EARTH IN SPACE

The Earth in Space

Main Idea

Terms to Know • solar system • revolution

• axis

• rotation

• equinox

Places to Locate • Earth

• atmosphere

• sun

The earth has life because of the sun. Seasons change because of the way the earth tilts and revolves around the sun.

• winter

solstice

• summer solstice

Section Objectives

• Identify what makes up the solar system.

• Describe how Earth moves in space.

• Explain why Earth’s seasons change.

The Solar System

• The solar system is the sun, the Earth, the seven other planets (Pluto was demoted in August, 2006), and thousands of smaller bodies (dwarf planets, moons, comets, and asteroids).

• The planets and other bodies revolve

around the sun.

• A planet follows an elliptical path around

the sun. This is known as its orbit.

• There are two types of planets: 1. Solid and small like Earth 2. Resemble balls of gas like Jupiter.

Our solar system consists of:

Comets

Asteroids

Spheres covered with ice and dust that leave

trails of vapor as they race through space.

Large chunks of rocky material found in space.

What is Earth’s location in our solar system?

Earth is the third planet from the sun

Earth

Age: 4.5 billion years

Diameter: 7,926 miles

Temperature on surface: -89 °C to 57.7 °C

Distance from the Sun: 93 million miles

Satellite(s): the Moon (also known as "Luna" or "Selene")

The name of Earth comes from the Anglo-Saxon word Erda, which means ground, soil

and earth.

Origins

When it was formed 4.5 billion years ago, the Earth looked very different to how it does

now. The surface was littered with active volcanoes and, with no ozone layer, the

atmosphere gave no protection from the Sun.

As the Earth grew in size, its increasing gravitational field pulled more material towards

it. This caused more asteroids to hit the Earth with greater force, which meant its surface

heated up and began to melt. This melting gave Earth its layered structure.

Structure

The innermost layer, or core, is under such intense pressure that it

has remained partly solid at the centre. It is made up of nickel and

iron and has an estimated temperature of 4,000 Kelvin or 3,726

degrees Celsius. Beyond the core is the mantle, which is the largest single part of the planet. It is semi-solid and accounts for 82%

of the Earth's volume and 67% of its mass. The mantle is divided into three separate regions - the lower mantle, which is 2,290 km

thick, the transition zone and the upper mantle, which is 630 km thick. Above the mantle is the surface of the Earth, known as the

crust. The crust varies in thickness, from as little as 7 km in some parts of the ocean, to 70 km under the mountain ranges.

Atmosphere

The Earth is surrounded by a blanket of gases, known as the atmosphere. It provides us with the air we breathe and insulates us

from drastic changes in temperature. It also protects us from harmful ultraviolet radiation from the Sun. The atmosphere extends for

more than 300 miles above the Earth but is thickest in the 10 miles closest to its surface. As you travel further from the Earth it thins

out and merges with space.

The biosphere

Considering the size of the Earth, life is confined to only a very small area.

Almost all living things are found in a zone called the "biosphere", which runs from 200 m below the surface of the oceans to 30 m

above it. Of course, many humans live above this height, but even for us the options are limited. The higher you go, the more you

will experience altitude sickness as the atmosphere thins and your body struggles to get enough oxygen from the air. Mountaineers

start to use breathing apparatus when they go above about 7,000 m.

What is unique about earth?

It is the only planet that supports life!

Can You?

Describe the solar system and Earth’s location in it.

Earth – Sun Relationships

Axis – An imaginary line that runs through the center of earth

Earth's Tilt

The tilt of the Earth on its axis affects the amount of solar energy that different places receive during the year.Because of this tilt more of the earth’s surface receives direct rays from the sun.

The Earth's polar axis tilts at an angle of 23 ½ ° with its orbital plane around the sun. This

inclination is responsible for more of the Earth receiving direct rays from the Sun and thus, the

climate changes and the seasons experienced on Earth.

If the Earth had no tilt all places on earth would receive the same amount of solar

energy year round…

How different would our world be?

The spinning of the Earth on

it’s axis.

This spinning helps to “even

out” heat from the sun.

•Earth rotates around its own axis once every 24 hours (1 day).

•This is the cause of day and night.

If we divide 360° by 24, we get 15°.

In other words, it takes the Earth 1 hour to turn through 15°.

•Earth rotates from West to East

Rotation –

Remember!!!

Does the Sun "Rise"?

One side of the Earth

would receive no sunlight

How different would our world be?

What if the Earth did not rotate?

One side of the Earth would

receive sunlight all the time

Revolution - The earth’s complete orbit around the sun.

•This revolution takes 365¼ days, which is why we

have a leap year once every four years.

What is the speed of earth’s revolution?

66,000 mph (1,100 miles per minute)

If the Earth did not revolve around the sun

Can you imagine if it were always summer

Or always winter

No spring or fall

Our earth would be a much different place

The shape of the Earth directly

affects the amount of solar

radiation received during

certain segments of its

revolution around the sun.

Equatorial regions receive

more direct rays of the sun,

thus more solar radiation.

Moving farther south or north of

the equator will change the

angle at which the rays strike

the Earth, thus decreasing the

amount of solar radiation

received at that latitude.

Earth makes two motions in space.

• It spins on an imaginary axis that runs through

the center of Earth between the North and South

Poles.

• It takes 24 hours for Earth to complete one

rotation on this axis.

• What is our speed of rotation? About 775 mph

•It revolves around the sun on its orbit

•It takes 365 ¼ days (1 year) to complete 1 revolution

Can you?

Assess the impact of tilt, rotation, and revolution on the amount of solar

energy the earth receives.

Solar Energy and Latitude

Sun angle diagram

The angle of Sun’s

rays determine heat

The amount of solar energy a place receives relates to the angle at which the

Sun’s rays strike the earth.

Tropics (Red) – warm, low latitude areas near the equator

Middle latitudes (Green) – areas of latitude between the tropics and polar regions

High latitudes (White) – cold, high latitude areas near the poles

Earth’s tilt ensures that more of the earth’s surface receives direct rays from the sun.

Earth’s Temperature Change

Which latitudes receive the most solar energy throughout the year?

Can you tell when its winter in the northern hemisphere?

We refer to times of greater and lesser heat

as the seasons.

The four general seasons are: winter, spring,

summer, and fall.

The Sun’s energy is stronger during the

summer. Daytime lasts longer.

In the winter, daytime is shorter, and the

Sun’s energy is weaker.

SEASONS

The tilt of the Earth’s axis causes the Northern and Southern Hemispheres to

have opposite seasons at the same time of the year.

• The day on which the Northern Hemisphere receives

the most hours of sunlight is the summer solstice.

• On this day, the sun is directly over the Tropic of

Cancer (23½ degrees north).

• The summer solstice falls on June 21/22

Summer solstice

The Sun and the Seasons

Summer solstice diagram

summer

solstice

Summer sunlight

Midnight sun

Land of the Midnight Sun

During the summer and winter our poles receive:

24 hours of daylight (Summer) or 24 hours of darkness (Winter)

Winter solstice

The Sun and the Seasons

• The day on which the Northern

Hemisphere receives the least sunlight is

the winter solstice.

• On this day, the sun is directly over the

Tropic of Capricorn (23½ degrees south).

• The winter solstice falls on December 21/22

Winter solstice diagram

winter

solstice

Winter daylight

Equinoxes

The Sun and the Seasons (cont.)

• The two days each year on which the sun

is directly over the Equator are known as

the equinoxes.

• Both hemispheres receive the same

amount of sunlight on these days.

• The autumnal equinox falls on September

22/23

• The vernal (spring) equinox falls on March 22/23

Equinox diagram

equinox

Summary diagram

equinox

Can you?

Discuss the impact of tilt and revolution on the seasons.

The Earth System

Interaction of Earth’s different parts

We are in a continuous

cycle if interactions with

our planet.

Earth’s Four Spheres

•Earth is surrounded by a layer of air called the atmosphere.

Atmosphere

The atmosphere consists of a mixture of gases composed primarily of nitrogen,

oxygen, carbon dioxide, and water vapor retained by the Earth's gravity.

Atmosphere diagram

It extends some 500 km

above the surface of the

Earth and the lower level

(troposphere) constitutes

the climate system that

maintains the conditions

suitable for life on the

planet's surface. Our

outer atmosphere, the

stratosphere, contains

the ozone layer that

protects life on the planet

by filtering harmful

ultraviolet radiation

from the Sun.

Hydrosphere

All of Earth’s water

Water covers

about 70% of

Earth’s surface.

Lithosphere

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The Lithosphere is the solid crust of the planet, it forms Earth’s continents, islands,

and ocean floors. It includes all of Earth's rocks and soil.

Eruption of Mount St. Helens volcano, 1980. The volcano, located in the state of Washington, rose to a height of

9,677 feet and was a perfect cone shape before the eruption. The explosion caused the breaking away of the

uppermost 1,300 feet, and resulted in the largest landslide in recorded history.

Our land recycles itself through

its internal processes

Biosphere

The part of Earth

that includes all life

forms (plants and

animals); overlaps the

other three spheres

(atmosphere,

lithosphere, and

hydrosphere.)

The four spheres of Earth work together to our environment or surroundings.

Earth’s Environment – Earth’s surroundings including the four spheres and

all biological, chemical, and physical conditions that interact and affect life.

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