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Earth and Space · Chapter 1: Introduction to Earth and Space Science
What is Earth and Space Science?
Earth and space science studies the Earth and everything beyond it. Learn the four spheres of the Earth system, key facts about our planet and why this science matters for Pakistan.
Key termRememberExampleWatch out
01Concept
Earth and space science is the study of the Earth (its rocks, water and air) and of everything beyond it in space, such as the Moon, Sun, planets and stars.
It tries to answer questions like: Why do earthquakes happen in northern Pakistan? Where does monsoon rain come from? Why does the Moon change shape? How far away are the stars?
The Earth as a system
Scientists think of the Earth as four connected parts, called spheres. A change in one sphere affects the others. Energy from the Sun drives most of these changes.
- Geosphere: the solid Earth: rocks, soil, mountains and the hot interior.
- Hydrosphere: all the water: oceans, rivers, lakes, groundwater and glaciers.
- Atmosphere: the layer of air around the Earth.
- Biosphere: all living things, including us.
Our planet in numbers
| Fact | Value (rounded) |
|---|---|
| Age of the Earth | about 4.6 billion years |
| Average radius | about 6,371 km |
| Surface covered by water | about 71% |
| Air | about 78% nitrogen and 21% oxygen |
| Distance from the Sun | about 150 million km |
| Time to spin once (one day) | about 24 hours |
| Time to go round the Sun (one year) | about 365¼ days |
Why it matters for Pakistan
- Earthquakes: northern Pakistan lies where two huge plates of the Earth's crust push together. The 2005 Kashmir earthquake killed more than 70,000 people in Pakistan.
- Floods: in the 2022 floods, about a third of the country was under water and more than 1,700 people died. Understanding monsoons and melting glaciers helps us prepare.
- Resources: coal in Thar, gas in Sui, and salt in Khewra were found by geologists.
- Space: Pakistan's satellites send TV signals and take photos of crops and floods.
02Real World Examples
Weather on your phone
The forecast you check before going out comes from meteorologists, who use satellite images and weather stations.
Building safely
In earthquake zones such as Islamabad and Quetta, buildings must follow building codes based on earthquake science.
Farming and water
Farmers along the Indus depend on water from glaciers and monsoon rain: a link between the hydrosphere and the biosphere.
Moon sighting
Astronomers can calculate the Moon's position and age, which helps when sighting the new crescent Moon for Islamic months.
03Practice Questions
Try to answer in your own words first, then open the model answer.
Short questions
Q1.What is Earth and space science?Show answer
Answer
Earth and space science is the study of the Earth (its rocks, water and air) and of everything beyond it in space, such as the Moon, Sun, planets and stars.
Q2.Name the four spheres of the Earth system with one example of each.Show answer
Answer
- Geosphere: rocks and mountains.
- Hydrosphere: oceans and rivers.
- Atmosphere: the air.
- Biosphere: plants, animals and people.
Q3.Give an example to show that the Earth's spheres affect each other.Show answer
Answer
The monsoon: the Sun heats the land and sea, winds carry moist air from the sea, rain falls on land, and the water is used by plants, animals and people. So the geosphere, hydrosphere, atmosphere and biosphere are all involved.
Q4.Why is Earth and space science important for Pakistan? Give two reasons.Show answer
Answer
- Pakistan faces earthquakes and floods; understanding them helps people prepare and build safely.
- It helps find resources such as coal, gas and minerals.
Long questions
Q5.Describe the Earth as a system of four spheres. How does the Sun affect them?Show answer
Answer
- Geosphere: the solid Earth: rocks, soil and the interior.
- Hydrosphere: all water: oceans, rivers, groundwater and glaciers.
- Atmosphere: the air around the Earth.
- Biosphere: all living things.
The Sun's energy heats the land, sea and air. This drives winds, evaporation, rain and ocean currents, and gives plants the light they need to make food. A change in one sphere affects the others.