What causes the change from night to day and how long is a day on earth?
Wow, that seems like an incredibly simple question. Night – that part of the earth in its own shadow from the sun’s light. Day – that part of the earth facing the sun, so it receives the sun’s light. At any one moment, exactly half of the earth has day and the other half has night. And every place on earth has the exact same amount of day and night when averaged over a year. A day is equivalent to one rotation of the earth, just under 24 hours. You need to imagine the earth and sun in 3D, it is rotating at 1 rev per earth day around its own rotational axis, and it also revolves around the sun once every earth year. Get a book on the solar system, if you don’t understand this concept its much easier to visualize from a drawing. PS, most five year old children can explain this to you.
