‘The JWST images can help us cherish Earth’s present’

Rahul Kannan is a Fellow at Harvard University’s Institute for Theory and Computation. He tells Times Evoke about how the JWST spotlights Earth:

I work mainly on the formation and evolution of galaxies over cosmic time. Galaxies are huge collections of stars, dust and gas which are gravitating themselves and which come in different shapes, sizes and properties. Using computer simulations, I explore how such galaxies form.



From my perspective, with the James Webb technology, the most amazing thing is that you can see galaxies which formed 11 to 13 billion years ago — you are therefore starting to see the very beginning structures of the universe itself. This kind of travel through time, which helps us understand the evolution of space, is extremely exciting. With its infrared technology, this telescope has gone further back in time than we have ever been before. The light from these early galaxies gets stretched due to the expansion of the universe — even optical and ultraviolet light get stretched into infrared. Now, because James Webb is very sensitive in this range, we can see galaxies that are extremely far away, from earlier and farther back in time.

HOW STEPHAN’S QUINTET PLAYS: The JWST has captured Stephan’s Quintet, a group of five galaxies, showing sparkling clusters of young stars, starburst regions and long tails of gas, dust and stars being pulled about from galaxies due to gravitational interactions. Photo Courtesy: NASA, ESA, CSA & STSc


Also, for the first time, we are able to get high-resolution images of these galaxies, which tell us how many stars are being formed, the size and stellar mass of these galaxies, the amount of gas and dust therein, etc. I use computer simulations to make predictions for these properties — but we can now match these with JWST data and evaluate how good our simulations of the early universe are.



For many people, studying space can seem like a remote exercise, distant from everyday life. However, for many, it also evokes deep curiosity. If you simply look at the night sky, you see so many different stars. With a small telescope, you can see nebulae and other cosmic phenomenon. The question astronomy has always sought to answer is, what exactly is out there and where do we come from? Our own planetary system is the solar system, located in the Milky Way galaxy. Using such space data, we can understand how the Milky Way and its planets — and life itself — formed. We need to understand how we got here in the first place and these are interconnected questions in that exploration.

Astronomical images like these also help us cherish our present — and hopefully save our future. Once you start to understand just how vast the universe is, with so many different galaxies, planets and stars, you appreciate that we human beings are not the centre of everything — we are just one small species, in one corner of one average galaxy. Yet, Earth is also a very precious resource, the only planet which is known to have life. Preserving this resource to maintain life is extremely important. Seeing these images gives us two different understandings simultaneously — we get a sense of Earth’s smallness and its insignificance, as well as its utter rarity. This gives us a very different view of our existence. Suddenly, small, short-term things don’t really matter so much. These images help us understand that the big things we should actually invest our energies in are solving challenges like climate change, which is now impacting Earth itself.