Mercury
The planet Mercury is the closest of the planets to the Sun. Because this planet lies so close to the Sun, and as a result somewhat near to Earth, it is visible to observers on Earth in the late evening or early morning sky. Because of this, Mercury has become a part of the mythology and legend of almost every culture throughout the history of the Earth.
This planet is often called a morning star. This is because Mercury shines brightly in the early morning just before the sun rises. It has also been called an evening star for the same reason. Mercury is often visible for a brief period of time just after the Sun sets.
Mercury Has No Atmosphere The planet Mercury is too small and has too little gravity to hold onto an atmosphere. Any gases released from the planet quickly escape into space. Also, Mercury is so close to the Sun that any atmosphere is quickly blown away by the Sun's solar winds. That means that there is almost no air on Mercury.
Venus: Earth's Twin
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| Venus is called the Evening Star. It is called this because it looks so bright to us from Earth. |
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| Venus |
Venus and Earth are almost the same size. Venus is the closest planet to
Earth, but it does not have oceans or human life like Earth. Venus gets so hot
during the day that it could melt a lead cannonball. The temperature rises to
484 degrees
Celsius on
the side facing the Sun. Venus has very thick, rapidly spinning clouds which
cover its surface. These clouds hold heat in. That is why Venus gets so hot.
These clouds also
reflect
sunlight. That is why Venus appears so bright to us here on Earth. There are
constant thunderstorms in these clouds. Venus has several large inactive
volcanoes.
Much of the surface is covered by old lava flows from these volcanoes.
Venus is unusual because it
rotates in
a direction opposite that of all of the other planets. Venus spins very slowly
as it
orbits the
Sun
| Earth: The Water Planet |
| Seventy percent of the Earth's surface is covered by water. The
remaining 30 percent is covered by mountains, volcanoes,
deserts, plains, and
valleys.
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Earth is the third closest planet to the Sun. It has an atmosphere
made up of many different gases, but
mainly it is nitrogen and oxygen. The atmosphere gives us air to breathe. We
live on the planet Earth.
The Earth orbits
around the Sun. It takes one year to go around the Sun one complete time. The
Earth also rotates, or
spins, on its axis. It
takes one day to spin around one complete time. The Earth's axis is not straight
up and down, but tilted a little bit. This tilt is responsible for us having
seasons. Otherwise, the temperature would be pretty much the same all year long.
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| Mars: The Red Planet |
| Some of the meteorites
found on Earth are actually pieces of the planet Mars. As of June 2006,
thirty-four "Martian meteorites" have been found.
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The temperature on Mars can be very, very cold. On its warmest day, Mars can
still be a very cold place. At the top and bottom of the planet are poles just
like on Earth. During the Martian winter, ice caps can be seen at the poles.
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| Mars |
Space
probes have landed on Mars. These probes were sent on a fact-finding mission
by the United States. They performed experiments on the Martian dirt and atmosphere.
The dirt was found to contain clay which was rich in iron. The iron is what
gives Mars its red color.
Mars has many craters
which were formed by meteorites
or asteroids
hitting it. Mars also has some of the tallest volcanoes
and some of the deepest valleys in
our solar
system. Mars has two moons, Phobos and Deimos which have unusual shapes.
Scientists think these potato-shaped moons were once asteroids captured by Mars'
gravitational
pull .
| Jupiter: The Largest Planet |
| Jupiter is so large that all of the other planets in the solar system
could fit inside of it.
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Jupiter is a large gas planet
whose clouds change colors daily. This planet is made mostly of hydrogen and
helium gases. Jupiter gives off two times more heat than it gets from the Sun.
It shines very brightly in the night sky for nine months of the year when it is
closest to Earth. Huge areas of swirling gases can be found in Jupiter's atmosphere.
The largest swirling area of gas is called the Great Red Spot. Scientists
believe this is a large hurricane-like
storm which has lasted for hundreds of years. Large bolts of
lightning have also been seen in Jupiter's atmosphere. Pictures taken by space
probes have shown thin rings around Jupiter. As of January 2011, Jupiter has
50 named moons. 13 more have been discovered but not given official status or
names. One of Jupiter's moons, Io, has active volcanoes
on it. Areas on Io that are near the volcanoes are very, very hot.
| Saturn: The Ringed Planet |
| When seen through a telescope,
Saturn is one of the most beautiful sights in the night sky. It looks like a big
ball inside of rings.
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| Saturn |
Saturn is a very large gas planet
which spins very rapidly on its axis. It
spins so fast that it flattens out the top and the bottom of the planet. The
fast spin also causes Saturn to bulge at its
equator. Saturn's atmosphere
has winds which can blow at over 1800 kilometers
per hour! The white spots on Saturn are believed to be powerful storms. Saturn
is surrounded by over 1000 rings made of ice and dust. Some of the rings are
very thin and some are very thick. The size of the particles
in the rings range from pebble-size to house-size. Scientists believe that the
particles came from the destruction of moons circling the planet. As comets and
meteorites
smashed the moons, Saturn's gravitational
pull shaped the particles into rings. Saturn has at least 53 moons. Some of these moons orbit the
planet within the rings, creating gaps in the
rings.
| Uranus: Neptune's Twin |
| Uranus is one of the smaller gas giants in
our solar
system, but it is still large enough to hold 64 planets the size of Earth.
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Uranus tilts over so far on its axis that it
rotates
on its side. Because of this, its poles are
sometimes pointed almost directly at the Sun. Uranus' atmosphere
is made up of hydrogen, helium, and methane. The temperature in the upper
atmosphere is very cold. The cold methane gas is what gives Uranus its
blue-green color. The rapid rotation of Uranus causes winds up to 600 kilometers
per hour to blow in its atmosphere. Uranus has eleven known rings which contain
dark, boulder-sized
particles.
Uranus has 27 named moons. Some of these moons are less than 100 kilometers wide
and black as coal.
| Neptune: The Blue Planet |
| It is so cold on Neptune that you would need skin thicker than
a polar bear's to stay warm. |
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| Neptune |
Neptune and Uranus are very much alike. They are both large gas planets
that look like big blue-green balls in the sky. Neptune has winds in its atmosphere
which blow at over 2000 kilometers
per hour! This planet has large, dark circles on its surface which astronomers
believe to be storms. Neptune has two thick and two thin rings which surround
it. Neptune also has thirteen known moons.
Four of these moons orbit the
planet within the rings. One of Neptune's moons, Triton, orbits the planet in a
direction opposite to Neptune's other moons. Neptune is the farthest planet from
the Sun. |
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