PPT: Our Home: Earth, a Unique Life Sustaining Planet | Science Curiosity Class 8 - New NCERT PDF Download

 Page 1


Our Home: Earth,
a Unique Life
Sustaining Planet
Page 2


Our Home: Earth,
a Unique Life
Sustaining Planet
Why Is Earth a Unique Planet?
While there are billions of planets in the universe,
Earth is the only one where life, as we know
today, exists and thrives in all its forms.
All life on Earth exists in just a very thin layer on
the surface of our planet. From the tallest
mountain to the deepest ocean trench, the crust
where all life exists is tiny compared to the size of
Earth.
If Earth were the size of an apple, the crust would
be as thin as the apple's skin - yet this delicate,
life-supporting layer is what makes Earth truly
special.
Page 3


Our Home: Earth,
a Unique Life
Sustaining Planet
Why Is Earth a Unique Planet?
While there are billions of planets in the universe,
Earth is the only one where life, as we know
today, exists and thrives in all its forms.
All life on Earth exists in just a very thin layer on
the surface of our planet. From the tallest
mountain to the deepest ocean trench, the crust
where all life exists is tiny compared to the size of
Earth.
If Earth were the size of an apple, the crust would
be as thin as the apple's skin - yet this delicate,
life-supporting layer is what makes Earth truly
special.
What Do the Planets of Our
Solar System Look Like?
Our solar system has eight planets orbiting the Sun in
nearly circular orbits. In order of increasing distance from
the Sun, they are Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, and Neptune.
Mercury, Venus, Earth, and Mars are relatively small and
rocky planets, while Jupiter, Saturn, Uranus, and Neptune
are large planets, mostly made of gases.
All planets get their energy from the Sun. Generally,
planets closer to the Sun are hotter, with one notable
exception: Venus is the hottest planet due to its thick
atmosphere trapping heat through the greenhouse effect.
Page 4


Our Home: Earth,
a Unique Life
Sustaining Planet
Why Is Earth a Unique Planet?
While there are billions of planets in the universe,
Earth is the only one where life, as we know
today, exists and thrives in all its forms.
All life on Earth exists in just a very thin layer on
the surface of our planet. From the tallest
mountain to the deepest ocean trench, the crust
where all life exists is tiny compared to the size of
Earth.
If Earth were the size of an apple, the crust would
be as thin as the apple's skin - yet this delicate,
life-supporting layer is what makes Earth truly
special.
What Do the Planets of Our
Solar System Look Like?
Our solar system has eight planets orbiting the Sun in
nearly circular orbits. In order of increasing distance from
the Sun, they are Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, and Neptune.
Mercury, Venus, Earth, and Mars are relatively small and
rocky planets, while Jupiter, Saturn, Uranus, and Neptune
are large planets, mostly made of gases.
All planets get their energy from the Sun. Generally,
planets closer to the Sun are hotter, with one notable
exception: Venus is the hottest planet due to its thick
atmosphere trapping heat through the greenhouse effect.
Venus: The Hottest Planet
Venus has an average
temperature of 450°C despite
not being closest to the Sun.
Its atmosphere is almost
entirely carbon dioxide, which
traps heat through the
greenhouse effect.
Earth: The Goldilocks Planet
Earth maintains an average
temperature of 15°C - perfect
for liquid water. Our
atmosphere contains the right
balance of gases to maintain
moderate temperatures.
Mercury: No Atmosphere
Despite being closest to the
Sun with temperatures
reaching 170°C, Mercury has
no atmosphere to trap heat,
resulting in extreme
temperature variations.
The greenhouse effect works differently than a plant greenhouse. In our atmosphere, gases like carbon
dioxide trap heat by absorbing radiation given off by Earth after being warmed by the Sun. A plant greenhouse
simply prevents warm air from escaping.
Page 5


Our Home: Earth,
a Unique Life
Sustaining Planet
Why Is Earth a Unique Planet?
While there are billions of planets in the universe,
Earth is the only one where life, as we know
today, exists and thrives in all its forms.
All life on Earth exists in just a very thin layer on
the surface of our planet. From the tallest
mountain to the deepest ocean trench, the crust
where all life exists is tiny compared to the size of
Earth.
If Earth were the size of an apple, the crust would
be as thin as the apple's skin - yet this delicate,
life-supporting layer is what makes Earth truly
special.
What Do the Planets of Our
Solar System Look Like?
Our solar system has eight planets orbiting the Sun in
nearly circular orbits. In order of increasing distance from
the Sun, they are Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, and Neptune.
Mercury, Venus, Earth, and Mars are relatively small and
rocky planets, while Jupiter, Saturn, Uranus, and Neptune
are large planets, mostly made of gases.
All planets get their energy from the Sun. Generally,
planets closer to the Sun are hotter, with one notable
exception: Venus is the hottest planet due to its thick
atmosphere trapping heat through the greenhouse effect.
Venus: The Hottest Planet
Venus has an average
temperature of 450°C despite
not being closest to the Sun.
Its atmosphere is almost
entirely carbon dioxide, which
traps heat through the
greenhouse effect.
Earth: The Goldilocks Planet
Earth maintains an average
temperature of 15°C - perfect
for liquid water. Our
atmosphere contains the right
balance of gases to maintain
moderate temperatures.
Mercury: No Atmosphere
Despite being closest to the
Sun with temperatures
reaching 170°C, Mercury has
no atmosphere to trap heat,
resulting in extreme
temperature variations.
The greenhouse effect works differently than a plant greenhouse. In our atmosphere, gases like carbon
dioxide trap heat by absorbing radiation given off by Earth after being warmed by the Sun. A plant greenhouse
simply prevents warm air from escaping.
What Makes the Earth Suitable for Life to Exist?
Too Close: Scorching Heat
If Earth orbited closer to the Sun, the
intense heat would cause all water to
evaporate into the atmosphere. This
extreme temperature would make it
impossible for life forms to survive.
Too Far: Icy Desolation
Moving farther from the Sun would
plunge Earth into extreme cold,
freezing all water into solid ice. Such
conditions would prevent any form of
life from thriving on its surface.
Just Right: The Goldilocks Zone
Earth's ideal distance from the Sun
places it within the "habitable zone,"
where temperatures are just right for
water to exist in its liquid form—a
fundamental requirement for life as we
know it.
Earth's nearly circular orbit further contributes to its suitability by maintaining a steady amount of sunlight and heat
throughout the year, preventing extreme seasonal variations that could destabilize life.