Our solar system

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Our solar system

• By Mrs. White

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A theory of the beginning.
Scientists believe the solar system began forming
10 to 12 billion years ago as swirling gas and
dust formed a thick core. The core, with most of
the mass, collapsed around 5 or 6 billion years
ago and later became the sun. The remaining
matter swirled into a disk. Some of it crashed
together and formed planets. That's the main
theory, at least, and though most scientists
think that's how it happens, there are a few
other explanations.
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Alternate theory to beginning of Universe

• The big bang theory says that the entire universe
  came to be in a huge explosion about 15 billion
  years ago. Nobody ever believed this idea until
  Edwin Hubble discovered the redshift of galaxy
  light in the 1920s, which seemed to suggest a
  bigger universe. However, our ability to test
  this theory and others have gotten better with
  modern telescopes covering all wavelengths, some
  of them in orbit. Although many people believe
  this theory there is no physical proof that it
  actually happened.

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A little about our Solar System

• As you know, planets are part of our solar
  system. Comets, asteroids and the planets' moons
  are part of the solar system, too. These things
  all orbit around a star we call the sun. And it's
  all held together by gravity.  

• The planets are often divided into two groups
  the four inner planets (Mercury, Venus, Earth and
  Mars) and the five outer planets (Jupiter,
  Saturn, Uranus, Neptune and Pluto).

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MERCURY

• The diameter of Mercury is 3,031 miles.
• It takes the planet 58.6 days to rotate
  completely 360 degrees.
• It takes 88 Earth days for Mercury to rotate
  around the sun.
• Mercury only weighs 5.5 of what earth weighs.
• Mercurys diameter is 38 of what the earths
  diameter is.

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More about Mercury

• Mercury is the closest planet to the sun.
  Because Mercury is so close to the sun (and the
  sun's glare) it is difficult to spot from Earth.

• Mercury's gravity is less than half what we have
  on Earth, so Mercury can hold onto only a small
  bit of an atmosphere. Since there's not much
  atmosphere (which on Earth acts like a warm
  blanket) temperatures on Mercury go crazy. It can
  be a scorching 750 degrees Fahrenheit during the
  day, and minus 320 at night!

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VENUS

• The Diameter of Venus is 7,521 miles.
• It takes 243 days to rotate 360 degrees
  completely.
• It Takes 225 Earth days to orbit the sun.
• It only has 82 of the mass earth has
• Its diameter is about 95 of earths.
• It is a 30 percent closer to the sun that the
  earth.

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More fun facts about Venus

• The second planet from the sun bakes under twice
  as much solar radiation as Earth. Venus reaches
  temperatures of 895 degrees Fahrenheit!
• The thick clouds around Venus rotate much faster
  than the planet itself -- once every four days.
  Not counting the moon, Venus is the brightest
  object in the night sky.

• The surface of Venus is mostly a rocky desert
  (there are many computer-generated that show
  lava flows around a place called Sif Mons). Like
  Mercury, Earth and Mars, Venus is mostly rock and
  metal.
• While all of the planets orbit in an ellipse
  (something like the shape of an egg), Venus'
  orbit is the closest to a perfect circle.
• Because it is often brighter than anything in the
  sky except the moon, Venus is the cause of many
  UFO reports.

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EARTH

• The Diameter of earth is 7,926 miles.
• It takes 23 hours, 56 minutes for the earth to
  rotate completely.
• It takes 365.24 days for the earth to Orbit
  around the sun.

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Cool facts about Earth

• Earth is the third planet from the sun. Like the
  other three planets of the inner solar system
  (Mercury, Venus, and Mars) our planet is made up
  mostly of rock and metal.
• One of the most important things about Earth is
  that there's lots of water, which is one
  important reason why life got started long ago.
  We're also lucky that Earth's atmosphere has
  plenty of nitrogen and oxygen, two other things
  that life needs.

• It may not feel like it but the ground under your
  feet is actually moving very, very fast. The
  Earth's surface is rotating about its axis at
  1,532 feet per second at the equator, and the
  planet zips around the sun at more than 18 miles
  per second! So all of us are going incredibly
  fast -- even when we're standing still.

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MARS

• The diameter of Mars is 4,217 miles.
• It takes 24 hours and 37 minutes for it to rotate
  360 degrees completely.
• It takes 687 days for mars to completely orbit
  the sun.
• It only has 5 of the mass that the earth has.
• It has 53 of the earths diameter.
• Its 150 further away from the sun than the moon
  is.

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THE LOW DOWN ON MARS

• The fourth planet from the sun has always made us
  humans do a lot wondering and hoping. While
  scientists haven't proven there's any life on
  Mars, the dusty red planet is still a fascinating
  place.
• The surface of Mars is more interesting than
  most. Like Mercury, Venus and Earth, Mars is
  mostly rock and metal, but it also has lots of
  mountains and craters.

• The dust that gives Mars the reddish color is
  made of something called iron oxide. Temperatures
  on Mars can get as cold as -207 degrees
  Fahrenheit and as high as 80 degrees Fahrenheit
  on summer days.
• Mars was probably warm and wet about 3.7 billion
  years ago. Mars cooled and the water froze. Some
  of that water still may exist in ice caps at the
  poles.

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JUPITER

• Jupiter weighs over 316 times as much as the
  earth.
• It is also 11.12 times larger than the earth.
• The fifth planet from the sun is mostly a huge
  ball of gas. But at Jupiter's center is a core of
  rock many times the mass of Earth. The whole
  planet is so massive it could hold all the other
  planets put together!

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SATURN

• Diameter 74,900 miles
• Time to rotate completely 10 hours, 39 minutes
• It takes 29.5 years for saturn to orbit the sun.
• The sixth planet from the sun has a rocky core
  and a lot of gas on its surface. But Saturn is
  known for its rings. The mile-thick rings are
  made of tons and tons of ice that orbit the
  planet. Some of the ice bits are smaller than
  marbles, some are bigger than your computer.
• Saturn has 18 known moons, each made mostly of
  ice and rock.

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URANUS

• The diameter of Uranus is 31,763 miles long.
• It takes the planet 17 hours and 54 minutes to
  turn 360 degrees.
• It takes 84 years for uranus to orbit the sun.
• It weighs 14.5 times as much as the earth
• It is 4.1 times heavier than the earth
• The seventh planet from the sun is a lot like its
  neighbors, with a cloudy surface, rapid winds,
  and small rocky core.
• Uranus rotates at an extreme tilt of 98 degrees,
  sort of on its side. This causes one pole to
  point toward the sun for decades, giving the
  planet strange seasons. Scientists think the
  planet might be on its side because some other
  large object crashed into it a long time ago.

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NEPTUNE

• The eighth planet from the sun (well, some of the
  time it's eighth, but more on that later) has a
  rocky core surrounded by ice, hydrogen, helium
  and methane.
• Like the other gas planets, Neptune has rapidly
  swirling winds. Its quick rotation causes fierce
  winds and some very strong storms. The planet has
  eight known moons. Like Saturn, Neptune has
  rings. But Neptune's rings are not as thick, and
  they are hard to spot.
• Neptune was discovered in 1846.

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PLUTO

• The mass of pluto is .2 of the earth.
• The diameter is only 18 of what the earths is.
• Pluto, which is smaller than our moon, is a cold,
  dark, frozen place. We don't know very much about
  the tiny planet. Scientists think it is made of
  rock and ice. It might have a thin atmosphere of
  nitrogen, carbon monoxide and methane.
• Some astronomers think Pluto may have wandered
  into the system from a more distant place called
  the Kuiper Belt. In the Kuiper Belt, Pluto-like
  objects and comets orbit the sun. So maybe Pluto
  is not a planet at all, but more like a large
  asteroid or comet. Some scientists say Pluto may
  be an old moon of Neptune that escaped.

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REFERENCE PAGE

• Space kids

Big bang theory