 What features does the Earth possess that distinguishes it from other planets?  How does Earth’s axial tilt cause seasons?  What causes the daily apparent motion of the sun and moon?

 The Earth is the third planet from our star, the Sun.

 The Earth has one natural satellite- The Moon.

 The Earth is the only planet with water in all three states - liquid, solid and gas.  The Earth’s atmosphere is rich in Oxygen and Nitrogen

 1 day = 1 turning of the Earth on its axis (rotation).  This happens once every 24 hours.

 The sun, stars, and moon do NOT move across the sky, this is apparent motion.  The Earth’s rotation causes us to see them move from place to place.

 The Earth is tilted on its axis 23.5 degrees.  What effect might this have on different places on the globe? (ask your partner)

 Imagine the Earth’s tilt and its movement around the sun. Which direction is the north pole tilted in winter?  Visualization Visualization

 The path of the Earth around the sun is called its revolution.  This takes 365 days- (1 year)

 For the Northern Hemisphere, this occurs on the day the North Pole is tilted most towards the sun.  The sun is directly overhead the Tropic of Cancer (23.5° N latitude).  This is the longest day of the year (has the longest amount of daylight).

 For the Southern Hemisphere, this occurs on the day the South Pole is tilted most towards the sun.  The sun is directly overhead the Tropic of Capricorn (23.5 S ° latitude).  This is the shortest day of the year (has the shortest amount of daylight).

 On the days that the North and South Poles are parallel with the sun and the equator is getting direct light, we have an equinox.  On those days, day and night are equal length.

 There is an equinox around Sept. 23 – marking the first day of Autumn (autumnal equinox.)  There is another equinox around March 21 – marking the first day of Spring (vernal equinox.)

 Since the sun shines more directly on different areas of the Earth, it creates seasons.

 In two words, why do we have seasons?

 Earth’s Tilt  Seasons from space video Seasons from space  Visualization of seasons Visualization of seasons