By:

Saviz Safizadeh

The Earth is the 3rd planet in the solar system after the planets

Mercury and Venus.

• The Earth rotates around an imaginary line. This line passes through the North and the South poles. Scientists call this line the Earth’s axis of rotation.

The Earth turns on its axis. This movement takes 24 hours and is the reason behind day and night.

The Earth also moves in space in a circular motion around the sun. Scientists say the earth orbits or

revolves around the sun.

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* It takes the Earth 365 days or one year to fully orbit the sun.

* The Earth rushes through space orbiting the sun with a speed of 108,000 Km/hr or 67,000miles/hr.

• The Earth’s axis is tilted by 23 ½ O

What are the Reasons for the What are the Reasons for the Seasons?Seasons?

There are 2 reasons for all 4 seasons:a) The Earth’s motion on its orbit

b) the Earth’s inclined axis

On the first day of Spring …* the Sun shines directly over the Equator.• There are an equal number

of hours of daylight and darkness.

• Twice each year (March 20- 21 and September 23), the sun directly crosses the equator and day and night are equal everywhere on earth. These are called the “Vernal” and “Autumnal equinox” During

• the vernal equinox in the northern hemisphere, the southern hemisphere is in autumnal equinox.

In the northern hemisphere, the summer solsitice begins on the last day of spring as the north pole is most tilted

toward the sun.

• The winter solstice begins on the last day of fall as the north pole is most tilted away from the sun.

After a long, cold winter, everyone awaits the arrival of the new season.As the earth warms up, plants begin to grow and animals leave their shelters.

For humans, spring is a time of work as well as celebrations. People have celebrated this “new day” in many cultures:

* Until 1582, most of the Roman empire and the Medieval Europe celebrated their new year in March.

Ostara, Nowrooz, Easter, Tel Shemesh are only some of many celebrations of the rebirth of nature and the renewal of life.

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Bibliography:• http://www.1ststeps.org/Science/seasons.htm, October 12, 2007.• http://en.wikipedia.org/wiki/Solar_System• http://www.ecology.com/archived-links/earths-rotation/index.html• http://spiff.rit.edu/classes/phys301/lectures/sunmoon

• http://www.zoomschool.com

• http://upload.wikimedia.org/wikipedia/commons

• http://cse.ssl.berkeley.edu