Decades of hard work by thousands of scientists and engineers culminated in the launch of the James Webb Space Telescope (JWST) on December 25, 2021. Like other space observatories before it, such as Herschel and Gaia, JWST travelled to a location in space lying 1.5 million kilometres away, known as the second Lagrange Point, or L2. In the following months, the instruments cooled down, and following their testing and calibration, the first, highly anticipated images from JWST were released this week, heralding a new era in astronomy.
JWST is tuned to observe in the infrared, that is the region of the electromagnetic spectrum that lies beyond the red portion of visible light. While JWST is not the first infrared space telescope, it is by far the most sensitive. Moreover, it boasts the highest resolution in the infrared regime to date. But why infrared? A principal reason is that as the universe expands in size, light is shifted to redder wavelengths, and the more distant an object is, the larger this shift. This phenomenon is called redshift.
Let us consider a simple analogy by way of explanation. Imagine two ants standing on opposite ends of a ruler 10 centimetres long. Now imagine the ruler expanding to twice its size, with the ants not crawling anywhere themselves, but being carried along with the ruler as it stretches in size. Since the ruler is now 20 centimetres long, the ants end up being separated by 20 centimetres.
JWST is tuned to observe in the infrared, that is the region of the electromagnetic spectrum that lies beyond the red portion of visible light
The key point to take home is that although from each ant’s point of view, it seems as though the other ant is moving away from it, in reality, it is the ruler itself which expanded, carrying the ants away from each other. Now replace the ruler with space itself, and the ants with galaxies. As space expands, the galaxies end up ever more separated from each other.
The wavelength of light leaving each galaxy would also end up stretched as space expands. For very distant galaxies like the ones that JWST is observing, light originally emitted in the ultraviolet region of the spectrum (i.e. beyond the blue) is redshifted all the way to the infrared. And that is where JWST’s observing prowess comes in.
Moreover, infrared light also penetrates dust, thus allowing us to see past veils and tendrils in nebulae that appear opaque in visible light, revealing stars that lie beyond.
The first images are but a sneak peek at what lies ahead for JWST!
Joseph Caruana is an astrophysicist researching galaxy formation and evolution and galactic dynamics at the Department of Physics and Institute of Space Sciences at the University of Malta. He currently serves as vice-president of the Astronomical Society of Malta.
Josef Borg completed a PhD in Astronomy at the Institute of Space Sciences and Astronomy, University of Malta, and served as president of the Astronomical Society of Malta for three years. He is also Malta’s representative on the European Astrobiology Network Association (EANA) council.
Sound Bites
• Where did the first quasars come from?: New research is trying to shed light on the formation of the first supermassive black holes, weighing in at millions of solar masses, thus aiming to establish where the first quasars came from. Quasars, a shortened term for quasi-stellar radio sources, are active galactic nuclei which release significant amounts of radiation across the entire spectrum, in such intensity that they can be visible across billions of light years. They normally result from active supermassive black holes in the centres of galaxies which are actively accreting material.
• Successful launch of Capstone, the Lunar Gateway Pathfinder: The pathfinder will not arrive at the Moon before November however, and indeed, the Artemis 1 mission, which is slated for later this summer, might arrive at the Moon before Capstone itself. With the Lunar Gateway currently scheduled for construction commencement in 2024, Capstone will be given the task of entering a near-rectilinear lunar orbit, which will be the same orbit that the Lunar Gateway will eventually always use, and also test autonomous communications with the NASA Lunar Reconnaissance Orbiter.
For more soundbites, listen to Radio Mocha every Saturday at 7.30pm on Radju Malta and the following Monday at 9pm on Radju Malta 2 https://www.fb.com/RadioMochaMalta/.
DID YOU KNOW?
• JWST’s first year will incorporate 6000 hours’ worth of observations. Around 250 days’ worth of observations are in the pipeline for JWST, with many of these dedicated to small programmes, each taking no more than around 25 hours of imaging time on the telescope. Thousands of targets will be imaged, from distant galaxies to comets and exoplanets.
• JWST was first slated for 2007, but multiple delays resulted in the December 2021 launch. The delays were not without reason, however, and the wait seems to be bearing fruit, judging by the mission’s success thus far. The telescope is equipped with cameras boasting novel technologies on board, and the mission was so successful that even less propellant than required was used to position the telescope in L2 orbit, meaning that its mission lifetime has been more than doubled.
For more trivia, see: www.um.edu.mt/think.