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Earth’s Motions. ROTATION Earth spinning on its axis is called rotation. Earth spinning on its axis is called rotation. The “AXIS” is an imaginary line.

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Presentation on theme: "Earth’s Motions. ROTATION Earth spinning on its axis is called rotation. Earth spinning on its axis is called rotation. The “AXIS” is an imaginary line."— Presentation transcript:

1 Earth’s Motions

2 ROTATION Earth spinning on its axis is called rotation. Earth spinning on its axis is called rotation. The “AXIS” is an imaginary line passing through Earth’s center through the N. and S. Pole. The “AXIS” is an imaginary line passing through Earth’s center through the N. and S. Pole. The N. Pole points toward the star Polaris The N. Pole points toward the star Polaris The axis is tilted 23.5° {ch.2} The axis is tilted 23.5° {ch.2}axis

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4 DAY AND NIGHT Counterclockwise rotation (In N. Hemisphere)! Counterclockwise rotation (In N. Hemisphere)! Counterclockwise rotation Counterclockwise rotation Sun (Celestial Sphere; stars) rise in the East and set in the West. Sun (Celestial Sphere; stars) rise in the East and set in the West.Celestial SpherestarsCelestial Spherestars Time of Complete Rotation = ~24 hours Time of Complete Rotation = ~24 hours Speed at Equator = ~1 mile every 3 seconds Speed at Equator = ~1 mile every 3 seconds = 1,038 miles per hour = 1,038 miles per hour {Ch.1} {Ch.1}

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7 Oblate Spheroid Earth’s shape is considered to be the shape of an ellipsoid. Earth’s shape is considered to be the shape of an ellipsoid. Earth is wider than it is tall. Earth is wider than it is tall. Bulges at equator Bulges at equator Flattened at Poles. Flattened at Poles.

8 Solar vs. Sidereal Solar vs. Sidereal Solar Day (SYNODIC) Solar Day (SYNODIC) The time it takes Earth to rotate once with respect to the sun. (Suns Highest point in sky to the next highest point in sky). The time it takes Earth to rotate once with respect to the sun. (Suns Highest point in sky to the next highest point in sky). Time = 24 hours (mean time) Time = 24 hours (mean time) Sidereal Day Sidereal Day The time it takes the Earth to The time it takes the Earth to rotate once with respect to a reference star. One 360° Rotation One 360° Rotation Time = 23 hr. 56 min. Time = 23 hr. 56 min. 1-2: Globe rotates 360° - sidereal 1-3: Globe re-points to sun - synodic

9 Evidence of Rotation Foucault Foucault Pendulum Foucault The pendulum is suspended The pendulum is suspended above Earth’s Surface. The Earth spins underneath pendulum. The Earth spins underneath pendulum. Pendulum seems to change direction because rotation. (ch.8) Pendulum seems to change direction because rotation. (ch.8) seems

10 Precession The slow gyration of a spinning body. The slow gyration of a spinning body. Movement around a point or axis. Movement around a point or axis. The top does not fall over as long as it stays spinning. The top does not fall over as long as it stays spinning.

11 Earth’s Precession The Earth “WOBBLES” on its axis once every 26,000 years. The Earth “WOBBLES” on its axis once every 26,000 years.WOBBLES Earths precession Earths precession moves opposite to its rotation. Earth’s axis will not straighten Earth’s axis will not straighten due to its constant rotation.

12 Moving Toward VEGA

13 Revolution The movement of one object around another is called revolution. The movement of one object around another is called revolution.revolution Earth revolves around the sun in a path called its orbit (Counterclockwise direction). Earth revolves around the sun in a path called its orbit (Counterclockwise direction). 1 revolution = Days (LEAP YEAR?) 1 revolution = Days (LEAP YEAR?) Rate of Revolution = mph Rate of Revolution = mph


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