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๐ฌ Think about it
Look up at dusk and you might spot a "star" gliding steadily across the sky. It's not a star — it's a satellite built by people. They help us talk, navigate, and forecast weather. Let's explore artificial satellites.
What are artificial satellites and how do they help us?
- The Moon is Earth's natural satellite; man-made ones also orbit Earth.
- Most orbit about 800 km up and take roughly 100 minutes per orbit.
- They help with communication, navigation, and weather monitoring.
- They also aid disaster management and scientific research.
Example:
ISRO's Cartosat satellites take images of Earth to improve maps and plan cities.
๐ Our scientific heritage
- ISRO's Cartosat satellites image Earth to improve maps and plan cities.
- The Bhuvan platform uses these images to show terrain and land use.
- AstroSat observes stars and other celestial objects.
- Other missions include Chandrayaan, Aditya L1, and Mangalyaan.
In this Activity, we will spot an artificial satellite moving across the night sky.
Materials needed
A clear open view of the sky, optionally binoculars or a satellite-tracking app, an accompanying adult.
Procedure
1. Just before sunrise or after sunset, go with an adult to a spot with a clear sky.
2. Look for a moving point of light with steady or flickering brightness.
3. Notice that it moves very fast across the sky.
4. Use the naked eye or binoculars to watch it.
5. Use an app or website to find which satellite is passing over.
2. Look for a moving point of light with steady or flickering brightness.
3. Notice that it moves very fast across the sky.
4. Use the naked eye or binoculars to watch it.
5. Use an app or website to find which satellite is passing over.
Observation
A satellite appears as a fast-moving point of light, unlike the fixed stars around it.
Explanation
Artificial satellites orbit the Earth quickly, so they appear to glide steadily across the sky, which helps us tell them apart from stars.
โ Summary
- Clear sky chosen
- Moving light spotted
- Watched carefully
- Satellite identified
๐ก A step further
- After their useful life, satellites and rocket parts become space debris.
- This debris crowds space and can collide with working satellites.
- Small debris burns up in the atmosphere as it falls.
- Countries are working together to remove dangerous debris.
๐ฌ Be a scientist
- Vikram Sarabhai (1919–1971) is the Father of the Indian Space programme.
- He researched space science and nuclear physics.
- He pioneered the launch of India's first artificial satellites.
- The Vikram Sarabhai Space Centre is named after him.
Important Points
- Artificial satellites are human-made and orbit the Earth.
- They help with communication, navigation, weather, and research.
- Old satellites become space debris that must be managed.
โ Test Yourself
-
What is Earth's natural satellite?
View Answer
The Moon. -
How high do most artificial satellites orbit?
View Answer
About 800 km above Earth's surface, taking roughly 100 minutes per orbit. -
Name two uses of artificial satellites.
View Answer
Any two of: communication, navigation, weather monitoring, disaster management, and scientific research. -
What is space debris?
View Answer
Old satellites and rocket parts left orbiting Earth, which can collide with working satellites. -
How can you tell a satellite from a star?
View Answer
A satellite moves fast and steadily across the sky, while stars appear fixed.
Important Definitions
- Artificial satellite — a human-made object launched to orbit the Earth for communication, navigation, and research.
- Natural satellite — a natural body orbiting a planet, such as the Moon orbiting Earth.
- Space debris — old satellites and rocket parts left orbiting Earth after their useful life.
๐ NCERT Question 11 — What is the purpose
What is the purpose of launching artificial satellites?
View Answer →
