Explained: NASA’s flagship telescope, and its successor

What is the News?

NASA has announced the launch of the James Webb Space Telescope(JWST) on December 24. It will succeed the Hubble Space Telescope, NASA’s flagship telescope that has been in service for more than three decades now.

What are the differences between James Webb Telescope and Hubble Space Telescope?

Wavelength: Hubble can observe mainly in the ultraviolet and visible parts of the spectrum. On the other hand, Webb will primarily study the universe in the infrared spectrum.

Note: Infrared observations are important because light at this wavelength can penetrate the dust that shrouds newly formed stars and planets and make them visible.

Size: Webb telescope will cover more than ~15 times the field of view covered by the Hubble telescope.

Orbit: Hubble orbits the Earth at an altitude of ~570 km. Webb will not orbit the Earth, instead it will sit at the Earth-Sun L2 Lagrange point, 1.5 million km away. This means that Webb will orbit the Sun along with the Earth, but will stay fixed at the same spot in relation to the Earth and the Sun.

Moreover, at the L2 point, Webb’s solar shield will block the light from the Sun, Earth, and Moon which will help it stay cool. This is significant for an infrared telescope.

Distance: Hubble can see the equivalent of “toddler galaxies”, On the other hand, Webb will be able to see “baby galaxies”. This is because Webb is an infrared telescope, and can see distant objects which are very dim at visible wavelengths of light.

Must read: James Webb Telescope: How Webb will take us to the universe’s first galaxies

Source: This post is based on the article ‘Explained: NASA’s flagship telescope, and its successor published in Indian Express on 22nd Dec 2021.

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