Ch-1: The Earth and Solar system
Celestial bodies: The sun, moon, stars and all other objects shining in the sky are celestial bodies. Stars: Stars are very big celestial bodies made of gases. They have their own heat and light and emit in large amounts. Our sun is also a star, near to earth. So that we can feel heat and light of sun but not other stars as they are very far away from earth. Constellations: Constellations are different groups of stars form various patterns in the sky. Ursa Major (Big Bear) is one of such constellations. Saptarshi is the part of Ursa Major Pole Star: Pole star is also known as 'North star'. People used to determine directions during night with help of stars, particularly Pole star indicating north direction. It always remains in same position in the sky. We can locate position of pole star with the help of Saptarshi constellation. Planets: Greek work 'Planetai' represents "Wanders". Planets are celestial bodies shine by light of other stars. They do not h...