Day and night are caused by the steady rotation of the Earth. The Earth does one complete rotation in 24 hours.

The axis of the Earth is an imaginary line between the earth's poles. The Earth rotates (spins) on this axis. The Earth's axis is not straight up and down, but tilted of an angle of 23.5 degrees.

Our home plane Earth is the third planet from the sun. We have one moon, liquid water, and life! Earth is the only planet we know suitable for life, so let's take care of it, shall we? Learn about the layers of the earth, what our atmosphere does for us, and why years and days are the lengths they are.

The angle and the direction of the Earth's tilt on its axis does not change as we orbit the Sun. This means at times the south pole is tilted towards the Sun and the north pole is tilted aways from the Sun. Approximately six months later the north pole will be tilted towards the Sun and the south pole will be tilted away.

These changes affect the amount of sunlight hitting the Earth's surface in each hemisphere and causes the seasons.

Key words: equinox, solstice

Did you know that the Sun’s light shines differently on Earth at different times of the year? In this visualization watch as the Earth orbits the Sun, rotating, like a slightly tilted, spinning top. This rotation changes the angle at which sunlight hits the surface of our planet, creating the different seasons we experience here on Earth. Can you see how sunlight at different times of the year changes the productivity of life on land and in our oceans?

The International Space Station is as far as humans go in space these days, but it is at just the right distance to capture astonishing images of Earth.