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| Life on Earth is centered around water. (Credit: Astrointerest). |
‘Life’ is
one of the most mysterious words. The planet Earth is the only known
place where life exists. Astronomers are too keen to know about the existence
of life on other places than Earth. Lot of new techniques and experiments
are done daily to observe evidences of life outside the planet Earth. Let
us look at some basic requirements for existence of life on any planet or moon.
The two fundamental requirements are
moderate temperature range and
source of energy. Habitable temperature range is necessary for most of the
biochemical reactions and also for stability of molecules. Life cannot exist
with too high or too low temperature.
The
source of energy is fundamental need of life; all the activities of life are
powered by energy. Source of energy may include host star, planet’s internal
energy or some radioactive decay. In case Earth, the main source of energy is the
Sun. Plants are the main absorber of energy from the Sun and then they transfer
it to other organisms. In case of moons, planet may play role of energy source
like the planet Jupiter and the planet Saturn.
Energy on
moons may also generate from tidal forces applies by planet like Io which is
moon of Jupiter, it has volcanoes on its surface due to tidal forces
of the planet Jupiter that provide very high temperature and energy.
Now there
are other requirements also which are necessary. The Green House Effect is
somehow related to the maintenance of constant temperature in day and night.
Green House Effect may increase the temperature by large amount like nearly 500
degree Celsius on the planet Venus.
Atmosphere
is required to protect life from meteorite hits and some radiations like Ultra
Violet Radiations in case of ozone layer. The size of meteors reduces up to
zero and burn out completely when they travel through atmosphere. The
atmosphere of Earth also protects us from the cosmic radiations and
neutron radiations.
Magnetosphere is also necessary to protect life from Solar Radiations and also planetary radiations in case of moons. The planet Jupiter and Saturn emit radiations of heavy particles which have ability to degrade atmosphere of moons and also destroy life. Ganymede is the only moon of Solar System which has its own magnetic field.
Magnetosphere is also necessary to protect life from Solar Radiations and also planetary radiations in case of moons. The planet Jupiter and Saturn emit radiations of heavy particles which have ability to degrade atmosphere of moons and also destroy life. Ganymede is the only moon of Solar System which has its own magnetic field.
The life
on Earth is mainly centred on water and some elements like C, N, O
and H etc. But it is not necessary that life needs water to exist. Water is
good solvent and provides medium for large number of reactions but other
chemical may also play same role in some other planet to support life.
Carbon
forms large number of molecules that enables life to exist on Earth.
Nitrogen helps in producing amino acids and DNA. But life may use different
molecular structures which can be totally different from the case of Earth.
Although
water, carbon and oxygen provide easy evidences for existence of life but
universe is not very small it might be possible that somewhere in the universe
life is growing in some unknown environment which cannot be imagined easily
just by looking at life on Earth.