EARTH, MOON, & SUNEARTH, MOON, & SUN

Earth’s movement in space.Earth’s movement in space.

Earth rotates on it’s imaginary Earth rotates on it’s imaginary axis.axis.

This imaginary line (This imaginary line (axisaxis) passes through ) passes through the Earth at it’s North and South poles. the Earth at it’s North and South poles.

Earth’s rotation causes day and Earth’s rotation causes day and night.night.

As the Earth rotates As the Earth rotates toward the east, the toward the east, the sun appears to sun appears to move toward the move toward the west. (The sun rises west. (The sun rises in the east and sets in the east and sets in the west.)in the west.)

To help remember Earth’s rotational To help remember Earth’s rotational direction, think about New York.direction, think about New York.

The Eastern Time Zone (New York) is one The Eastern Time Zone (New York) is one hour ahead of us (Central Time Zone). hour ahead of us (Central Time Zone).

                                                                                                                                                    

                                                    

                                                                                                                                                    

                                                    

How long does it take the Earth to How long does it take the Earth to complete a rotation?complete a rotation?

24 hours24 hoursAs you know, each 24 hour As you know, each 24 hour

cycle is called a day.cycle is called a day.

While rotating on its axis, Earth also While rotating on its axis, Earth also revolves around the sun.revolves around the sun.

The Earth is rotating on it’s axis The Earth is rotating on it’s axis and at the same time it is revolving and at the same time it is revolving

(revolution) around the sun.(revolution) around the sun.

The word rotation is shorter than the word The word rotation is shorter than the word revolution.revolution.

Rotation = 24 hours/ one dayRotation = 24 hours/ one day

Revolution = 365.26 days/ one yearRevolution = 365.26 days/ one year

D.O.S.

1. What do we call Earth’s movement on it’s axis?

2. How long does this cycle take to complete?

3. What do we call Earth’s movement around the sun?

4. How long does this cycle take to complete?

The SeasonsThe SeasonsMost places on Earth (outside the tropics and Most places on Earth (outside the tropics and

polar regions) have 4 distinct seasons: winter, polar regions) have 4 distinct seasons: winter, spring, summer, and autumn (fall).spring, summer, and autumn (fall).

Why are temperatures warmer in the tropics and Why are temperatures warmer in the tropics and colder in the polar regions?colder in the polar regions?

WhatWhat causescauses thethe seasonsseasons onon EarthEarth??

There are two main reasons.There are two main reasons.

The tilt of Earth’s axis and Earth revolving The tilt of Earth’s axis and Earth revolving around the sun.around the sun.

Earth’s axis is tilted at an angle of 23.5 Earth’s axis is tilted at an angle of 23.5 degrees as the Earth revolves around the degrees as the Earth revolves around the sun.sun.

As Earth revolves around the As Earth revolves around the sun, the north end of its axis is sun, the north end of its axis is tilted away from the sun for part tilted away from the sun for part of the year and toward the sun of the year and toward the sun

for part of the year.for part of the year.

During Kentucky’s winter, the southern hemisphere receives the majority of the solar radiation because the south pole is

tilted toward the sun. The day in which the daylight hours are the shortest in the

northern hemisphere is December 22, the Winter Solstice (sun is farthest south of the

equator).

Winter

Six months later, on June 22, the earth has completed one half of its orbit with the

northern hemisphere receiving the majority of the radiation. This is called the Summer

Solstice, the sun is farthest north of the equator. Notice the north pole is tilted toward

the sun.

Summer

Twice a year, March 21 and September 23, both hemispheres receive the same

amount of radiation. The days are called the equinox meaning equal

night. Both hemispheres have 12 hours of daylight and darkness.

Spring

Autumn

1.1. Why do some parts of Earth not Why do some parts of Earth not have seasonal changes like we have seasonal changes like we do in Kentucky?do in Kentucky?

2.2. What causes the four seasons What causes the four seasons that we experience?that we experience?

3.3. What is the degree measure of What is the degree measure of Earth’s axis?Earth’s axis?

Gravity & MotionGravity & Motion

What is gravity?What is gravity?

The force that pulls all objects The force that pulls all objects toward each other.toward each other.

Does the Earth, moon, and sun Does the Earth, moon, and sun have gravity?have gravity?

If the sun and Earth are constantly If the sun and Earth are constantly pulling on each other because of pulling on each other because of gravity, what keeps the Earth gravity, what keeps the Earth from falling into the sun? What from falling into the sun? What keeps the moon from crashing keeps the moon from crashing into the Earth?into the Earth?

Think about The Law of Inertia.Think about The Law of Inertia.

D.O.S. D.O.S.

What phase was yesterday’s/ last night’s What phase was yesterday’s/ last night’s moon?moon?

List the moon phases in order starting with List the moon phases in order starting with a new moon. a new moon.

Moon’s Rotation & RevolutionMoon’s Rotation & RevolutionThe moon takes 27.3 days to complete one rotation and one The moon takes 27.3 days to complete one rotation and one

revolution.revolution.

The moon phases takes 29.5 days to complete. The phases The moon phases takes 29.5 days to complete. The phases start with a New Moon (no visible moon) and then moves start with a New Moon (no visible moon) and then moves into a First Quarter Moon. The next phase is a Full Moon. into a First Quarter Moon. The next phase is a Full Moon. When the moon moves from a New Moon to a Full Moon When the moon moves from a New Moon to a Full Moon it waxes (what you see gets larger over several nights). it waxes (what you see gets larger over several nights).

After the moon completes it’s Full Moon After the moon completes it’s Full Moon phase it moves to the Third (Last) Quarter phase it moves to the Third (Last) Quarter phase and then back into the New Moon phase and then back into the New Moon

phase. What we see over several nights is phase. What we see over several nights is the visible moon getting smaller. This is the visible moon getting smaller. This is

called waning.called waning.

Eclipses and TidesEclipses and Tides

Solar EclipseSolar Eclipse

A solar eclipse occurs when the Moon passes in front

of the Sun and obscures it totally or partially. This configuration can only exist at New

Moon, when Sun, Moon and Earth are on a single line with the Moon in the

middle.

Lunar EclipseLunar Eclipse

The differenceThe difference

A Solar eclipse only occurs when the A Solar eclipse only occurs when the moon is in a straight line between the sun moon is in a straight line between the sun and Earth during the New Moon phase.and Earth during the New Moon phase.

A Lunar eclipse only occurs when Earth is A Lunar eclipse only occurs when Earth is between the sun and the moon during the between the sun and the moon during the Full Moon phase. The Earth blocks the Full Moon phase. The Earth blocks the sunlight normally reflected by the Moon.sunlight normally reflected by the Moon.

TidesTidesBulging is produced on the Earth`s crust and its oceans. The Moon produces two tidal bulges on the Earth through the effects of gravitational pull. The height of the tidal bulges is controlled by the Moon's gravitational force and the Earth's own gravity pulling the water back.

At the location on the Earth closest to the Moon, seawater is drawn toward the Moon. On the opposite side of the Earth, another tidal bulge is produced away from the Moon where the force of its gravity is weakest.

When the Sun and the Moon are at 90º to the Earth (during first and last quarter moons), the gravitational pull of the Sun and Moon are competing. At these times, high tides do not rise very high and low tides do not fall very much. These are known as neap tides.

Earth`s tides are also affected by the Sun as the Earth orbits around it. When the Earth, Moon and Sun are in line twice a month at new and full moons, the gravitational pull on the Earth is increased, and high tides are higher than at any other times. Conversely, low tides are at their lowest. These are called spring tides.