Earth&Seasons

This is our planet Earth.

It has a shape of sphere, like a ball.

The equator divides the Earth into two halves.

The northern half is the Northern hemisphere.

The Southern half is the Southern hemisphere.

Europe and Asia are both in the Northern hemisphere.

Australia and the third Affrica are in the Southern hemisphere.

The Earth moves in two ways.

First , is spins or rotates.

It rotates around the axis.

The axis is a line through its center.

It takes the Earth 24 hours to complete a rotation.

That is the length of one day.

Second , the Earth travels around the Sun.

It takes about 365 days for the Earth to go around the Sun.

That is the length of one year.

Its average speed during the year is about 30 kilometers per second.

The Earth's axis is not perpendicular to the Sun.

The Earth's axis is tilted.

It is tilted at an angle of around 23.5 degress.

This tilt causes the seasons of the year.

During  part of the year, the Northern hemisphere is tilted toward the Sun.

When the Northern hemisphere is tilted toward the Sun, it's summer.

When the Northern hemisphere is tilted away from the Sun, it's winter.

This is why the seasons are opposite for the northern and southern hemispheres.

When it's summer in Australia, it's winter in Europe.

What wound happen if the Earth's tilt were different than it is now.

If the Earth's tilt were larger, summers would be hotter.

If the Earth's tilt were smaller, summers would be cooler.

If the Earth has no tilt at all, there would be no seasons.

Therefore ,the angle of a tilt is very important for life on Earth.

The Earth is 93,000,000 miles from the Sun.

The Sun is at the center of our solar system.

Our solar system has several planets which orbit around it.

Our planet is the third planet from the Sun.

If the Earth were closer to the Sun ,out planet would be hotter.

If the Earth were farther from the Sun ,out planet would be colder.

Therefore, the distance bwteen the Earth and the Sun is very important.