Night and Day

We have night and day on Earth because the Earth rotates or spins on its axis. (The axis is an imaginary rod or pole that passes through the North and the South Poles.) It takes a whole day or approximately 24 hours for the Earth to complete one rotation.

At any time in the 24 hours, half the Earth faces the Sun and has day. The other half of the Earth faces away from the Sun and has night.

Go here to see an animation of the Earth rotating on its axis.The Earth’s axis is tilted on an angle of 23.5 degrees. As it rotates, the part of the Earth facing the Sun has day, while the part facing away from the Sun has night.

When we look up, the Sun appears to move through the sky, rising in the east (sunrise), moving overhead and then and setting in the west (sunset). But the Sun never sets. The Sun does not move. It is the Earth turning that makes it seem as if the Sun is moving.

Go online to find a world clock that shows a day and night map of the world. http://www.timeanddate.com/worldclock/sunearth.html

The Seasons

We have different seasons on Earth because the Earth’s axis is not straight up and down, but is tilted on an angle of 25.3 degrees.

Each planet has a set path, called an orbit, around the sun. It takes one year for the Earth to orbit (move around) the Sun, just once. 
When the Earth’s axis points towards the Sun it is summer in the hemisphere tilted towards the Sun. (A hemisphere is the part of the Earth that is north or south of the equator). When the axis points away from the Sun it is winter in that hemisphere tilted away from the Sun. 

As the Earth orbits around the Sun, the part closest to the Sun has Summer.

There is more about the seasons on this kidcyber page

Acknowledge this page in your bibliography like this:
Thomas, Ron. & Sydenham, Shirley. Night and day [Online] www.kidcyber.com.au (2009)

October 2009 copyright © kidcyber [2009]