The Earth-Moon The Earth-Moon RelationshipRelationship

What is revolution?What is revolution?

- When an object moves around another object- When an object moves around another object What is the revolution of the Earth?What is the revolution of the Earth?

-365 days-365 days

What is a rotation?What is a rotation?- When an object moves around it’s own When an object moves around it’s own

axis.axis.o What is the rotation of the Earth?What is the rotation of the Earth?

-24 hours-24 hours

Just the Facts….Just the Facts….EarthEarth Diameter= 12,756kmDiameter= 12,756km

RotationRotation= 24 hours= 24 hours

Revolution around the Revolution around the sunsun =365 days =365 days

MoonMoon Diameter= 3,476kmDiameter= 3,476km

RotationRotation= About 27 days = About 27 days and 8 hoursand 8 hours

Revolution around EarthRevolution around Earth= = 27 days and 8 hours27 days and 8 hours

Average Distance from Average Distance from Earth 240,000 milesEarth 240,000 miles

The Moon does not make any The Moon does not make any light of its own, but just light of its own, but just

reflects sunlight down to earth.reflects sunlight down to earth.

Why do we only see one side of the Why do we only see one side of the moon?moon?

……because the period of rotation for the because the period of rotation for the moon is the same as its period of revolution.moon is the same as its period of revolution.

Try it…….Try it…….- Mark a ball (moon) with an “x” on it. This Mark a ball (moon) with an “x” on it. This

represents the near side of the moon.represents the near side of the moon.- Hold the ball out in front of you (sun) and Hold the ball out in front of you (sun) and

rotate with the “moon” a complete circle.rotate with the “moon” a complete circle.- Notice-the sun and moon both made a Notice-the sun and moon both made a

complete rotationcomplete rotation

Now, rotate around with the “x” facing the Now, rotate around with the “x” facing the same direction the entire time. same direction the entire time.

If this were the case, the moon would not If this were the case, the moon would not be rotating, and we would see the far side be rotating, and we would see the far side of the moon!of the moon!

Phases of the MoonPhases of the Moon

Within a month, the moon changes from a Within a month, the moon changes from a fully lit circle to a thin crescent and then fully lit circle to a thin crescent and then back to a circleback to a circle

Result of the changing position with Result of the changing position with respect to the Earth and the sun.respect to the Earth and the sun.

The different appearances of the moon The different appearances of the moon due to its changing position are called due to its changing position are called phasesphases

Waxing vs. WaningWaxing vs. Waning

WaxingWaxing-when the sunlit fraction we see -when the sunlit fraction we see

from the Earth is getting from the Earth is getting LLAARRGGEERR..

WaningWaning- when the sunlit fraction we see - when the sunlit fraction we see

is getting is getting SSMMAALLLLEER.R.

Like Like ClockClockwork…work…

EARTHEARTH

12

3

6

9 SUNM

1. New Moon

M

2. Waxing Crescent

M

MM

M

M

M

M

3. First Quarter Moon

4. Waxing Gibbous

5. Full Moon

6. Waning Gibbous

7. Last Quarter8. Waning Crescent

Phases of the Moon…Phases of the Moon…

Let’s Try…Let’s Try…

You are the Earth. Hold the pencil with You are the Earth. Hold the pencil with the Styrofoam ball (moon).the Styrofoam ball (moon).

Have another friend hold the light (sun) at Have another friend hold the light (sun) at 3:00.3:00.

Rotate your body with the moon and Rotate your body with the moon and observe the various phases of the moon.observe the various phases of the moon.

What’s an Eclipse?What’s an Eclipse?

Occurs when the shadow of one celestial body Occurs when the shadow of one celestial body falls on another. falls on another.

Lunar Eclipse-Lunar Eclipse- Earth Earth comes comes betweenbetween the the sun sun and the and the moon moon and the shadow of the Earth and the shadow of the Earth falls on the moon. This happens every 6 falls on the moon. This happens every 6 months.months.

October 27,2004 Lunar EclipseOctober 27,2004 Lunar Eclipse

Solar Eclipse- Happens when the Solar Eclipse- Happens when the moonmoon comes comes betweenbetween the the EarthEarth and the and the sunsun and the shadow and the shadow of the moon falls on part of the Earth.of the moon falls on part of the Earth.

Movie of Solar EclipsesMovie of Solar Eclipses

TidesTides The effect of The effect of

gravity between the gravity between the sun, moon and sun, moon and earth causes earth causes tidestides..

Tides are a result Tides are a result of the moon pulling of the moon pulling the water toward it.the water toward it.

When the moon is When the moon is on on your sideyour side of the of the Earth, you have a Earth, you have a high tide.high tide.

When the moon is When the moon is on the on the opposite opposite sideside of Earth, you of Earth, you have a have a low tidelow tide..