HOW DOES EARTH SUPPORT LIFE?
Earth, our home planet, is a world unlike any other. The third planet from the sun, Earth, is
the only place in the known universe confirmed to host life.
With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, and it's the
only one known for sure to have liquid water on its surface. Earth is also unique in terms of
monikers. Every other solar system planet was named for a Greek or Roman deity, but for at
least a thousand years, some cultures have described our world using the Germanic word
“earth,” which means simply “the ground.”
Earth is unique because it is the only place in the universe known to host life. Some of the
oldest evidence of microbial life suggests that it was already widespread on our planet 3.95
billion years ago.
What makes Earth sustainable for life?
It is the right distance from the Sun, it is protected from harmful solar radiation by its
magnetic field, it is kept warm by an insulating atmosphere, and it has the right chemical
ingredients for life, including water and carbon. The processes that shape the Earth and its
environment constantly cycle elements through the planet. This cycling sustains life and leads
to the formation of the mineral and energy resources that are the foundation of modern
technological society.
Let’s discuss the factors one by one.
a. Moderate Temperature Range
● The distance of the Earth from the Sun gives the planet the favourable
temperature condition.
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Page 1 ● The Earth and the Sun are equally important because the Earth would be a lifeless
ball of ice-coated rocks without the Sun's heat and light. It regulates the
temperature of water bodies, weather patterns, and provides energy to the
growth of plants. The distance of the Earth from the Sun makes it a perfect reason
for life because it receives the perfect amount of heat and light to allow life to be
created and to support it.
b. Presence of Water
● Water is very important for life because it contains the oxygen needed for life and
allows life-providing molecules to move around easily. It continually changes its
form through the water cycle. The process by which water continually changes its
form and circulates between oceans, atmosphere, and land is known as the water
cycle.
.
● Earth's global ocean, which covers nearly 70% of the planet's surface, has an
average depth of about 2.5 miles (4 kilometers) and contains 97% of Earth's water,
while the 3% is freshwater that consists of ice-cap, groundwater, freshwater lakes,
inland, and salt lakes.
c. Favorable Atmosphere
● Near the surface, Earth has an atmosphere that consists of 78% nitrogen, 21%
oxygen, and 1% other gases such as argon, carbon dioxide, and neon.
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This document contains proprietary and confidential information. Reproduction, redistribution, or forwarding to
anythird party, in whole or in part, is strictly prohibited unless made with prior written consent from APEC Schools.
Violation or noncompliance shall be dealt with according to law.
Page 2 ● It is the layers of gases surrounding the earth that consists of the exosphere,
thermosphere, mesosphere, stratosphere, and troposphere. The air content and
favorable atmospheric pressure also supported the life of most creatures. The air
content of carbon dioxide on the Earth is less than that of planets like Venus and
Mars. Hence, the less air content of carbon dioxide helps moderate the Earth's
temperature and is absorbed by plants during photosynthesis to produce oxygen.
● The atmosphere affects Earth's long-term climate and short-term local weather
and shields us from much of the harmful radiation coming from the Sun. The
ozone layer is a part of Earth's atmosphere situated in an area known as the
stratosphere, which protects life on Earth from its potentially harmful effects of
shorter wavelengths and highly hazardous ultraviolet radiation (UVR) from the sun.
d. Availability and Use of Energy from the Sun
● Earth is the only planet that uses the Sun’s light as useful as a source of energy.
That energy is used to convert elements, by living things, into a useable form. A
plant uses the energy provided by the sun to drive photosynthesis and provide
food to grow. As a by-product, oxygen is released, which we then use as an energy
source of our own.
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This document contains proprietary and confidential information. Reproduction, redistribution, or forwarding to any
third party, in whole or in part, is strictly prohibited unless made with prior written consent from APEC Schools.
Violation or noncompliance shall be dealt with according to law.
Page 3 e. Nutrients
● All solid planets & moons have the same general chemical makeup, so nutrients
are present. However, only Earth has a water cycle and volcanic activities that can
transport and replenish the chemicals required by living organisms.
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f. Magnetic Field
● The interstellar cloud of gas and dust that gave rise to Earth contained enough
radioactive elements to power a churning core for billions of years. This creates a
magnetic field that protects the planet from dangers like solar flares.
______________________________________________________________________________________________
This document contains proprietary and confidential information. Reproduction, redistribution, or forwarding to any
third party, in whole or in part, is strictly prohibited unless made with prior written consent from APEC Schools.
Violation or noncompliance shall be dealt with according to law.
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