You will be able to… •Describe the movements of Earth known as rotation and

revolution.

•Explain how the moon goes through phases.

•Explain how eclipses occur.

22.2 The Earth-Moon-Sun System

Motions of Earth

22.2 The Earth–Moon–Sun System

The two main motions of Earth are

rotation and revolution.

22.2 Motions of Earth

Rotation • Rotation is the turning, or spinning, of a body on its

axis.

• Earth’s axis is the imaginary line that passes thru

the center and connects the north and south pole.

• 1 complete rotation of Earth equals 1 Day = 24 hrs.

22.2 Motions of Earth

Revolution • The movement of one object around another

in space is called revolution.

• It takes Earth 365.25 days to make one

complete orbit or revolution around the sun.

http://www.youtube.

com/watch?v=8bAfi

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elated

Seasons

• As earth revolves around the sun, we experience different seasons. – Seasons are caused by the

23.5° tilt of Earth’s axis.

• During the summer in the Northern Hemisphere, the north pole is tilted towards the sun.

• During the winter in the N. Hemisphere, the north pole is tilted away from the sun.

• Earth is closer to the sun during our winter

and farther away during our summer.

22.2 Lunar Cycle

• Lunar phases are a result of the motion of the

moon and the sunlight that is reflected from its

surface.

•The gradual change in the appearance of

the moon is known as the lunar cycle.

Phases of the Moon

• New moon – when the moon is between earth and the sun

Phases of the Moon

• Full moon – When earth is between the moon and the sun.

Phases of the Moon

• Crescent – More darkness than

light on the moon.

Phases of the Moon

• Quarter (Half) – When half the moon

is dark and half is light.

Phases of the Moon

• Gibbous – When more of the

moon is light than dark.

Adding to the Phases of the Moon

• Waxing – when the

size of the visible

portion of the moon

increases.

• Waning – The portion

of the moon visible

from earth decreases.

22.2 Two Types of Eclipses

Solar eclipses occur when the moon moves

in a line directly between Earth and the sun,

casting a shadow on Earth.

• S = Sun

• o = moon

Solar Eclipse • Tip: Lasts no longer than 7 ½ minutes.

• 2 to 5 per year.

• Solar eclipse can only been seen by

people along the shadows path

• http://csep10.phys.utk.edu/astr161/lect/time/eclipse_anim.html

• http://csep10.phys.utk.edu/astr161/lect/time/eclips94.mpg

• Lunar eclipses occur when the moon passes

through Earth’s shadow.

During a new-moon or full-moon phase,

the moon’s orbit must cross the plane of

the ecliptic for an eclipse to take place.

Can occur at most 3 times a year

Lunar eclipse can be seen by everyone on the

dark (night) side of earth.

Lunar Eclipse • Lasts no longer than 3 hours and 40 minutes.

• During a total lunar eclipse, the moon doesn't simply fade to

black. In fact, it often takes on a reddish hue, ranging from

peach to crimson. This has to do with the way the atmosphere

scatters sunlight.