Important Facts For Prelims
Telescope in Cosmic World
- 25 Sep 2024
- 5 min read
Why in News?
An Extremely Large Telescope (ELT) is under construction atop the Cerro Armazones Mountain in the Atacama Desert in Chile.
What are Telescopes?
- About: A telescope is an instrument that astronomers use to observe faraway objects.
- It is a common misconception that telescopes are designed to make astronomical objects appear larger. Instead their primary function is to enhance the brightness of celestial objects, measured by their light-gathering power.
- The aperture size determines how much light can be gathered. A small reflecting telescope (0.07m aperture) gathers 118.5 times more light than the human eye.
- It is a common misconception that telescopes are designed to make astronomical objects appear larger. Instead their primary function is to enhance the brightness of celestial objects, measured by their light-gathering power.
- Types of Telescopes:
- Reflecting Telescope: It uses concave mirrors to focus incoming light, creating real, inverted, and smaller images. Most modern telescopes are reflectors, with parabolic mirrors to avoid image blurring.
- Refracting Telescope: A refracting telescope is a telescope that uses lenses and refraction to redirect light in order to magnify distant objects.
- The maximum practicable lens size in a refracting telescope is around 1 metre.
- The world’s largest refracting telescope is at Yerkes Observatory in the US, with a 1.02-m lens.
- Measuring Brightness: Apparent magnitude quantifies the brightness of celestial objects in a logarithmic scale.
- Lower values represent brighter objects (e.g., Sun at -26.78, Venus at -4.92), while higher values represent dimmer objects (e.g., Andromeda Galaxy at +3.44).
- Resolution of Telescopes: The human eye with 20/20 vision can see details as small as 60 arcseconds (1 arcsecond = 1/3600th of a degree).
- A toy telescope, with an optimal resolving power of about 1.47 arcseconds, can see over 40 times more detail than the human eye.
- Resolution defines the ability of telescopes to distinguish fine details between two close objects.
- Examples of Largest and Advanced Telescopes:
- Large Binocular Telescope (LBT): It is the largest telescope to date which has two 8.4-m-wide mirrors and an effective combined aperture of 11.9 m.
- It is located at the Mount Graham International Observatory in Arizona, US.
- Extremely Large Telescope (ELT): It is under construction atop the Cerro Armazones mountains in the Atacama Desert in Chile, as part of the European Southern Observatory.
- It has five mirrors and a combined aperture of 39.3 m.
- Subaru Telescope: It is an 8.2-m-wide Japanese telescope located at the Mauna Kea Observatory in Hawaii.
- International Liquid Mirror Telescope: It is India’s and Asia’s largest telescope located at Devasthal in Uttarakhand. It employs a 4-metre-diameter rotating mirror made up of a thin layer of liquid mercury.
- Large Binocular Telescope (LBT): It is the largest telescope to date which has two 8.4-m-wide mirrors and an effective combined aperture of 11.9 m.
Why are Telescopes Placed on Mountains?
- The Earth’s atmosphere causes turbulence, affecting the clarity of starlight and reducing telescope resolution.
- Higher altitudes like mountains offer less atmospheric disturbance.
- Space telescopes, like the Hubble Space Telescope, avoid these disturbances entirely, offering 10-times better resolution than ground-based telescopes.
- In recent years, Scientists create artificial stars with lasers to analyse atmospheric fluctuations. An advanced method, tomography, examines air segments to eliminate aberrations for clearer images.
Q. Consider the following phenomena: (2018)
- Light is affected by gravity.
- The Universe is constantly expanding.
- Matter warps its surrounding space-time.
Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media?
(a) 1 and 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: (d)
Q. In the context of modern scientific research, consider the following statements about ‘IceCube’, a particle detector located at South Pole, which was recently in the news: (2015)
- It is the world’s largest neutrino detector, encompassing a cubic kilometre of ice.
- It is a powerful telescope to search for dark matter.
- It is buried deep in the ice.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: (d)
