Formulas

Motions and Their Effects Seasonal Change and Planetary Movement Seasons tilt of the Earth’s axis is 23.5 degrees This tilt causes seasonal changes The Winter Solstice December 21 or 22 North Pole in darkness for 24 hours South Pole has continual daylight Sun is at its lowest point Why do we have winter? hours of sunlight during the day North pole is tilted away from the sun Light rays are less direct Fewer Vernal Equinox (equal) 20 or 21 (Spring) Sun is directly over the equator Every part of the Earth experiences equal hours of day and night March Summer Solstice 20 or 21 South Pole in Darkness North Pole in Light Sun appears at its highest point June Why we have summer? hours are longer Sunlight is more direct Daylight Autumnal Equinox (equal) 22 or 23 (Fall) Equal hours of day and night Sun is directly over the equator September Questions many months apart are the solstices and the equinoxes? How is the vernal equinox similar to the autumnal equinox? How Questions are the differences between the summer and the winter solstices? Why do we have changes in seasons during the year? What Kepler Each planet moves in an elliptical orbit (stretched out circle) Planets speed up their orbit as they approach the Sun and slow down as they move away from it Questions was Kepler’s contribution to the understanding of planetary movement? TRANSPARENCIES What