krit.club logo

Our Home: Earth, a Unique Life Sustaining Planet - Why Is Earth a Unique Planet?

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Earth is known as the 'Blue Planet' because approximately 71%71\% of its surface is covered with water, while the remaining 29%29\% consists of landmasses.

•

The 'Goldilocks Zone' or Habitable Zone refers to the orbital region around the Sun where the temperature is just right—not too hot and not too cold—to allow liquid water to exist on the surface.

•

Earth's atmosphere is a unique mixture of gases: Nitrogen (78%78\%), Oxygen (21%21\%), and trace gases like Carbon Dioxide (0.03%0.03\%), Argon, and water vapor.

•

The Ozone layer (O3O_3), located in the stratosphere, acts as a shield by absorbing 97%−99%97\%-99\% of the Sun's medium-frequency ultraviolet (UVUV) light, which would otherwise damage life forms.

•

The Greenhouse Effect, caused by gases like CO2CO_2 and CH4CH_4, traps heat in the atmosphere, maintaining an average global temperature of approximately 15∘C15^\circ C, which is essential for survival.

•

Earth possesses a strong magnetic field (magnetosphere) that protects the planet from the 'Solar Wind'—a stream of charged particles emitted by the Sun.

•

The Hydrological Cycle (Water Cycle) ensures the continuous movement of water between the Earth's surface and the atmosphere, supporting various ecosystems.

📐Formulae

6CO2+6H2O→Sunlight, ChlorophyllC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{Sunlight, Chlorophyll}} C_6H_{12}O_6 + 6O_2

C6H12O6+6O2→6CO2+6H2O+EnergyC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}

Earth’s Surface Area Ratio=7129≈2.45:1 (Water to Land)\text{Earth's Surface Area Ratio} = \frac{71}{29} \approx 2.45:1 \text{ (Water to Land)}

💡Examples

Problem 1:

Explain why Earth is considered a unique planet in terms of its atmospheric composition compared to its neighbors, Venus and Mars.

Solution:

Earth's atmosphere contains 21%21\% Oxygen (O2O_2), which is vital for aerobic respiration. In contrast, the atmospheres of Venus and Mars are dominated by Carbon Dioxide (CO2CO_2), exceeding 95%95\%. Furthermore, Earth has an Ozone layer (O3O_3) and a moderate Greenhouse effect, whereas Venus has an extreme Greenhouse effect (460∘C460^\circ C) and Mars has an extremely thin atmosphere that cannot retain heat.

Explanation:

Life requires a specific balance of gases for biological processes and temperature regulation, which is only found on Earth.

Problem 2:

Calculate the approximate area covered by water if the total surface area of the Earth is 510,072,000 km2510,072,000 \text{ km}^2.

Solution:

Area of Water=71100×510,072,000\text{Area of Water} = \frac{71}{100} \times 510,072,000 Area of Water≈362,151,120 km2\text{Area of Water} \approx 362,151,120 \text{ km}^2

Explanation:

Since 71%71\% of the Earth's surface is water (Hydrosphere), we multiply the total area by 0.710.71 to find the aqueous coverage.