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Earth and Space · Chapter 1: Introduction to Earth and Space Science
Tools: Telescopes, Satellites and Seismometers
How telescopes, satellites and seismometers work, with diagrams, types of each, Pakistani satellites such as PRSS-1 and PakSat, and everyday weather instruments.
Key termRememberExampleWatch out
01Concept
We cannot visit the centre of the Earth or travel to the stars, so scientists use instruments that collect information from far away. The three most important are telescopes, satellites and seismometers.
1. Telescopes
A telescope collects light (or other radiation) from distant objects and makes them look bigger and brighter.
| Type | How it works | Example |
|---|---|---|
| Refracting telescope | Uses lenses to bend light | Early telescopes, school telescopes |
| Reflecting telescope | Uses a curved mirror to collect light; can be made much bigger | Most large research telescopes |
| Radio telescope | A large dish that collects radio waves from space | Studies of galaxies and pulsars |
| Space telescope | Orbits above the atmosphere, so the air does not blur or block the view | Hubble (1990), James Webb (2021) |
2. Satellites
A satellite is an object that moves in orbit around a planet. The Moon is a natural satellite; the ones we launch are artificial satellites.
| Type of satellite | Job | Example |
|---|---|---|
| Communication | Carry TV, phone and internet signals | PakSat-1R (2011), PakSat-MM1 (2024) |
| Earth observation | Photograph the land to watch crops, floods and cities | PRSS-1 (2018) |
| Weather | Watch clouds, storms and temperatures | Images used in monsoon and cyclone forecasts |
| Navigation | Tell you your exact position | GPS, and China's BeiDou system |
3. Seismometers
A seismometer detects and records the shaking of the ground. The record it makes is called a seismogram.
By comparing the times the shaking reaches different seismometers, scientists can find where an earthquake started and how strong it was. Pakistan's earthquake monitoring is done by the Pakistan Meteorological Department.
Other everyday instruments
| Instrument | Measures |
|---|---|
| Thermometer | Temperature |
| Barometer | Air pressure |
| Rain gauge | Amount of rain |
| Anemometer | Wind speed |
| Weather balloon (radiosonde) | Temperature, pressure and humidity high in the air |
| Weather radar | Where rain is falling and how heavily |
02Real World Examples
Flood maps
In the 2022 floods, satellite images showed exactly which villages and fields were under water, so help could be sent quickly.
Ride-hailing apps
Apps like ride-hailing and food delivery use navigation satellites to find you.
Live cricket on TV
Matches played abroad reach your TV through communication satellites.
Earthquake alerts
Within minutes of an earthquake, seismometer networks report its location and magnitude on the news.
03Practice Questions
Try to answer in your own words first, then open the model answer.
Short questions
Q1.What is a telescope? Name two types.Show answer
Answer
A telescope is an instrument that collects light from distant objects and makes them look bigger and brighter.
- Refracting telescope: uses lenses.
- Reflecting telescope: uses a curved mirror.
Q2.Why are some telescopes placed in space?Show answer
Answer
Because the atmosphere blurs and blocks some light from space. A telescope in orbit, such as Hubble, gets a much clearer view.
Q3.Differentiate between a geostationary orbit and a low Earth orbit.Show answer
Answer
| Geostationary orbit | Low Earth orbit |
|---|---|
| About 36,000 km above the equator | A few hundred km up |
| One orbit takes 24 hours, so it stays over one place | One orbit takes about 1.5 hours |
| Communication and TV satellites | Earth-observation satellites |
Q4.How does a seismometer work?Show answer
Answer
Its frame is fixed to the ground and shakes during an earthquake, but a heavy mass stays almost still because of inertia. A pen attached to the mass draws the movement on a rotating drum, making a seismogram.
Long questions
Q5.Describe the uses of telescopes, satellites and seismometers in Earth and space science.Show answer
Answer
- Telescopes collect light or radio waves to study the Moon, planets, stars and galaxies. Space telescopes like Hubble and James Webb avoid the blurring of the atmosphere.
- Satellites carry TV and phone signals (PakSat-1R), photograph the Earth (PRSS-1), watch the weather, and give positions (GPS).
- Seismometers record ground shaking, so scientists can find where an earthquake started and how strong it was.