The Seasons Day Night Cycle

Rotation is the spin of an object about its axis. – The Earth rotates once a day (once every 24 hours). Revolution is the orbit of one object around another. – The Earth revolves around the Sun every days.

The axis around which the Earth rotates is tilted by 23.5 degrees with respect to the ecliptic.

Many people carry the misconception that the seasons are due to the distance of the Earth from the Sun. However, consider the following facts: – The Earth’s orbit around the Sun is nearly a perfect circle. The Earth is slightly closer to the Sun in January and farther from the Sun in July. – While it is winter in the Northern hemisphere it is summer in the Southern hemisphere. If the seasons were due to our distance from the Sun both hemispheres would have the same seasons at the same time.

In fact, the seasons are due to the tilt of the Earth’s axis. Consider what happens on June 21 when the northern hemisphere of the Earth is tilted toward the Sun: The sunlight strikes the ground more vertically than in December. The light is spread out over less ground and heats the ground better. The Sun is above the horizon for a longer period of time.