Download The Solar System

The Solar System
8th Grade Science
The Solar System Evolves
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The solar system is the
sun, the planets, and all
the other objects that
revolve around the sun.
The nebular theory states
that our solar system
began as a huge cloud of
dust and gas, which later
condensed to form the sun
and its nine planets.
The Sun Forms First
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About 5 billion years ago,
a star exploded in a huge
supernova.
The nebula that was
home to the star begins to
collapse and pull matter
toward the center.
At the center, a protosun
forms.
The Planets Form
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Gases and other matter
surrounding the newly formed
sun continue to spin around it.
Gravity causes the matter to
gather into small clumps, then
into larger clumps called
protoplanets.
As the newly formed planets
began to cool, smaller clumps
of matter formed around them.
Giving the planets their moons.
Motions of the Planets
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In the second century B.C.
Ptolemy proposed a theory
that the Earth was at the
center of the universe; and
that all objects moved in
perfectly circular orbits.
Nicolaus Copernicus then
proposed a theory that the
Earth and the other planets
actually revolved around
the sun.
Motions of the Planets
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However, like Ptolemy,
Copernicus also believed that
the planets orbited in perfect
circles.
It was Johannes Kepler who
realized after carefully studying
the planets movements that the
planets actually moved in oval
orbits called ellipses.
Revolutions and Rotations
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Kepler knew the planets
orbited the sun, but how?
Isaac Newton realized that
a planet’s motion around
the sun is a result of:
inertia and gravity.
Inertia cause the planets
to move in a straight line
and gravity pulls them
toward the sun.
Revolutions and Rotations
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Another way to say a planet
orbits the sun is to say it
revolves around the sun.
The time it takes a planet to
make one revolution around
the sun is called its period of
revolution.
Aside from revolving around
the sun, planets also spin or
rotate on their axis.
The time it takes a planet to
rotate on its axis is its period of
rotation.
A Trip Through the Solar
System
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The planets of our
solar system have a
wide variety of
surface and
atmospheric
features.
Each planet has its
own story to tell.
Mercury
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Mercury is the closest planet
to the sun and is its own
crater-covered world.
The craters on Mercury were
created billions of years ago,
but without weather, there has
been no change.
Mercury is one of the hottest
and one of the coldest planets
in the solar system.
Mercury contains steep cliff
and vast plains, most likely
formed by volcanoes during
the planet’s formation
Venus-The Greenhouse in the Sky
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Venus has about the same
diameter, mass, and density as
Earth. For this reason it is
called Earth’s twin.
Astronomers were unsure
about the surface of Venus
because of its thick cloud
cover. The lower level yellow
clouds on Venus are made of
sulfuric acid and carbon
dioxide.
The surface of Venus has an
orange glow and is dotted with
the remains of many
volcanoes.
Venus-The Greenhouse in the Sky
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The temperatures on Venus
can climb to 480°C, which is
hotter than the surface of
Mercury.
The heat from the sun caused
the water on Venus to
evaporate into the atmosphere
causing a tremendous
greenhouse effect. This
eventually caused the oceans
to evaporate completely.
Venus also has a retrograde
rotation, which means it
rotates from east to west.
Mars-The Rusty Planet
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As you approach Mars, the first
thing you would notice is the
reddish color. This is because
Martian soil is covered in rust!
The surface of Mars is rocky
and covered in craters.
Mars gives evidence to a very
active past. It is also home to
the largest know volcano in the
solar system
Today there is no liquid water
on Mars, but frozen water can
be found on Mar’s polar ice
caps.
The Asteroid Belt
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On your way from Mars to Jupiter you
will enter the asteroid belt.
The asteroid belt contains hundreds of
thousands rocks and “flying
mountains.”
Asteroids are made of rocks, metals, or
a combination of the two.
Most asteroids are small and irregularly
shaped.
The asteroid belt formed from pieces
of matter that failed to join during the
solar systems formation.
Scientists suspect that Jupiter’s
gravitational pull kept the asteroids
from coming together
Jupiter
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Jupiter is the largest planet in our
solar system.
Jupiter is made of primarily hydrogen
and helium gases.
Scientists believe that if Jupiter had
grown larger during its formation,
gravity might have caused nuclear
fusion to occur and a star to form.
One of Jupiter’s most well know
feature is the Great Red Spot, which
is a huge hurricane type storm that is
three times the size of Earth and has
lasted for more than 100 years.
Due to the pressure near the center
of the planet, the dense clouds
become an ocean of liquid hydrogen.
Jupiter
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This liquid metallic layer of Jupiter is the cause of its
gigantic magnetic field called the magnetosphere.
Jupiter is also strange in the fact that it gives off more
heat than it receives from the sun.
It also has a total of 16 moons that circle it, but there
are 4 very large moons discovered by Galileo.
IO is the closest of Jupiter’s moons and is very young
and active.
EUROPA is ice covered and extremely smooth due to its
volcano that spews water and ammonia ice.
GANYMEDE is Jupiter’s largest moon and is the largest
in the solar system. It is about 1/2 rock and 1/2 water
and is the only other object in the solar system known
to have earthquakes.
CALLISTO is the most heavily cratered object in the
solar system and is a very quiet moon.
Saturn-A World of Many Rings
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Saturn is surrounded by seven major
rings made up of icy particles.
Saturn is made mainly of hydrogen
and helium gases and spins very fast
on its axis, which causes its poles to
flatten.
Saturn, like Jupiter, also has violent
storms.
Saturn’s clouds also form the colored
bands we see.
Saturn also has a very small density
and would actually float in water.
Saturn has 21 known moons with the
largest being Titan.
Uranus-A Planet on Its Side
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Uranus is the seventh planet in our
solar system and is almost twice as far
from the sun as Saturn.
Uranus is also a gas planet made of
mostly hydrogen, helium, and methane.
Strong evidence was found that Uranus
is covered by an ocean of superheated
water than may have formed from
melted comets.
The axis on which Uranus rotates is one
the most unusual features. The axis is
tilted at an angle of about 90°. This
makes it look like it is tipped completely
on its side.
Neptune
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Upon examining the orbit of Uranus,
astronomers noticed that there must be
an object beyond Uranus.
Neptune is a giant bluish world.
Neptune is often called a twin to
Uranus because they are about the
same size, mass, and temperature.
Neptune’s surface is probably and
ocean of water and liquid methane,
covering a rocky core.
Data was also found to indicate that
Neptune has five rings made of dust
particles.
Neptune also has at least 8 moons the
biggest and most well known being
Triton.
Pluto-A Double Planet
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Pluto is little more than a moonsized object than may be an
escaped moon of Neptune.
Pluto is made of icy gases such
as methane.
Pluto is the only planet with an
atmosphere on its sunny side
and none on its dark side.
Pluto also has a moon that is so
close in size that it may be
double planet.
Planet X-The Tenth Planet?
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After discovering Pluto, scientists
realized that it was too small to
be pulling on Uranus and
Neptune.
This causes scientists to believe
there is another planet as far as
80 billion kilometers from the
sun pulling on the planets
causing their strange orbits.
Other scientists feel that they are
being pulled on by a Brown
Dwarf or possibly a black hole.
Comets
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Most comets come from the
Oort cloud, which is a vast
collection of ice, gas, and
dust.
The pull of gravity from a
local star pulls parts of this
cloud out into space.
Comets are made up of this
ice, gas, and dust, which
form a cloud around the core
as it heats up.
Meteoroids, Meteors, and Meteorites
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Meteoroids are chunks of
metal or stone that orbit the
sun.
When the meteoroid enters
the atmosphere, friction
causes it to burn. The
streak of light in the sky is
called a meteor.
Most meteors burn up in
the atmosphere, but a few
strike the Earth’s surface
and are called meteorites.
Exploring the Solar System
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Rocketry
Rocketry is based on
Newton’s third law of
motion.
In a reaction engine, such
as a rocket, the rearward
blast of exploding gases
causes the rocket to shoot
forward.
However, rockets must be
able to escape Earth’s
gravitational pull.
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Escape Velocity
In order for a rocket to
escape Earth’s pull, the
rocket must achieve the
proper velocity.
The escape velocity of a
planet is determined by the
mass of the planet and the
distance of the rocket from
the planet’s center.
Rockets also need a fuel
source that will continue to
burn.
Live Long and Prosper!!!