Earth carries out 2 motions at the same time, rotation and revolution. Rotation means to spin about an axis whereas revolve means to orbit around a body (in our case it is the Sun). Rotation gives us day and night and 1 rotation occurs every 24 hours. Revolution gives us seasons and one complete revolution takes 365.25 days. Every 4 years, the .25 day adds to a whole day, so we stick it onto the end of February and call it leap year.
We cannot feel the Earth spinning. Evidence for Earth's rotation is the Coriolis Effect and Focault's Pendulum.
Virtual Notes:
Manipulate the simulator below to make observations about the path of the sun or length of shadow based on the time of day or year. Set the simulator to June 21 to see the sun at its most South part in the sky (getting the highest), September 23 to see the sun rise due east and set due west, December 21 to see the sun peak at its lowest point in the sky, and March 21 to see the sun rise due east and set due west.
Position of Sun at sunrise and sunset throughout the year:
Seasons and Ecliptic Simulator: Pay special attention to the red latitude line (equator) and the line directly above (tropic of cancer) and below (tropic of capricorn). These are the only places on Earth that receive true overhead sun at noon at certain times of the year. Insolation is a fancy word for incoming solar radiation. The angle of insolation is the angle that the sun makes with the horizon, in the Northern Hemisphere, it is greater in the summer and less in the winter. The duration of insolation is how long the sun is in the sky (how long the day is).
Polar Projections:
The Earth can look very different when viewed from the poles, but we can still recognize the seasons. In New York in summer, we get close to 15 hours of light and 9 hours of darkness. All along the Northern Hemisphere, locations get more hours of light than dark and it gets more extreme as you go north. The North Pole gets all light and never rotate through darkness. Adjust the simulator to June 21 and observe the day and night line. The North Pole stays in light for all 24 hours of rotation. Winter in the Northern Hemisphere is the opposite. New York gets close to 9 hours of light and 15 hours of dark and once again, the more north you go, the more pronounced the effect. The North Pole remains in darkness for the entire 24 hours of rotation and never passes into the light. Adjust the simulator to December 21 and observe the day and night line. The North Pole stays in dark for all 24 hours of rotation. Spring and Fall have equal hours of light and dark. Adjust the simulator to March 21 and September 23 and observe the day and night line. The North Pole and everywhere else on Earth receives 12 hours of light and 12 hours of dark.