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							The Solar System
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e Solar System
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        THE SUN



The diameter of the Sun is about 1.4 million km
across.
It has an average surface temperature of
5800K.
At its equator, the Sun turns once every 25
days.
Because the Sun is a large gaseous body, it
spins
 at different rates at different places.
The Sun is somewhat flattened, the poles spin
fastest and the
 equatorial regions are slowest.
                        Venus
                        The Planet of Extremes




 Venus was at one time thought to be the planet that was most like the
 Earth. It was often even referred to as Earth's sister planet. Venus is
 95% the size of the Earth, has a density close to Earth's and is only
about 30% closer to the Sun. So there were many reasons to believe
Venus might be just like the Earth only a little warmer. It has only been
   in the last 10 or so years that we have discovered that Venus is
                        anything but Earth's twin.
Venus is a blistering inferno with temperatures exceeding 880 degrees
                                  F and
                    weather which rain sulfuric acid!
                 MERCURY



  Mercury is a small world (4878 km in diameter) only
40 percent larger than our Moon. It orbits close to the
 Sun, a third closer than Earth and speeds through a
year in just over 87 days. Mercury spins slowly on its
          axis, taking 58.6 days to turn once.

  Mercury has a surprising temperature range of -173 to
 430 C. It also has a very high density of 5.44 g/cm3. It
is not a world we would want to visit, nor one where life
              could be expected to survive.
                       Earth

Compared to all of the other places in space we know of: our
planet is indeed an oasis on space. It is the only world we know
where we can exist without elaborate life support. We evolved on
this small blue world and it will remain our home until we are able
to reach for other worlds.
    Earth is not a particularly large planet, with a diameter of
12,756 km. It is also interesting that a typical view of the planet
would be a water world. Indeed, 75 percent of the Earth is
covered by water!
    Orbiting 1.49 x 108km from the Sun, the Earth moves around
the Sun at 29.8 km/sec. One trip around the Sun is one Earth
year and it is our planet's 23.5 degree axial tilt which gives us our
seasons.
    Earth is the largest of the terrestrial planets, and its geologic
history is fairly well understood. Because the planet is partially
molten, the surface is active with plate tectonics. The surface of
the Earth is ever changing, both by natural processes and
processes by man.
                             Mars




   Mars has a diameter of 6796 km, about half the size of the
Earth. A day on Mars is 24 hours 37 minutes almost exactly the
same as Earth's. The Martian year is 687 days slightly less than
twice the length of a year on Earth.
   In some ways, Mars is quite similar to Earth. The red planet's
axial tilt is 25.2 degrees, very close to the Earth's. Mars also
displays seasons, polar caps and geological features of the
grandest scale, Mars is a fascinating planet!
                    JUPITER
        Lord of the Solar System



   Jupiter contains over 70 percent of the total
planetary mass. This planet is truly the lord of the solar
system. It is not just the largest planet, it has a
diameter over 11 times the diameter of the Earth, and is
over 320 times more massive. Jupiter is a ringed
world, surrounded by many moons, some of which are
the most interesting objects in the solar system.

Beyond Mars, the solar system becomes a different
place altogether. The planets are no longer small rocky
worlds, they become ice giants that would dwarf the
Earth. Out here, the solar system is so cold that
hydrogen and hydrogen rich gases could be captured in
the planet making process. Because there was so much
of this type of this building material available, the
planets formed on a grand scale of size.
                SATURN




Considered one of the gas giant planets, Saturn is
smaller and colder than Jupiter.
The planet has a diameter of 120,660 km, about 9.5
times the diameter of the earth. Saturn takes 29.5 years
to orbit the Sun at a distance of 1427 million km.
Like Jupiter, Saturn has a fast rotation rate, turning on
its axis once every 10 hours 14 minutes. This has the
effect of flattening Saturn at its poles, though not as
noticeably as Jupiter.
        URANUS



Minimum Distance from Earth: 2.57
billion km (1.6 billion miles).
Diameter: 51,488 km (32,000 miles). It
takes 84 years to circle the sun.
Uranus has 21 moons.
        NEPTUNE


Minimum Distance from Earth: 4.3
billion km (2.68 billion miles).
 Diameter: 49,493 km (30,760 miles). It
takes 165 years to circle the sun.
 Neptune has eight moons.
PLUTO




Minimum Distance from Earth: 4.34 billion
km (2.7 billion miles).
Diameter: 2,301 km (1,430 miles). It takes
248 years to circle the sun.
Pluto has one moon.
 1   Venus     11
 2   Mercury   11
 3   Mars      11
 4   Earth     11
 5   Jupiter   11
 6   SUN       11
 7   Saturn    11
 8   Neptune   11
 9   Pluto     11
10   Uranus    11
              ANSWERS
     Quiz 1

 1    FALSE
 2    FALSE
 3    FALSE
 4    FALSE
 5    FALSE
 6    FALSE
 7    FALSE
 8    FALSE
 9    FALSE
10    FALSE