A bright new solar system comet is set to dazzle stargazers in the October night sky as it approaches Earth. Comet C/2025 R2 (SWAN), discovered on September 10 by Ukrainian amateur astronomer Vladimir Bezugly, has shown a significant increase in brightness. This enhancement raises hopes that it could become a naked eye comet around its closest approach to our planet on October 21.
As Comet C/2025 R2 (SWAN) draws nearer to the sun, the intense heat causes the frozen materials in its nucleus to undergo a process called sublimation. This transformation leads to the solid materials turning into gas, forming a gaseous shell around the comet. The solar wind then sweeps this gas and dust away, producing a long, radiant tail that reflects sunlight. If conditions are favorable, this cosmic spectacle could be visible to the naked eye from Earth.
The comet reached its closest point to the sun, known as perihelion, on September 12, passing just under 47 million miles from our star—approximately half the average distance of Earth's orbit. Understanding brightness is essential when observing celestial bodies. The magnitude scale measures the apparent brightness of objects in the night sky; lower numbers indicate brighter objects. For reference, the brightest stars shine around magnitude +1, while the full moon is rated at -13 and the sun at -27.
Recent observations from the Comet Observation Database (COBS), managed by the Crni Vrh Observatory in Slovenia, have reported C/2025 R2 (SWAN) at a brightness of magnitude 5.6. This means that under ideal dark sky conditions, it could be visible as a very faint naked eye object. Notably, the human eye can detect night sky objects with a magnitude lower than +6. For those seeking a clearer view, binoculars or a telescope will significantly enhance visibility.
Stargazers can observe Comet C/2025 R2 (SWAN) in the evening sky throughout October, particularly in the hours following sunset before it sets low on the south-southwest horizon. On October 16, the comet will be located approximately 5 degrees to the upper left of the star Xi Serpentis, in the eastern part of the constellation Serpens. If you are unfamiliar with the night sky, using a stargazing app on your mobile device can assist in locating the comet.
In the following week, Comet C/2025 R2 (SWAN) will pass above the well-known teapot asterism in the constellation Sagittarius, making its way through the stars of the constellation Scutum. By the end of the month, this wandering solar system body will be visible above the southern horizon, situated between the bright stars Sadalmelik and Sadalsuud in the constellation Aquarius, with the half-lit moon shining below.
For those eager to catch a glimpse of C/2025 R2 (SWAN), we recommend checking out our roundups of the best binoculars and telescopes for viewing the night sky. Additionally, if you're interested in capturing images of this solar system comet with a DSLR camera, be sure to explore our guide on imaging solar system comets.
