The images from Nasa’s James Webb Space Telescope allow us to trace the evolution of the universe and our galaxy and to understand our own origins – and possibly to find habitable planets around other stars
Comment: The James Webb Space Telescope (JWST) should be called the Just Wow Space Telescope. The new images it has delivered are of views of the universe we've seen before, but the clarity and detail are like a masterpiece restored to its full glory.
The telescope has been decades in the making with a huge international team of thousands of scientists and engineers working to dream, imagine, design, and build it. What we have seen shows they have achieved exactly what those first dreams reached for.
Zooming in on these images reveals many new details. There are multiple faint arcs, comprising many small bright dots, each of which is a galaxy. The detail and information are astounding. The images have texture – there is “lumpiness” in the clouds of gas in which new stars are forming.
The other real power of the telescope is all the observations are in infrared light, with longer wavelengths than red. It’s the type of light that warms your hands when you hold them up to a hot object. The JWST can look at the whole range of light at these wavelengths.
This is useful for two reasons. The wavelength of light a hot object emits depends on its temperature. For our sun, at about 6000C, this is in the middle of the optical spectrum, which equates to daylight. The JWST can also look at much cooler objects that are the same temperature as us – 37C – or colder. Now we can map out the temperature of different dust clouds or stellar winds to understand their dynamics.
The second reason concerns dust. These clouds of particles, about the size of cigarette smoke, scatter and obscure our usual view of distant stars. In the plane of our galaxy, clouds of dust block out most stars. However, dust doesn’t scatter infrared light so we can see many more stars in our galaxy and galaxies across the universe previously cloaked in dust.
But as great as the images in the infrared are, the truly spectacular advance is the spectra that have been obtained. One of the first images released is an accurate observation of water in the atmosphere of a hot Jupiter-sized exoplanet, WASP-96b – a planet orbiting another star. Though it's not habitable, it shows it is going to be much easier to study nearby exoplanets in our own galaxy.
The spectra transform our knowledge because the signature in the light of water is so clear. Previous studies have always had a significant uncertainty in the observations, but with these smaller errors no one can dispute the finding.
These smaller uncertainties also mean we’ll possibly be able to detect water on smaller planets, and maybe other molecules. This is the path to finding habitable planets around other stars, and maybe even indicators of life.
To me, more remarkable is the second spectra released of one of the tiny dots in the deep-field image. This is a spectrum of a galaxy at a redshift of 8.5. This means we can see the cosmos as it was 13.1 billion years ago, when the universe was only 600 million years old.
The second spectra reveal multiple emission lines of oxygen, neon, and hydrogen. The fact they are so clear and so bright will transform our understanding of how galaxies, and the composition of elements, evolve through cosmic history. We also know the stars in these galaxies evolve differently to those in our own galaxy, so it opens new areas to investigate.
All of this can be gleaned from a few new images. With more results coming of objects near and far, the JWST is going to reveal so many new aspects of our universe. The images allow us to trace the history of the evolution of the universe and our galaxy and to understand our own origins, which are part of the 13.7-billion-year journey of the universe.
