New comet C/2025 R2 (SWAN): where and when to observe it in October 2025?

The comet C/2025 R2 (SWAN) was discovered on September 12, 2025 thanks to the SWAN camera (Solar Wind Anisotropies) aboard the SOHO spacecraft. This long-period comet, with an estimated orbit of about 22 554 years, offers amateur astronomers a rare observing opportunity.

Currently, the comet has an apparent magnitude of around 7, making it visible with binoculars under a dark sky. It travels across the constellations of the night sky, offering several observing opportunities. On October 2, it will pass near the star Zubenelgenubi (Alpha Librae), a useful reference point for observers. Its closest approach to Earth is expected on October 21, at a distance of 0.27 AU (about 40 million kilometers). At that time, the comet could reach a magnitude of 4, potentially visible to the naked eye under a clear sky.

To maximize your chances of observing the comet:

• Use binoculars : A standard pair of binoculars should be enough to spot the comet, especially if it reaches the expected magnitude.

• Choose a dark-sky observing site : Move away from urban lights to reduce light pollution and improve visibility.

• Consult sky maps : Apps or astronomical charts can help you locate the comet precisely based on your location and the date.

In October 2025, observing conditions will be particularly favorable, with a new moon on October 21, ensuring a dark sky. Additionally, the peak of the Orionids meteor shower will coincide with this period, offering an enriched celestial display.

Comets are unpredictable celestial objects, and their brightness can vary. It is therefore recommended to follow updates from astronomical observatories and amateur astronomer communities to obtain the most recent information on the visibility of C/2025 R2 (SWAN).