MOVEMENT IN THE SOLAR SYSTEM

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MOVEMENT IN THE SOLAR SYSTEM
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The sun is a huge ball of glowing gases at the
center of the solar system. This star supplies
light energy for the earth and for the other
planets that move around it. Without this light
energy, the earth would be a cold, dark planet.
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Many years ago, people watched the sun rise,
move across the sky, and then set. They
believed that the earth was still and that the
sun was moving around the earth. We now know
that the sun only appears to rise and set. It is
the turning of the earth that causes sunrise and
sunset.
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The earth is like a ball that is spinning on
someones finger. The earth spins on an
imaginary line called an axis. Each time
the earth goes around it is called a rotation.
The rotation makes day and night. As the earth
turns, the part that faces the sun has day and
the part away from the sun has night. The length
of time for the earth to rotate is one full day.
It takes 24 hours for the earth to rotate.
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REVOLVING AROUND THE SUN
As it spins, the earth also moves around the
sun. This movement is called revolving. The path
that the earth takes around the sun is called
the orbit. When the earth completes one complete
path around the sun it is called one revolution.
It takes the earth one year to complete this
trip. So a revolution takes about 365 days.
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Movement and Tilt - Together
If the earth was straight up and down on its
axis, sunlight would always hit the earth at the
same angle. However, the earth is tilted and as
it makes its revolution around the sun different
parts of the earth get more sunlight than others.
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WHAT DOES THE MOONS MOVEMENT CAUSE?
You have seen the brightness of a full moon on a
dark night. However, the moon does not make its
own light. Moonlight is actually sunlight
reflected from the moon.
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PHASES OF THE MOON
Even though the moon is shaped like a ball,
its shape seems to change from day to day.
Those different shapes are the moons phases.
Sometimes it appears that the moon is a
full circle. This is a full moon.
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As the moon revolves around the earth, a
part of the dark side of the moon faces the
earth. As the days pass, people see more of the
dark side and less of the moon. The moon slowly
changes to a half circle. When the moon is a half
circle, half of the moon is lit, and half is
dark. This is called a half moon. As time
passes, only the dark side of the moon faces the
earth. The moon does not appear in the sky. This
is called a new moon, though it is really not
new. The moon is beginning a new set of phases or
stages. The new moon takes place a little more
than two weeks after a full moon.
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The moon slowly changes from the new moon
back to a full moon. The changes from a full
moon, to a new moon, and back to a full moon
take 29 1/3 days. The moon takes this long to
revolve around the earth once.
June 24 June 27
June 12 June 15 June 18 June
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June 30 July 2 July 5
July 7 July 8
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ECLIPSES OF THE MOON
As the moon revolves around the earth, the
earth usually does not come between the sun and
the moon. When the earth does come between the
sun and moon the moon will pass through the
earths shadow, which causes a lunar eclipse.
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The moon usually does not come between the
earth and the sun. When it does, the moon blocks
some sunlight from the earth, and a solar eclipse
takes place. The moon makes a small shadow on
the earth. From this shadow, the sun appears to
get covered slowly.
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HOW DO THE PLANETS OF THE SOLAR SYSTEM MOVE ?
For thousands of years, people have watched
the stars at night. The stars appear to rise and
set slowly as the night goes on. The stars and
sun make their own light. From night to
night, some points of light seem to move among
the stars. These are the planets. Planets, like
the earth and moon do not make light. They get
light from the sun. It has been known for
more than 500 years that planets are satellites
of the sun. That means that they go around the
sun.
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This model represents the scale size of the nine
planets as they are in orbit around the sun.
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THE
PLANETS Mercury Venus Earth Mars Jupiter Satu
rn Uranus Neptune Pluto
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MERCURY
Time for orbit - 88 days Time for rotation-176
days Moons - 0
This picture represents the hills on Mercury.
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Mercury
Mercury is covered with large holes called
craters. These craters were formed when Mercury
was hit by huge rocks from space. Because
Mercury is closest to the sun, it is very hot.
The temperature on Mercury can reach 425 degrees
Celsius. Mercury is less than half the size of
Earth and has no moons.
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VENUS
Gula Mons - a volcano
Eistla - A Rift Valley
Time for orbit - 8 months Time for rotation -
127 days Moons - 0
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This is a picture of the Arachnoids, one of the
most interesting things about Venus. Notice how
the land is spiral-shaped.
This picture was taken using special equipment so
that the different elevations of Venus would show
up.
Venus is about the same size as Earth. It is
always covered with clouds. These clouds are made
from drops of acid. The air is mostly carbon
dioxide. Venus has giant volcanoes.
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EARTH
Time for orbit - 1 year Time for rotation - 1
day Moons - 1
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MARS
As you look at the pictures you will notice that
Mars is much like Earth.
Time for orbit - 1.9 years Time for rotation-25
hours Moons - 2
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Mars
Mars is covered in reddish dust and rocks.
Winds blow the dust into the air and make the sky
pink. Mars has giant volcanoes. It also has a
giant canyon much larger than the Grand Canyon on
Earth. The temperature on Mars is usually
lower than on Earth.
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JUPITER
Time for 1 orbit - 12 years Time for rotation
-10 hours Moons - 16
Notice the large red spot on Jupiter. It is a
large storm that is larger than Earth.
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Jupiter
Jupiter is the largest planet. Some of its
moons are bigger than some of the planets. One
of its moons even has volcanoes. Unlike the
other planets, Jupiter gives off energy that
heats the gas above it.
These are the rings of Jupiter.
This is the Giant Red Spot on Jupiter. It is a
storm that is larger than the Earth.
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SATURN
Time for 1 orbit - 29.5 hours Time for rotation
- 10 hours Moons - 17
Saturn is the 2nd largest planet. It has many
moons. Saturn has storms and gives off energy
that heats the air above it. Saturn has bands
that are harder to see than Jupiters bands. It
has beautiful rings that are made of thousands of
thinner rings.
Here is a close up of the rings.
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URANUS
Time for 1 orbit - 84 years Time for 1 rotation
- 17 hours Moons -15
Uranus is 4 times larger than Earth. It is so far
away that it is very cold. Uranus is a blue-green
color because of a gas that is around it. Uranus
has at least 10 narrow rings.
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NEPTUNE
Time for 1 orbit - 165 years Time for rotation -
18 hours Moons -2
Not much is known about Neptune and Pluto.
Neptune is a large planet that looks greenish.
Scientists hope to learn more about Neptune in
the future.
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PLUTO
Time for 1 orbit - 250 years Time for 1 rotation
-6 days Moons -1
Pluto is the smallest planet. It is about the
size of Earths moon.
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Meteors and Asteroids
A meteor is a piece of rock or dust from space
that burns up in the earths air. People see
meteors as flashes of light crossing the sky.
Some people call them shooting stars, but they
arent stars at all. Meteorites are any part of
the meteor that reaches the Earth. Asteroids
are rocky objects that orbit the sun between the
planets. The largest asteroid is about the same
size as the state of Texas.
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Comets
Large chunks of ice and dust orbit the sun.
These are called comets. Comets have orbits that
are much longer and flatter than the planets.
Comets can not be seen from the earth when they
are far away in their orbit. When comets are
far away from the sun, they do not get much heat.
As comets move closer to the sun, the
suns energy begins to heat them. Some of the
ice becomes a gas. The sun pushes the gas and
dust into a long tail. The tail goes from the
bright part of the comet known as the head.
A comets tail can be millions of kilometers long.