New Comet C/2025 R2 (SWAN) Poised for October Visibility

A newly discovered comet, designated as C/2025 R2 (SWAN), is expected to approach Earth in October, potentially becoming visible to the naked eye. The comet was identified by Vladimir Bezugly from Dnipro, Ukraine, on September 10 while examining images captured by the Solar Wind Anisotropies (SWAN) camera aboard the Solar and Heliospheric Observer (SOHO) spacecraft. The discovery occurred while Bezugly analyzed low-resolution images taken between September 5 and 9. He noted, “In my memory, this is one of the brightest comet discoveries ever made on SWAN imagery,” marking it as the 20th official SWAN comet.

Since its discovery, amateur astronomers, particularly in the Southern Hemisphere, have successfully spotted the comet. On September 15, it received formal designation from the International Astronomical Union. The comet passed the bright star Spica on the same day, as captured in photographs by Gerald Rheemann and Michael Jäger.

To assess the brightness of celestial bodies, astronomers utilize a scale known as magnitude. This scale measures the apparent brightness of objects, where lower numbers indicate brighter appearances. The brightest stars typically fall within the range of magnitude 0 to +1, while objects with a magnitude of +6.5 can just be seen with the naked eye under optimal conditions. Current observations place Comet SWAN at a magnitude of +7, slightly beyond naked-eye visibility but readily observable with good binoculars.

For those interested in viewing the comet, it is currently characterized by a small, condensed head or coma with a faint tail extending approximately two degrees. Binoculars such as the Nikon Prostaff P3 8×42 offer a user-friendly option for stargazers, featuring solid optics and a durable design.

An orbit of Comet SWAN has been calculated based on 60 observed positions from September 12 to 14. According to Syuichi Nakano of the Central Bureau for Astronomical Telegrams, the comet passed its closest point to the sun, or perihelion, on September 12, at a distance of about 46.74 million miles (75.20 million km). As it moves away from the sun, it is also approaching Earth. The closest encounter, or perigee, is expected to occur on October 21, when the comet will be approximately 25.10 million miles (40.38 million km) away.

Predictions regarding the comet’s brightness vary, with experts such as Seiichi Yoshida and Gideon Van Buitenen forecasting a peak magnitude between +6 and +7 during its closest passage to Earth in the third week of October. Daniel W.E. Green, also from the Central Bureau for Astronomical Telegrams, suggests that Comet SWAN may hover around magnitude +6 from October 2 to 20, potentially becoming faintly visible to the naked eye around October 12.

As the month progresses, Comet SWAN will gradually shift its visibility from the Southern Hemisphere to the Northern Hemisphere. By early October, it will ascend higher in the southwest sky, reaching about 12 degrees above the horizon by the end of evening twilight. By October 28, the comet is expected to climb to 30 degrees above the south-southwest horizon, making it more accessible for observers.

Throughout October, Comet SWAN will traverse several constellations, including Libra, Scorpius, Ophiuchus, Serpens, Scutum, Sagittarius, Aquila, and Aquarius. Observers should prepare for potential challenges, particularly in areas affected by light pollution, as the comet’s visibility may be hindered.

An additional point of interest has emerged regarding the possibility of a meteor shower associated with Comet SWAN between October 4 and 6. Some diagrams suggest that the comet’s orbit intersects with Earth’s orbit around October 5. Nonetheless, Joe Rao, an instructor at New York’s Hayden Planetarium, clarifies that the comet’s orbit lies significantly higher than Earth’s, meaning any potential meteoroids shed during its passage would miss our planet by approximately 4.4 million miles (7 million km).

While the concept of a meteor shower is intriguing, Rao emphasizes that the likelihood of such an event occurring is minimal, given the gaseous composition of Comet SWAN and its trajectory. As observers await the comet’s arrival, excitement builds over what may soon be visible in the night sky.