Why I am excited about first images from James Webb Space Telescope

The long-awaited giant leap in the field of astronomy is right around the corner as the $10 billion observatory, located nearly 15,00,000 kilometres away from home, is about to take us beyond the world of imagination and into the realm of possibilities that once were just imaginations.

The first science image captured by the world’s most powerful observatory will drop on Tuesday.

Although Masa has been tightly guarded about the target of this first observation, it has been dropping teasers over the last six months as the telescope came about in the darkness of space after being launched late last year. While the target remains a secret, there are indications that the data release will contain the “deepest views of the Universe ever taken, and spectra obtained from an exoplanet atmosphere.”

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The images released in the last few months are so stunning that they apparently brought Thomas Zarbuchen, who is Associate Administrator for Nasa’s Science Mission Directorate (SMD), to tears!

Operating at infrared wavelengths that are not accessible from Earth, Webb is the only current facility capable of delivering unprecedented views of the cosmos at these wavelengths, which are expected to contain light from some of the first galaxies to have formed in the Universe as well as potentially life-harbouring signatures in exoplanetary atmospheres.

The primary data products delivered by JWST will be images and spectra. Spectra contains highly complementary information regarding emission and absorption from atoms and molecules that are vital to understand. For example, the chemical composition of stars and gas in distant galaxies and the atmospheres of planets orbiting other stars.

A spectrum is obtained by splitting light arriving from astrophysical sources over a range of wavelengths. Whereas an image gives us information about the total brightness of an object in the photometric filter using which the object is observed, a spectrum gives us the differential brightness of that object across the entire wavelength range covered in that filter.

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For studies of the formation and evolution of the most distant galaxies in the Universe, the early observing plan with JWST is to target parts of the sky that have already been observed with the Hubble Space Telescope over the last couple of decades. This will enable JWST observations to instantly build upon the incredible legacy value of existing Hubble data, providing complementary observations at infrared wavelengths that have not previously been possible. Doing this would allow spectroscopic follow-up of distant, extremely faint galaxies that have already been identified in Hubble imaging, as well as detecting even more distant galaxies that Hubble is not capable of finding, as light from the most distant objects in the Universe is “redshifted” into infrared wavelengths.

What’s certain is that whatever Nasa chooses to show in its JWST First Images event, these views of the cosmos will be humanity’s first ever foray into previously uncharted territory.

This event is a historic moment, not just for astronomers like me, but for humanity in general, reminding us once again that the sky under which we live is the same for all creatures, and that we are merely a speck of dust in the incredible vastness of the Universe that has billions of stars, trillions of galaxies, and quadrillions of possibilities.

(Dr Aayush Saxena is a Postdoctoral Research Fellow in Astrophysics at University College London. His research aims to understand the formation and evolution of stars and supermassive black holes)

Also Read: | Imagine seeing Milky Way in 2000 infrared colours. James Webb Telescope is about to do it

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