The James Webb Space Telescope: Redefining Our View of the Universe

The James Webb Space Telescope (JWST), launched into orbit just two years ago, has already begun to redefine our view of the primordial Universe.

Marvel at the extraordinary collection of images captured by the James Webb Telescope on this page—from the farthest reaches of the Universe to familiar objects closer to home within our Solar System.

It’s incredible to think that imaging isn’t actually the telescope’s main workload. More than 70% of its time is spent on spectroscopy, which involves sampling the light of objects and splitting it into a rainbow of colors. This allows scientists to retrieve important information about the chemistry, temperature, density, and velocity of the targets under study.

“You could think of the James Webb as a giant spectrometer that occasionally takes beautiful photos,” jokes Eric Smith, a scientist on the James Webb research program at NASA.

Even without fully utilizing its capabilities, the James Webb Telescope has been peering deeply into the cosmos to reveal galaxies as they were 13.5 billion years ago. Many of these cosmic structures are brighter, more massive, and more mature than scientists previously thought possible shortly after the Big Bang, which occurred 13.8 billion years ago.

“We certainly thought we would see diffuse bubbles of stars. But we have observed fully formed galaxies, complete with perfect spiral arms,” assesses Professor Gillian Wright, director of the UK Astronomy Technology Centre at BBC News.

“Theorists are working to understand how these mature structures arose so early in the Universe. In this sense, the Webb is truly changing scientific thinking,” she adds.

It’s not just the efficiency of the early galaxies in forming their stars that has surprised scientists. The size of the black holes at the center of galaxies has also amazed experts.

There is a “monster” at the center of our Milky Way that has four billion times the mass of the Sun. One theory suggests that these giants are created over time by accumulating many smaller black holes produced as remnants of exploding stars (supernovas).

“But preliminary evidence from the JWST indicates that some of these early [black holes] giants may have completely bypassed that stellar stage,” points out researcher Adam Carnall from the University of Edinburgh in Scotland.

“There is a scenario in which huge clouds of gas in the primordial Universe could have violently collapsed, transforming into black holes.”

When the James Webb Telescope was launched on Christmas Day in 2021, it was thought to have ten years of operations ahead. This is because the device needs fuel to remain active at 1.5 million km from Earth.

But its flight towards the orbit of an Ariane rocket, launched by European researchers, was so precise that it has fuel reserves for the next 20 years—if not more.

This means that, instead of accelerating observations, astronomers can afford to adopt a more strategic approach to working with the telescope.

“We thought we would be ‘rushing the recipe’ [if observations were accelerated], and we don’t need to do that anymore,” evaluates Smith from NASA.

One activity that will certainly accelerate from now on is the practice of making “deep fields”—lengthy observations for specific areas of the sky, which will allow the telescope to track the light of fainter, more distant galaxies.

This is how the telescope will likely detect the first galaxies and possibly even some of the first stars that shone in the Universe.

The famous Hubble Telescope spent many days just looking at a single corner of the cosmos.

“I don’t think we will need the hundreds of hours of exposure that Hubble required, but I think we will need multiple deep fields,” foresees researcher Emma Curtis-Lake from the University of Hertfordshire in the UK.

“We’ve already had quite long exposures with the JWST and we’ve seen a lot of variation. So we can’t just put everything in a tiny area because there’s no guarantee we’ll find something super exciting there,” she explains.

Astronomer Massimo Stiavelli from the Space Telescope Science Institute dreams of locating a star that is primordial—meaning it has the signature of the original chemistry that emerged from the Big Bang and has not been polluted with later-forged elements in cosmic history.

“We will need to see them as supernovas when they explode,” explains the head of the Webb mission office.

“To do that, we will need to start looking at the same spots year after year, to detect them before and shortly after they explode. They are extremely rare and we will need a lot of luck.”