Science and Technology Class 9 Important Questions Chapter 18 Maharashtra Board

Observing Space : Telescopes

Short Questions

1. What is the difference between the sky and space?

• The sky is the view of space from Earth, while space is the vast universe beyond Earth’s atmosphere.

2. What is meant by space observation?

• It is studying stars, planets, and other objects in space using telescopes.

3. Who made the first telescope?

• Hans Lippershey made the first telescope in 1608.

4. Who used a telescope for space observations first?

• Galileo Galilei used a telescope for space observations in 1609.

5. What is the wavelength range of visible light?

• Visible light has wavelengths between 400 nm and 800 nm.

6. What is a refracting telescope?

• A telescope that uses lenses to bend light to form an image.

7. What is a reflecting telescope?

• A telescope that uses mirrors to reflect light to form an image.

8. Why are large mirrors used in reflecting telescopes?

• To collect more light and create brighter images.

9. What is chromatic aberration?

• It is the error in images caused by lenses splitting light into colors.

10. Name the two main types of reflecting telescopes.

• Newtonian and Cassegrain telescopes.

11. What does a radio telescope detect?

• It detects radio waves from space.

12. Where is the Giant Metrewave Radio Telescope (GMRT) located?

• It is located in Narayangaon near Pune.

13. How many dishes does the GMRT have?

• It has 30 dishes.

14. What is the largest optical telescope in India?

• The 3.6 m telescope at Aryabhatt Research Institute, Nainital.

15. Why are optical telescopes placed on mountains?

• To avoid city lights and atmospheric disturbances.

16. Name an optical telescope in space.

• The Hubble Telescope.

17. What does the Chandra telescope study?

• It studies X-rays from space objects.

18. When was ISRO established?

• ISRO was established in 1969.

19. What is the name of India’s space telescope launched in 2015?

• Astrosat.

20. What does the INSAT satellite series support?

• It supports telecommunication, TV broadcasting, and weather services.

Long Questions

1. Why do we need different types of telescopes to observe space?

• Different telescopes detect various forms of radiation, like visible light, X-rays, or radio waves, emitted by celestial objects. This helps scientists study different aspects of the universe comprehensively.

2. What are the difficulties in using ground-based optical telescopes?

• Ground-based telescopes face issues like light absorption by the atmosphere, turbulence causing image shaking, and city lights interfering with observations. These are overcome by placing telescopes on high mountains or in space.

3. How does a refracting telescope work?

• A refracting telescope uses an objective lens to collect and bend light from a distant object, focusing it to form an image. An eyepiece lens then magnifies this image for viewing.

4. What are the advantages of reflecting telescopes over refracting telescopes?

• Reflecting telescopes use mirrors, which are easier to make large and don’t cause chromatic aberration. They are also lighter and easier to manage than heavy lenses.

5. How does a radio telescope function?

• A radio telescope uses parabolic dishes to reflect radio waves from space to a focal point, where a receiver collects them. A computer then analyzes the data to create images of celestial objects.

6. Why are telescopes placed in space?

• Space telescopes avoid atmospheric absorption, turbulence, and light pollution, providing clearer and brighter images. They can also observe during the day and detect radiations blocked by the atmosphere.

7. What is the role of ISRO in space research?

• ISRO develops and launches satellites for communication, education, and resource management. It has advanced India’s space science, notably with missions like Astrosat.

8. How does the Hubble Telescope benefit space observation?

• Orbiting above Earth’s atmosphere, the Hubble Telescope captures clear, detailed images of distant stars and galaxies. It has contributed to major discoveries about the universe.

9. What makes the GMRT a unique telescope?

• The GMRT consists of 30 dishes acting as a single 25 km-wide dish, providing high-resolution data. It is a cost-effective, world-class facility for studying celestial phenomena.

10. What is the significance of the Astrosat satellite?

• Astrosat carries ultraviolet and X-ray telescopes, enabling Indian scientists to study various cosmic phenomena. Its unique multi-telescope design makes it a versatile tool for space research.