Sandra: what is rotation? Pilar: the earth is a sphere, which spins round and round. It takes 24 hours, a day to make one complete rotation. One side of the earth face the sun, while the other side faces away into space, it’s daytime and nighttime. Sandra: so, does sun rise during the day and the moon rises at night? Pilar: well, it’s not like that at all. The moon is the only satellite of the earth and although it does not have its own light, the moon shines because its surface reflects light from the sun. Sandra: so, how his is the moon, the sun and the earth? Pilar: if we compare them with a ball, the sun would be a basketball ball, the earth a soccer ball and the moon with a marble. Sandra: wowww, how his is the sun and how small is the moon! Thank you for all your help and teaching us a little more about the solar system. Pilar: thank you and I wish I helped you a lot.