Reasons for the Seasons

• The earth revolves around the sun once every 365 ¼ days.

• The revolution around the sun is called the orbit.

• The Earth rotates on its axis once every 24 hours.

• Earth is tilted on a 23 ½ degree rotational axis.• Earth rotates counter- clockwise revolves

counter-clockwise around the sun.

Day and Night

• Light can only travel in a straight line. It cannot travel around the curvature of the Earth to illuminate the other side.

• The Earth’s own shadow makes the night side of the Earth dark.

• One-half of the Earth is always lit, while the other side is in darkness.

• The line between the lit portion of the Earth and the dark portion is called the Terminator.

The moon rotates on it’s axis, and revolves around the Earth once every 27.3 days