Page 187 - Innovator's Science-8

scenario would make it nearly impossible for most life forms–including
humans, animals, and plants–to survive.

While certain microorganisms like some bacteria can exist in icy
environments, scientific evidence so far shows that liquid water is essential
for life to originate and thrive. Earth’s location lets water exist mostly as a

liquid, which is crucial for all forms of life.
This optimal zone around a star

where conditions allow water to
stay, liquid is known as the habitable
zone— or more charmingly, the
“Goldilocks zone ,” where it’s not too

hot, not too cold, but just right for
life.
The habitable zone around a star
We all know, a large part of Earth’s surface is covered by water. From space,
this gives our planet a blue appearance, earning it the nickname “Blue
Earth – The Blue Planet
Planet.”

DID MARS EVER SUPPORT LIFE?
Mars is located at the outer edge of the Sun’s habitable zone. Over the
Sears, many spacecrafts have been sent to Mars, and robotic rovers have

explored its surface. So far, no evidence of life has been discovered.
However, scientists believe that Mars may once have had liquid water-
possibly even lakes and conditions that could have supported simple life
Mars
forms.
This possibility keeps Mars a topic of great interest for scientists. It also
highlights an important aspect of science: it doesn’t always provide final
answers. As exploration continues, new clues may be uncovered-

10,000 km or even new forms of life. Scientific understanding evolves as we
Exosphere
discover more.

Thermosphere 690 km
EARTH’S SIZE AND ITS ROLE IN SUPPORTING LIFE

Mesosphere 85 km Apart from its perfect position in the solar system, Earth’s size also
plays a vital role in making it habitable. Like most planets, Earth
Stratosphere
50 km
moves in a nearly circular orbit around the Sun, ensuring consistent
Troposphere 20 km
levels of sunlight and heat throughout the year. This helps prevent
extreme seasonal changes in temperature at most places.

But being at the right distance isn’t enough. Earth is also the ideal
size to retain an atmosphere— a layer of gases that surrounds the
Earth's atmosphere
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