Ch. 17 Ch. 17 Lesson 1Lesson 1How does How does

Earth move?Earth move?

clues that Earth clues that Earth is moving:is moving:

1.1. Sun & stars seem to Sun & stars seem to move across skymove across sky

2.2. change of seasonschange of seasons

Why can’t you feel Why can’t you feel Earth’s movement?Earth’s movement?

Earth moves Earth moves steadily & smoothlysteadily & smoothly

axisaxisimaginary line that runs imaginary line that runs thru. North Polethru. North Pole Earth’s Earth’s ctr.ctr. South Pole South Pole

tilt of Earth’s axistilt of Earth’s axis

causes causes seasons seasons to changeto change

The Earth's Tilt on Its Axis and the Seasons [02:15]

rotationrotationspinning spinning motion of motion of Earth on Earth on its axisits axis

rotrotaationtionxxiiss

rotationrotation23 hours & 56 min. 23 hours & 56 min.

rotationrotationcauses day & nightcauses day & nightEarth rotates from Earth rotates from westwest east east

Earth's rotation animation

revolutionrevolutionmovement of one movement of one object around anotherobject around another

Rotation-Revolution animation

Rotation & RevolutionRotation & Revolution

The Movement of the Earth [04:18]

orbitorbitpath Earth takes as it path Earth takes as it revolves around Sunrevolves around Sun

Force of gravity Force of gravity keeps Earth in its keeps Earth in its orbit.orbit.

ellipse (elliptical)ellipse (elliptical)Shape of Earth’s orbitShape of Earth’s orbitStretched out circle Stretched out circle (oval)(oval)

Rotation and Revolution quizRotation and Revolution quiz

1. What is an axis? 1. What is an axis? 2. The Earth _____around the Sun.2. The Earth _____around the Sun.3. The Earth _____on its axis.3. The Earth _____on its axis.4. Does the Earth rotate and 4. Does the Earth rotate and revolve at the same time?revolve at the same time? Explain your answer.Explain your answer.5. How would Earth be affected if 5. How would Earth be affected if its axis weren’t tilted?its axis weren’t tilted?