Saturday, October 6, 2012
Friday, October 5, 2012
Thursday, October 4, 2012
Why do we have day and night?
We have day and night because the Earth rotates. It spins on its axis, which is an imaginary line passing through the North and South Poles.
The Earth spins slowly all the time, but we don't feel any movement because it turns smoothly and at the same speed.
How long does it take the Earth to turn around?
The Earth takes a whole day (24 hours) to makea complete turn.
Why is the Sun in the sky at some times and not at other times?
At any time half of the Earth faces the sun. This part has day. The other half of the Earth faces away from the Sun. It receives no light. It is dark and has night.
The sun is the source of light for day.
The Sun does not move. It seems to move across the sky starting in the east in the morning, moving toward the south at noon, and then toward the west as the day ends.
It is the Earth turning that makes it seem as though the Sun is moving.