WHY DO WE HAVE DAY AND NIGHT??? October 5, 2012 - It’s Friday  WARM-Up (remember to date and write in your warm-up section) WHY DO WE HAVE DAY AND NIGHT??? Tests, Quizzes, etc are being returned.

1 The reason we have day and night is because the Earth rotates. 2 Rotate means to turn. The Earth rotating on its gives us day and night. axis http://www.youtube.com/watch?v=lkWyM-M8o0c 3 Earth’s axis is the imaginary line that goes through the center of the Earth.

This spinning around like a top is called rotation This spinning around like a top is called rotation. As it spins only one side faces the sun. Day begins when our part of the world turns to face the sun.

Night falls when our part of the Earth turns away from the sun Night falls when our part of the Earth turns away from the sun. The side facing away from the sun has nighttime.

DAY AND NIGHT 4 This rotation or spinning of Earth causes day and night. The Earth rotates on its axis. The axis is an imaginary line through its center. It rotates once every 24 hours causing day and night.

But guess what! Rotating isn’t the only way the Earth moves in space! 5 The Earth also revolves. Revolve – When one object moves around another object

The Earth has seasons because…? True or False? The Earth has seasons because…? The Earth moves closer to or farther from the Sun - it’s closer in the summer and farther in the winter.

False! 6 The Earth has seasons because its axis is tilted 23.5º and its revolves around the Sun. Have you ever notice how globes are always tilted?

7 One revolution around the sun equals 365.25 days.

8 Orbit - What about the word orbit? The path that an object follows as it revolves around another object.

Look at this diagram. Notice how the Earth is always tilted in the same direction. As the Earth __________, the part of Earth tilted toward the sun changes. revolves

During part of the year the North Pole tilts towards the sun During part of the year the North Pole tilts towards the sun. This season is ________. summer

When the North Pole is tilted toward the Sun, the Sun travels higher overhead in the sky. The Sun’s rays shine straighter down on that part of the Earth. It is summer in that part of the Earth. http://www.youtube.com/watch?v=ndlQNicOeso&feature=related

http://www.youtube.com/watch?v=ndlQNicOeso&feature=related

During another part of the year, the North Pole points away from the sun. This season is ______. winter

When the North Pole is tilted away from the Sun, the Sun stays lower in the sky. It is then winter in that part of the Earth.