Comet 3I/ATLAS’ upcoming encounter with the sun could change it in big ways — Space photo of the week
QUICK FACTS
What is this : The interstellar comet 3I/ATLAS, which grows a tail
Where it is: The inner solar system on its way to Mars
When it was shared: September 4, 2025
Even if a bright comet, visible to the naked eye, crosses the Earth’s sky (cheers, Comet Lemmon!), the most famous object in the solar system today is hidden on the other side of the sun: the interstellar comet 3I/ATLAS.
We will miss our interstellar friend, but at least we will always have the photos. The image above, captured on August 27 by the Gemini South telescope, managed by the National Science Foundation, in Chile, is perhaps the clearest image we have so far. As 3I/ATLAS approaches the sun, radiation from our star heats the ice on the comet’s body (its core), causing gas and dust geysers to shoot outwards and form a luminous plume (a coma) around it. Radiation pressure from our star’s relentless solar wind pushes this material into a long, prominent tail oriented away from the sun.
As 3I/ATLAS reaches perihelion this week – less than 1.4 astronomical units, or 130 million miles (210 million kilometers) from the sun, according to NASA – it may start releasing gas in overdrive. When the comet becomes visible to telescopes again in early November, it could appear both larger and brighter than it did two months ago. Instruments on the ground, in orbit and even on the way to Jupiter will attract attention, making 3I/ATLAS an even bigger space celebrity as it moves away from our solar system forever.
Studying the interstellar comet with the full range of humanity’s astronomical instruments could reveal untold secrets about the far reaches of our galaxy and its mysterious history. In the meantime, all we can do is wait, feel the warmth of the sun on our faces, and know that a wealth of cosmic information lies just on the other side of our star.
For more sublime space images, check out our Archives of space photo of the week.
