When seen from space, Earth looks like a beautiful blue and white ball. It is
the largest of the inner planets and the third planet from the Sun. It is the
only planet which can support life and has liquid water on its surface.
ago, when a meteorite hit the Earth
and wiped out the dinosaurs.
The pattern of ice ages we see today
began about 40 million years ago,
Scientists say the Earth was formed and became worse during the
about 4.57 billion years ago from a Pleistocene period about 3 million
solar nebula which is a disk-shaped years ago. The Polar Regions have
collection of dust and gas. Originally also gone through frequent cycles of
liquid, the outer layer cooled to form icing over and thawing every 40–
a crust, and volcanic activity 100,000 years. The last ice age was
produced the primitive atmosphere. 10,000 years ago.
The surface constantly changed over
hundreds of millions of years, as
continents were created and then
destroyed. They moved together
until they formed a super continent.
Scientists believe there have been
five mass extinctions over the last
535 million years. They say the last
extinction occurred 65 million years
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Earth’s surface layer is a hard, rocky
crust formed from which cooled 4.5
billion years ago.
Mountain ranges are formed when
two plates smash together and their
The inside of the Earth is divided into
edges are forced up. Other features
four layers, the outer crust, the
are also formed from the moving
mantle, a liquid outer core, and a
plates. The Earth's landscape
solid inner core.
changes from place to place.
The temperature at the center of the
The surface changes over time as a
planet may be up to 7,000 K, and is
result of movement of the plates and
caused by the radioactive decay of
erosion. The surface areas formed or
minerals.
broken down through plate
movement suffer from weathering,
The outermost part of the interior is
thermal cycles, and chemical effects.
two layers: the lithosphere and the
solid uppermost part of the mantle.
Below the lithosphere is the
asthenosphere, the inner part of the
mantle.
The lithosphere is broken into
tectonic plates. Earthquakes,
volcanic activity, mountain-building,
and oceanic trench formation occurs
along these plate boundaries. The pedosphere is the outside layer
of the Earth made of soil. Nearly
forty percent of the Earth's land
surface is used for cropland and
pasture.
Earth’s atmosphere is made of
gases which surround the planet and
are held there by gravity. It is made
of nitrogen, oxygen, argon, carbon
Seventy percent of the Earths dioxide, trace amounts of other
surface is covered with water, and gases, and water vapor. This is
thirty percent is landmasses. The known as air. The atmosphere
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absorbs ultraviolet solar radiation every 365.2564 mean solar days or
and decreases temperature changes one year.
between day and night.
As you see, the Earth is an
amazing planet and there is tons
of interesting facts out there if you
just look. If you would like to
learn more about planet Earth,
please visit the following
websites.
www.aas.org
Other functions of the atmosphere www.britanica.com
include: www.cotf.edu
www.earthchanges.com
transporting water vapor, www.en.wikipedia.org
providing useful gases, www.learner.org
causing small meteors to burn www.nasa.govewww.scotese.com
up before they strike the www.washingtonpost.com
surface, www.windows.ucar.edu
and moderating temperature.
The Earth's atmosphere has no
clear-cut boundary, as it slowly
becomes thinner and fadesinto outer
space.
Earth is similar to the other inner
planets. Mercury is the closest to the
sun, Venus is second, the Earth is
the third, and Mars is fourth. All of
these planets, including the Earth,
are just balls of rock.
It takes the Earth twenty-three hours,
fifty-six minutes and 4.091 seconds
to rotate around its axis. Earth orbits
the Sun at about 93.2 million miles
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