The Earth’s Movements
The many lifeforms living on the Earth are in large part dependent on heat and light from the Sun. By converting hydrogen into helium, the Sun generates an enormous amount of energy every second of every day. Although there are small variations in the intensity of this energy, for the most part, the heat and light generated by our parent star are of the same strength.
If the energy reaching the Earth each and every day is of the same intensity and strength, what causes the seasons that so many parts of our planet experience? Why are some parts of the year warm, some hot, and others very cold? If the Sun is continuously producing a constant, unchanging amount of heat, shouldn’t the seasons always be the same?
The changing seasons are caused by the movements of the Earth. There are two important movements that affect the Earth. The first is the rotation of the Earth around an invisible axis. It takes the Earth about 24 hours to finish one complete rotation. The second important movement that affects the Earth is its revolution around the Sun. One revolution takes 365 ¼ days, or one year. Acting together, these two movements create variations in temperature, weather, and in the seasons.