A light-year is how astronomers measure distance in space. -Light can travel 300,000 kilometres in one seconds! Light year is the distance that light travel can travel in one year. -Light can also travel 9,00,000,000,000 kilometers. -One light is about 10 trillion km. -Almost 300 years ago ,a Danish scientist named olaus roemer,was the fist man to estimate the distance light travels in a year -and using that he figure out the approximate speed of light!
