Three years ago today, the James Webb Space Telescope (JWST) embarked on its journey to become humanity’s most advanced eye on the cosmos, Science Alert reports.
Decades in the making, the telescope has already delivered transformative insights into the universe in its short operational lifespan. From uncovering the mysteries of the early universe to probing exoplanets’ atmospheres, JWST has expanded the frontiers of astronomy and raised new questions.
One of JWST’s most groundbreaking contributions is its exploration of the early universe. Using its powerful infrared capabilities, the telescope has peered back to a time when the universe was only 300 million years old. It identified galaxies that defy expectations: massive, luminous, and distinctly blue, suggesting an absence of dust. These “blue monsters” challenge existing models of star formation and galaxy growth, leaving astronomers grappling with questions about their origins.
The early galaxies JWST has studied display unexpected chemical compositions. While the universe initially consisted of hydrogen, helium, and trace lithium, subsequent star formation produced heavier elements. Yet, these early galaxies show a surprising abundance of nitrogen and lower levels of other metals, hinting at previously unknown processes influencing chemical evolution.
JWST’s sensitivity has allowed astronomers to detect faint galaxies at the edge of cosmic visibility. These galaxies may have played a crucial role in ending the universe’s “dark ages,” a period after the Big Bang when light had not yet permeated space. The telescope has revealed a higher-than-expected number of these faint galaxies, whose emissions of energetic photons suggest they were instrumental in reionizing the universe.
Among JWST’s most enigmatic discoveries are “little red dots,” compact and puzzling objects in the early universe. Initially suspected to be ultra-dense galaxies, these objects have properties associated with both star populations and active galactic nuclei (regions around supermassive black holes). However, they lack expected X-ray emissions, adding to their mystery. Their study could reveal new insights into the co-evolution of stars and black holes.
In another surprising finding, JWST has identified massive “dead” galaxies from the universe’s early epochs. These relics of intense star formation, some as massive as the modern Milky Way, defy current models of galaxy formation. Scientists are now questioning whether to adjust these models or rethink the role of dark matter in the early universe.
