Why is the Earth Habitable?

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By analyzing our Solar System, scientists surmised that life aroused from
cosmic processes. Terrestrial life is all interrelated in one continuous
web. Plants, our autotrophy, consume carbon dioxide and releases free
oxygen into the atmosphere. Aerobic organisms, which encompass fish,
amphibians, reptiles, and mammals, including us humans, utilize the oxygen,
which is necessary for cellular respiration. As a result of cellular
respiration, a net gain of 36 Adenosine Triphosphates (ATP) are yield, and
carbon dioxide is feed into the atmosphere. This gas exchange process is
called the carbon cycle, and it will be discuss in more details later on.
Further studies of the chemistry of life, prompted scientists to speculate
that the same complex system that governs life may also regulate that of
nonliving system as well. Iron and calcium are examples of elements that
are found in our blood. Most of our fine jewellery made from elements
such as gold and silver. These elements were formed by ancient stars, which
collapsed many billion years ago (our solar system is believed to originate
4.5 billion years ago). In a vague summary, indeed "we are all star stuff,"
and life might be a cosmically commonplace.
If we will make the assumption that life is a cosmically commonplace, we
will find three of mother's nature ingredient for her recipes to cook
life-water, energy, and carbon, the organic molecule. The area where life
can possibly flourish is referred to as the habitable zone, or the
"Goldilocks Zone."
Within this area, life can thrive off the solar energy from our sun, but
it is not so close to it, that organic molecules will eventually denature
and set water to evaporate. However, the more modern definition of the
habitable zone has expanded. Now, the habitable zone may exist beyond our
original understanding of physic and chemistry. It can possibly incorporate
areas where strong gravitational attraction is present, generating
sufficient heat inside the core of the orbiting moon such as Europa and
Titan. Life has proven itself tougher than we imagined.

Hydrothermal Vents-Broadening our understandings.
Hydrothermal vents are geyser on the seafloor. The first discovery of
these vents was made in 1977, and once again revolutionized our
understanding of life. The discovery of these vents, proved to be a
scientific breakthrough, dismissing the concept that sunlight was an
essential factor to support life. These vents spew hot and mineral rich
water, which aid to support a complex diversity of life on the seafloor.
Although the deep sea appears to be seemingly devoid of life, the vent site
has a diverse community of life, which includes tubeworms, enormous clams
and eyeless shrimp.
Hydrothermal vents are now commonly found along the Mid-Ocean Ridge System
at an average depth of 2,100 meters. Along this ridge, tectonic plates are
constantly moving. As the two crustal plates extend in opposite directions,
cracks and crevices are formed. Seawater enters these porous areas, and is
heated by the magma just beneath the plates. As the water approaches
temperature of nearly 400ºC, water will eventually shoot to the surface.
Interestingly, due to the massive pressure present at these depths, water
does not boil due to the unique properties of water. As these extremely hot vents water emerges from the pours of the seafloor, it interacts with the surrounding water, and dissolved metals precipitate to form chimney tops.