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EARTH IN SPACE
The Earth in Space
Main Idea
The earth has life because of the sun. Seasons
change because of the way the earth tilts and
revolves around the sun.
Terms to Know
• solar system
• atmosphere
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•
•
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Places to Locate
• Earth
• sun
revolution
axis
rotation
equinox
• 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
Spheres covered with ice and dust that leave
trails of vapor as they race through space.
Asteroids
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 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.
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.
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?
Rotation –
The spinning of the Earth on
it’s axis.
This spinning helps to “even
out” heat from the sun.
Remember!!!
•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
Does the Sun "Rise"?
What if the Earth did not rotate?
One side of the Earth
would receive no sunlight
One side of the Earth would
receive sunlight all the time
How different would our world be?
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
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?
SEASONS
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.
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 Sun and the Seasons
• 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
summer
solstice
Land of the Midnight Sun
During the summer and winter our poles receive:
24 hours of daylight (Summer) or 24 hours of darkness (Winter)
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
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
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
Atmosphere
•Earth is surrounded by a layer of air called the 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.
Our land recycles itself through
its internal processes
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.
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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