How does the Earth move?
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Transcript of How does the Earth move?
How does the Earth move?Objectives
EEn.1.1.2.C. Explain precession and its effect on the seasons
EEn.1.1.2.D. Explain nutation and its effect on the seasons.
Agenda
IN: Drawing Earth’s MotionTHROUGH: Precession/Nutation NotesOUT: Lesson ReflectionPRACTICE: Making Models
Notebook
Title: Precession and NutationDate: 2/28/13Pages:
Input: Left Top
• Draw a picture of the 2 main motions of the Earth (rotation and revolution).
So what does precession look like?
• http://www.youtube.com/watch?v=0qHjtp4cdCA
• The Earth’s axis is tilted at a 23.5º angle
• Precession: the change in direction of the Earth’s axis, but without any change in tilt-Like the wobbling motion of a spinning top
• 1 precessional cycle: approximately 26,000 years
• Minor effect on the seasons
The North Star
• Our North Star is currently Polaris
• Because of precession, in 13,000 years our North Star will be Vega
• Nutation: The wobbling/swaying motion during the precession of our axis.
• This causes a 1 degree change in the tilt of the Earth’s axis.
• No effect on the seasons
Output (Left Bottom)
• Reflect on what we’ve learned today by finishing the following sentences.
– Today, I learned …– I was surprised to find …– I wonder what would happen if…– The important thing about …