It took 30 years to build JWST, but in a short span, this telescope has already revolutionised our view of the cosmos
Melbourne: We witnessed the nail-biting launch of the James Webb Space Telescope (JWST), the largest and most powerful telescope humans have ever sent into space. Now, three years later, JWST has pushed the boundary of how far we can look into the universe to find the first stars and galaxies.
It took 30 years to build, but in a short span, JWST has already revolutionised our view of the cosmos. It’s explored our own Solar System, studied the atmospheres of distant planets in search of signs of life, and probed the farthest depths to find the very first stars and galaxies formed in the universe.
Eerie blue monsters
When galaxies grow, their stars explode, creating dust. The bigger the galaxy, the more dust it has. This dust makes galaxies appear red because it absorbs the blue light. But here’s the catch: JWST has shown these first galaxies to be shockingly bright, massive and very blue, with no sign of any dust. That’s a real puzzle.
Unusual chemistry in early galaxies
JWST has discovered that early galaxies contained a significant amount of nitrogen along with hydrogen and helium, far more than what we observe in our Sun, while most other metals are present in lower quantities. JWST has shown how stars that drive the chemical evolution of galaxies are still incomplete, meaning we still don’t fully understand the conditions that led to our existence. The discovery suggests these small galaxies may have played a crucial role in ending the cosmic “dark ages” not long after the Big Bang.
Little red dots
The very first images of JWST resulted in another dramatic, unexpected discovery. The early universe is inhabited by an abundance of “little red dots”: extremely compact red colour sources of unknown origin. Initially, they were thought to be massive super-dense galaxies that shouldn’t be possible, but detailed observations in the past year have revealed a combination of deeply puzzling and contradictory properties.
Giant corpses
JWST has also found corpses: galaxies in the early universe that are relics of intense star formation at cosmic dawn. Hubble and ground-based telescopes had found these corpses, but only JWST had the power to dissect their light to reveal how long they’d been dead. It has uncovered some extremely massive galaxies formed in the first 700 million years of cosmic history, but our galaxy formation models can’t explain these objects.
So, what’s next for JWST?
Just within its first steps, the telescope has revealed many shortcomings of our current models of the universe. While we are refining our models to account for the updates JWST has brought us, we are most excited about the unknown unknowns. The mysterious red dots were hiding from our view. What else is lingering in the depths of cosmos? JWST will soon tell us.
