Universe & ICT Grade -10
Unit -12 Universe Unverse: The huge space which contains every things i.e.stars, planets ,satellite, meteorites, comets etc. that exist is called the universe .The width of universe is about 100000 light years. Units of astronomical distance : There are three widely used units to express the astronomical distance : i)Light year: The total distance covered by a ray of light in the vacuum in one year is called light year .It is also called big unit which is used to measure the distance in the universe . Light year =c×t (Where c = velocity of light ,t= time taken) =3×10 8 ×60×60×24×365 =9460800 ×10 8 =9.46×10 7 ×10 8 m Therefore ,One light year =9.46×10 15 m ii)Astronomical unit : The distance between the earth and the sun is called astronomical unit .It is also called unit which is used to measure the distance in the solar system . 1 astronomical unit(A.U.)= 1.5 ×10 11 m or 1.5×10 8 km Solar system : The family of the sun includin