising in the east and setting in the west. The rising and setting comes from the rotation of the earth from west to east about an imaginary axis that passes through its centre. However, there is one star, which appears stationary to us. This star is known as pole or Polaris. 

             A star is made up of mainly hydrogen and helium gases. The great mass of a star makes the temperature at its centre high enough for a nuclear reaction to produce energy. This energy released by the reaction keeps stars shining.