What Causes Seasons on Earth
It's a hot time for some cool science.
Rotation and Revolution <br></br> What is the difference between rotation and revolution? This video explains how rotation and revolution affect days, years and seasons. <br></br> What Causes Earth's Seasons? <br></br> Earth's seasons are caused by the earth's movement around its axis. Instead of going straight up and down, earth’s axis tilts 23.5 degrees. Do you see why the earth’s movement cause seasons throughout the year? Let find out. <br></br> Here is the energy of the sun, notice it heats the lower half of earth, called the southern hemisphere, most directly. The sun's energy heats the northern hemisphere too, but look at how the northern hemisphere is pointed away from the sun -- also the light's heat adds an angle to cause the light to be spread over greater area. So this part is revolution, it receives less of the sun's energy. When more of the sun's energy heats the southern hemisphere, it causes the temperature to go up. In the summer time the days are longer. With less of the sun's energy heating the northern hemisphere, it gets colder like winter time. In the winter, there are longer nights and shorter days. Let see how seasons change as earth revolves. <br></br> So seasons change because the tilt of earth's axis causes the earth's hemisphere to receive different amounts of the sun's energy. <br></br> Astronomy: <br></br> The study of the moon, stars, and other objects in space. The imaginary line that passes through the earth’s center and the north and south poles. 23.5° angle tilt. <br></br> What is Rotation? <br></br> Earth’s rotation or spinning on its axis (23.5 degrees), which causes day or night and time for one rotation is about 24 hours. It spins counter clockwise. <br></br> What is revolution? <br></br> The earth revolves in an oval shape called an ellipse. A revolution or orbit is the time it takes for the earth to make one complete revolution around the sun. Time for one revolution = 365.25 days or one year and the speed of earth’s revolution is 68,000 miles per hour. Orbit: earth’s path as it revolves around the sun. <br></br> The Seasons: Caused by: 1. Revolution of the earth around the sun and 2. The unchanging tilt of the earth’s axis. When the North Pole tilts toward the sun, the Northern Hemisphere is experiencing summer. When the South Pole tilts toward the sun, the Northern Hemisphere is experiencing winter. <br></br> Summer: Sun is more overhead and “direct” which causes more of a direct (strong) path for radiation. Shadows are shorter. <br></br> Winter: Sun is more slanted and “indirect” which causes a less direct (weaker) path for radiation. Shadows are longer. <br></br> Conclusion: <br></br> Earth’s rotation or spinning on its axis (23.5 degrees) causes day or night. The time for one rotation is about 24 hours and it spins counterclockwise. <br></br> Thanks for watching!