how does the earth move?
DESCRIPTION
How does the Earth move?. 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 - PowerPoint PPT PresentationTRANSCRIPT
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 …