An unusual visitor from deep space is helping scientists learn more about what the universe was like billions of years before our solar system even existed.
The object, called 3I/Atlas, is an interstellar comet. Unlike the comets that travel around our Sun, this one came from another star system far beyond our solar system.
When it was first discovered last year, some people even wondered if it could be an alien spacecraft. However, observations by NASA quickly showed that it is a natural comet.
Although it is not an alien spaceship, 3I/Atlas is still an extraordinary discovery. Using the powerful James Webb Space Telescope (JWST), scientists studied the comet’s chemical makeup.
The results suggest that it formed about 10 to 12 billion years ago, making it far older than our own solar system, which formed about 4.5 billion years ago.
According to physicist Jacqueline McCleary from Northeastern University, studying this comet is like examining something from a completely different family tree.
The basic chemical ingredients are familiar, but they have developed under very different conditions.
One of the biggest discoveries was that the comet contains about 30 times more deuterium than comets found in our solar system.
Deuterium is a heavier form of hydrogen because it contains an extra particle called a neutron. When water is made with deuterium instead of normal hydrogen, it is known as “heavy water.”
This large amount of heavy water tells scientists that the comet formed in an extremely cold environment. Unlike our solar system, where heat has changed many materials over billions of years, the comet’s home system appears to have stayed cold enough to preserve its original chemistry.
Scientists also found very small amounts of carbon-13, a heavier form of carbon. This is another important clue about the comet’s age. As stars live and die, they create heavier elements and spread them into space. Younger star systems usually contain more of these heavy elements because they formed after many generations of stars.
Since 3I/Atlas has very little carbon-13, researchers believe it formed before many stars had completed their life cycles. This makes it one of the oldest objects ever studied directly.
NASA believes the comet formed during a period known as the universe’s “cosmic noon.” This happened about 2 to 3 billion years after the Big Bang, when stars were forming faster than at any other time in cosmic history. During this period, the universe was filled with brilliant young stars and was much brighter than it is today.
Even with advanced telescopes like JWST, scientists still know surprisingly little about this important chapter in the universe’s history. Questions remain about how the first galaxies, stars and planets formed, and why the universe is producing far fewer new stars today. Objects like 3I/Atlas provide valuable clues because they have preserved chemical records from that ancient time.
The comet may also help scientists understand how common life might be in the universe. Life on Earth depends on water and elements such as carbon and oxygen. Since 3I/Atlas appears to have formed in an environment with relatively few of these important building blocks, it suggests that conditions suitable for life may have been much rarer in the early universe.
Researchers say every new observation of this ancient traveler reminds us that our own solar system may be more unusual than we once thought.
By studying visitors from distant star systems, scientists are slowly uncovering the history of the universe—and learning more about how special our own cosmic home may be.
