Students will be able to Define and distinguish
Students will be able to: • Define and distinguish between rotation and revolution • Understand that the day is based on Earth’s period of rotation on its axis • Understand that the year is based on Earth’s period of revolution around the sun ASTRONOMY Lesson 2 – Our Internal Clock
Measuring Time • Time is measured using cyclic motions of Earth • The day is based on 1 Rotation (spin) • The Year is based on 1 Revolution (orbit)
Rotation • Earth rotates 360⁰ in 24 hrs • 15⁰/hr • The rotation is from West to East
Draw this M Terminator S NP R N • Label the North pole • Label the Terminator • Draw arrows for sunlight • Draw an arrow showing the direction of rotation • Put an “N” where it would be noon • Put an “M” where it would be midnight • Put an “R” where the sun would be rising • Put an “S” where the sun would be setting
Revolution • Earth orbits the sun once every 365. 26 days (year) • That’s 360⁰ in 365 days Or • About 1⁰ /day
Open your ESRT to pg 15 • Can you find earth’s rotation and revolution periods? • Why is the rotation different from what we learned?
• From position 1 to position 2 earth rotates 360⁰ • Because it moved along in its orbit, it is no longer facing the sun. It takes the extra 4 minutes to face the sun again
Apply what you learned • Scientists have calculated that the earth’s rate of rotation is slowing down. What effect will this have on humans?
Time humor
- Slides: 9