FREE ESSAY ON EARTH - PERFECT PLANET

EARTH - PERFECT PLANET

What is required for a planet to be able to support life? This is a question that people
have been trying to answer for many years. Earth is a very unique planet because it is
the only one proven to support life. Living organisms need certain things in order to
survive that are not found on any other planet. Some of these life supporting features
include food, water, atmosphere, temperature, rotation, gravity, surface and a moon.
First, living things need a source of food. Energy is needed in order for living things
to grow. Our main source of energy on Earth comes from the sun. Plants use the light from
the sun for photosynthesis, and plants source of food comes from photosynthesis. While
animals don't need the sun to produce their own food they do eat plants, and all plants
go through photosynthesis. Planets that are far from the sun, such as Pluto, can not use
the sun's light to produce food. Photosynthesis could never happen on Pluto. Therefore,
there will never be any life on Pluto. In addition, living things also require water.
Plants and animals both need fresh liquid water. Water is important to living things
because it helps change energy from one form to another, such as light to food. Earth is
the only planet known to have a large amount of liquid water. Mars does have polar ice
caps, but no liquid water. Life can not survive on a planet with no liquid water.
Another unique feature of Earth is its atmosphere. A planet without an atmosphere, like
Mercury, could never have any life. Living things have to breathe. If there is no
atmosphere, then there is no gas for plants and animals to breathe. Our atmosphere
contains oxygen and carbon dioxide, along with many other gases. Animals breathe oxygen
and plants breathe carbon dioxide. Venus also has an atmosphere, but it contains mostly
sulfuric acid, plants and animals can't live on Venus because the air is not breathable.
Also, Earth's temperature is perfect for supporting life. Earth's average temperature is
15C. Any other planet would either be too hot or too cold for life. Earth's
perfect temperature is due to many things. Our distance from the sun determines how much
of the sun's heat we get. Our rotation of 24 hours ensures that no one side of Earth
faces the sun for too long, unlike Venus. Venus' rotation is so slow that it is very hot
on one side and very cold on the other because the side facing the sun faces it for so
long that it can't cool off, and the side facing away from the sun cools off for too
long. Along with all of these things, the main factor that controls Earth's temperature,
is our atmosphere. Our atmosphere causes us to experience the greenhouse effect. The
atmosphere holds in the heat from the sun, trapping it so we don't get too cold. 
The speed of earth's rotation is very important to sustaining life. If our planet were to
spin as fast as a planet like Jupiter, then important things would just fly off Earth.
Solid things would fly off because of Earth's gravity, but the gas in our atmosphere
would, and so might our water. If Earth rotated slower, then our temperatures would be
effected. Earth is rotating at a perfect speed. Gravity is also very important for life.
Gravity help hold things on a planet. If the Earth had less gravity, like Pluto, things
would float away. The presence of a surface on a planet is also important. If you tried
to stand on Jupiter you would sink to the core of the planet. This would happen because
Jupiter is made of gas and has no surface, also Jupiter's gravity is more than twice as
much as Earth's, so it pulls things to the center of the planet. Earth has a surface to
stand on and enough gravity to hold thing on the surface.
Lastly, Earth's moon helps support life. We couldn't live without it. Our moon is so
large that its gravity effects us. Our moon helps keep Earth tilted on its axis. Our moon
stops us from wobbling on our axis, like Mars does. If Earth started to wobble it would
effect our climate, but most life would still survive. However, life would not survive if
Earth's rotation sped up. The moon as been slowing down the Earth's rotation ever since
the moon has been our moon. If we lost it the earth would speed up again, and all life
would vanish.
For the reasons above, Earth is a perfect place to live. If any of these factors were
eliminated, there would be no life on Earth. Life could not survive on any other planet
because while there are planets with some of these features, there is no planet except
Earth with all of them. Hopefully we will never have to leave Earth and find a new planet
to inhabit because it would be very difficult to find one as perfect as Earth.