Explained: What Is James Webb Telescope And How Different Is It From Hubble Telescope

The James Webb Space Telescope, often known as Webb or JWST, is a huge, space-based observatory that is tailored for infrared wavelengths. It is a successor of the Hubble Space Telescope and has a wider wavelength range and increased sensitivity than the Hubble Telescope.

Webb can scan further back in time to identify the earliest galaxies that formed in the early Universe, as well as gaze inside dust clouds where stars and planetary systems are developing today, thanks to the longer wavelengths.

A general description

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The James Webb Telescope was launched into space on December 25, 2021 using the Ariane 5 ECA rocket. The telescope orbits 1.5 million km from earth at L2 Lagrange point. It weighs around 6200 kg (approx) and has 18 gold-plated hexagonal mirrors, collectively 6.5 m in diameter having the wavelength coverage of 0.6 to 28.5 microns in the IR spectrum.

Its operating temperature is under 50 K and is protected by a five-layer deployable sunshield that spans across 69.5 ¡Á46.5 (ft) in dimensions. The construction of the James Webb Space Telescope involves 14 countries: Austria, Belgium, Canada, Denmark, France, Germany, Ireland, Italy, the Netherlands, Spain, Sweden, Switzerland, the United Kingdom and the United States.

Why is it called the James Webb Telescope?

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Initially, the telescope was called the Next Generation Space Telescope (NGST) but was later renamed as the James Webb Telescope in honour of James E. Webb, NASA¡¯s second administrator and the man responsible for putting humans in space through the Apollo missions.

The former name was apt in its description of the new telescope as a new technological advancement than its predecessor, the Hubble Space Telescope given its features like deployable mirror, lighter weight and range.

A brief comparison between the Hubble Telescope and the Webb Telescope:

It is often speculated that Webb is a replacement for the Hubble but in reality, it is more of a successor than a replacement as they differ in many aspects. The Hubble Space Telescope primarily operates on the UV spectrum with a small addition of 0.8 to 2.5 micron in the infrared (IR) spectrum.

But as the distance increases, objects are redshifted and their light shifts from UV to infrared, where the Webb focuses on with a wavelength coverage of 0.6 to 28 micrometers. Webb¡¯s primary mirror is larger (6.5 m in diameter) than Hubble¡¯s mirror (2.4 m in diameter) which means the former can see farther back in time.

Another difference between the two is that the Hubble Telescope orbits the earth whereas the Webb orbits the sun at the sun-earth L2 (second) Lagrange point.

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Recently, the James Webb Telescope completed its final stage of telescope alignment and is ready for science instrument commissioning. The science instrument commissioning process involves pointing each instrument at different parts of the sky, varying the amount of solar radiation that reaches the observatory and allowing engineers to ensure thermal stability as targets change.

This will take around two months of thorough calibrations and the last set of setup procedures before the telescope begins science observations A test image taken by Webb of a region of the Large Magellanic Cloud was compared to a previous image taken by the Spitzer Space Telescope of the same location.

Webb's ability to see the infrared sky with greater clarity is demonstrated in this comparison. This further emphasizes the possibilities of future discoveries through this telescope.

References:

¡°Comparison: Webb vs Hubble Telescope - Webb/NASA.¡± James Webb Space Telescope. Accessed 15 May 2022.

¡°FAQ Full General Public Webb Telescope/NASA.¡± James Webb Space Telescope. Accessed 15 May 2022.

Hughes, Alex. ¡°James Webb Space Telescope: launch date, size and mission goals.¡± BBC Science Focus Magazine, 5 May 2022. Accessed 15 May 2022.

¡°James Webb Telescope is Fully Aligned and Delivering Sharp Photos.¡± PetaPixel, 28 April 2022. Accessed 15 May 2022.

¡°Key Facts - Webb/NASA.¡± James Webb Space Telescope. Accessed 15 May 2022.