Comets SWAN and Lemmon to Make Closest Approaches to Earth in October
Comets C/2025 R2 (SWAN) and C/2025 A6 (Lemmon) will pass near Earth in October, offering skywatchers a rare opportunity to observe both comets in the night sky.
Two newly discovered comets, C/2025 R2 (SWAN) and C/2025 A6 (Lemmon), are set to make their closest approaches to Earth this month, providing a unique viewing opportunity for astronomers and enthusiasts alike.
Comet SWAN, identified on September 12, 2025, by NASA's Solar Dynamics Observatory, will come within approximately 24 million miles (38.6 million kilometers) of Earth on October 20. Comet Lemmon, discovered on January 3, 2025, by the Mount Lemmon Observatory in Arizona, will pass at a distance of about 55 million miles (88.5 million kilometers) on October 21.
Both comets are expected to be visible with binoculars or small telescopes. Comet Lemmon may even become faintly visible to the naked eye under dark skies, potentially reaching a magnitude of around 4.
Observing conditions are favorable, as the new moon on October 21 will result in darker skies. For optimal viewing, observers should find a location away from light pollution and use binoculars or telescopes.
These comets originate from the Oort Cloud, a distant region of icy bodies at the edge of the solar system. Their appearances offer scientists a chance to study materials that have remained largely unchanged since the solar system's formation.
Skywatchers are encouraged to seize this rare opportunity, as Comet SWAN will not return for another 650 to 700 years, and Comet Lemmon will remain out of sight for approximately 1,300 years.