Race against time: Two comets captured 'racing' side by side over Reunion island

Comets C/2025 K1 ATLAS (left) and C/2025 R2 SWAN (right) were seen racing against each other on Reunion Island. (Image: X/@LucPerrot_Photo)

An astrophotographer from Réunion Island has been able to capture two comets at one time. C/2025 K1 ATLAS and C/2025 R2 SWAN were seen passing across the evening sky. From Earth’s surface view, the astronomical duo appears as if they are “racing,” providing a stunning visual spectacle for astronomers as well as photographers.

While the image shows the comets close to each other, their actual orbits are very dissimilar. C/2025 K1 ATLAS is an interstellar visitor, travelling on a hyperbolic orbit from outside the solar system. On the other hand, C/2025 R2 SWAN is an established solar system comet that orbits the Sun along a more conventional course. The apparent alignment is purely a matter of perspective, so the phenomenon itself is very rare.

The dark, clear skies of Réunion Island provided ideal conditions for photographing this short moment. Good timing and skill of the photographer enabled both comets to be perfectly framed by their glowing tails and icy nuclei. These kinds of pictures impress but also contribute to further observations of cometary activity and movement.

Comets like ATLAS from outside the Solar System are of extraordinary scientific interest. They contain foreign matter from other stellar systems that offers an extraordinary view of chemistry and type of dust. By observing such comets, the scientists could get information about their origins as well as diversity of extraterrestrial planetary systems.

Such occurrences also drive home the reality that the night-time sky is a changing canvas of celestial motion. The researchers are encouraged to monitor upcoming cometary events that are brief but offer the rare experience of witnessing the glory of the universe in action. When cameras and telescopes document such brief visitors, their stories continue to contribute to the expansion of humankind’s cosmic horizon.