The Interstellar Visitor 3I/ATLAS Is Changing Color as It Nears the Sun
As 3I/ATLAS approaches its closest point to the Sun next month, astronomers watch a visitor from outside our solar system behave in real time. Its tail has grown longer, its coma has become more pronounced, and its glow has shifted from red to green. Some researchers even speculate that a surge in cyanide production could be part of this dramatic evolution — a clue that may redefine how we study interstellar visitors.
In This Article:
A Comet Born Outside the Solar System
Astronomers broadly believe 3I/ATLAS is a comet that originated beyond the solar system. The object’s rapid approach to the Sun has driven changes in its appearance: reddened dust scattering giving way to the production of small, optically bright icy grains, which alter the plume’s opacity. The ATLAS telescope team first spotted the object and its pathway, and scientists recently used a total lunar eclipse to image 3I/ATLAS under Namibia’s dark skies.
Green Glow and the Cyanide Hypothesis
The latest observations show the coma has shifted from red to green. Harvard astronomer Avi Loeb suggests this could be due to a steep rise in cyanide production, alongside nickel, as 3I/ATLAS approaches the Sun. Data from the ATLAS team describe an evolution from dust scattering toward the production of small, optically bright icy grains, changing the plume’s opacity.
An Odd Mass and an Unusual Orbit
Loeb notes that 3I/ATLAS is dominated by carbon dioxide — about 87 percent of its mass — a surprising feature for a small icy body. Its orbital path, which brings it unusually close to Mars, Jupiter, and Venus, is highly unusual and marks the object as an outlier among known icy rocks. While some have speculated about extraterrestrial artifacts, the accumulating observations support a highly unusual comet rather than an intelligent probe.
What This Means for Science — and Us
With the evidence still evolving, 3I/ATLAS remains an outlier that challenges our understanding of interstellar visitors. The balance of data favors a spectacularly unfamiliar comet, not an alien artifact, but the object will continue to push scientists to refine models of how such visitors form and evolve. The ongoing work by the ATLAS team and other space observatories will keep teaching us about the cosmos and remind us that our curiosity about distant worlds often leads to the most profound discoveries.
