MOTIONS OF

EARTH, MOON

AND SUN

I. Motions

• movements

1. APPARENT MOTION

• Motion that an object appears to make

2. Daily motion and stars:

• Paths of all stars appear to be ______ or parts of a _____ called an ___.

• Rise in the _____ and set in the _____• Motion occurs at rate of ___________

(360 in 24 hours)• ______ remains stationary in the

center .

circularcircle arc

East West15o per hour

Polaris

**this apparent motion is because the Earth ROTATES!

Sta

r M

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t M

idd

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Lat

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3. Apparent Motions of Earth’s Moon:

• Same motion as the stars: rises in the ____ and sets in the _____.East West

4. Apparent motions of the Sun:

• Path from sunrise to sunset has the shape of an ___.

• Path changes in two ways throughout the seasons:1. Length2. Position in the sky

• Reaches highest point in sky at this time of day: __________.

arc

Solar Noon

• Can only be directly overhead (90) between ______ and ______.– Is the Sun ever directly overhead in

New York State?

23.5oN 23.5oS

NEVER!!

II. Models that Explain Apparent Celestial Motions:

1. Geocentric model:Earth doesn't move

and most celestial objects revolve around it

2. Heliocentric Model– _____ is at center of solar system– Earth ________ on its axis and

_________ around Sun.– Moon _______ on its

axis and _________around Earth.

Sunrotates

revolvesrotates

revolves

• Which of the two models do we believe today?

HELIOCENTRIC MODEL

• Moves with our galaxy, called the _________ as the Universe is _________.

• ____________ revolves around center of Milky Way (it takes ____ million yrs.)

• _______ on its axis and _______ around Sun in an orbit, whose shape is an ______.

IV. Actual Earth Motions

Milky WayexpandingSolar System

225Rotates revolves

ellipse

1. Rotation of Earth• Earth spins on its ______.• Its’ axis is tilted at _____.• Earth rotates at a rate of ____________.

axis23.5°

15° per hour

A. Evidence of Earth’s rotation

1. Foucault pendulum

A. Evidence of Earth’s rotation (ctd)

2. Coriolis effect– All objects moving at Earth’s surface are

____________________________________.– Deflection appears to the ______ in the Northern

Hemisphereright

deflected from a straight line path

2. Revolution of the Earth

• Revolves around sun in a slightly ________ orbit.

• Revolves at a rate of about ___________.– How many degrees in a circle?– How many days in a year?

elliptical

1o per day360o

365 days

360o

365 days

A. Evidence of Earth’s revolution around the Sun:

1. Different ___________ are visible during different times of the ____.

2. Apparent size of ____ changes as earth is ______ or ______ away

constellationsyear

Suncloser further

3. Earth Motions and Time

• Time is based on Earth’s _______ on its axis.

• ALL PLACES ON THE SAME LINE OF ____________ HAVE THE SAME TIME

• Time zones:–keep time the same for regions

rotation

LONGITUDE