On July 1, scientists made a unique discovery near Jupiter’s orbit: an object with an unusual trajectory that didn’t follow the typical path around the sun like most asteroids or comets. This object, known as 3I/ATLAS or C/2025 N1 (ATLAS), turned out to be an interstellar visitor. Recently, astronomers used the U.S. National Science Foundation’s Gemini North telescope in Hawaii to capture the first detailed image of this cosmic wanderer.
According to Martin Still, the NSF program director for the International Gemini Observatory, researchers anticipate gathering a wealth of new information and insights as the object warms up in sunlight before resuming its journey through the vastness of space. The comet will remain observable through large telescopes until September, after which it will disappear in the brightness of the sun.
Paul Wiegert, an astronomy professor at Western University, expressed excitement about studying this newfound interstellar visitor, only the third of its kind ever detected. Investigating comets and asteroids is essential as they offer insights into the early formation of our solar system. Analyzing objects from outside our immediate cosmic vicinity could provide valuable knowledge about other star systems.
Initial observations indicate that the comet has a diameter of about 20 kilometers, significantly larger than the two previous interstellar comets that traversed our solar system. ‘Oumuamua, the first comet, had a diameter of 200 meters, while 2I/Borisov, the second, measured one kilometer across. The size of 3I/ATLAS presents a unique opportunity for astronomers to study it more effectively, especially as it approaches Earth. Despite making a close pass in December, the comet poses no threat to our planet.
A recent study presented by Matthew Hopkins at the Royal Astronomical Society’s National Astronomy Meeting 2025 suggests that this interstellar visitor could be the oldest comet ever observed. Hopkins estimates the comet’s age to be around seven billion years, originating from a region of our galaxy housing ancient stars. This makes the comet significantly older than our solar system, which is approximately 4.5 billion years old. Notably, the comet was traveling at a speed of about 61 kilometers per second when first detected.
Astronomers can determine the origin of comets or asteroids by analyzing their orbital eccentricity, which indicates how elongated their paths are. An eccentricity of 0 signifies a perfectly circular orbit, while a value greater than one indicates a non-circular orbit. In the case of 3I/ATLAS, its eccentricity of 6.2 revealed its extraterrestrial origin. Comparatively, ‘Oumuamua had an eccentricity of 1.2, and 2I/Borisov’s eccentricity was 3.6.
Presently, the comet remains within Jupiter’s orbit, approximately 465 million kilometers from Earth. Its closest approach to our planet is expected on December 19 at a distance of roughly 270 million kilometers. On October 30, it will reach its nearest point to the sun at a distance of 210 million kilometers, just inside the orbit of Mars.
Despite early discoveries about this intriguing visitor, astronomers anticipate uncovering more details in the future. Paul Wiegert noted that 3I/ATLAS appears similar to comets from our solar system, primarily composed of ice that has been frozen for billions of years as it journeyed through the galaxy. As the comet starts to vaporize gently in the sun’s light, it becomes visible with a tail, as shown in the images. However, uncertainties remain about whether it resembles our solar system’s comets or represents something entirely distinct.