Skywatchers have a rare chance this month to witness two bright comets — C/2025 A6 Lemmon and C/2025 R2 SWAN — streak across the heavens as they make their closest approach to Earth.
As CNN reports, both icy bodies were discovered only months apart, with Lemmon spotted by the Mount Lemmon Observatory in Arizona on January 3, and SWAN identified by Ukrainian astronomer Vladimir Bezugly on September 10 using NASA–European Space Agency data from the Solar and Heliospheric Observatory.
According to astronomer Quanzhi Ye of the University of Maryland, SWAN will pass within 38.6 million kilometres of Earth on October 20, followed by Lemmon at 88.5 million kilometres a day later. The two appear near the Sun, making them visible only briefly — SWAN after dusk and Lemmon before dawn.
Experts told CNN that both comets are long-period travellers from the Oort Cloud, a distant region of icy debris. Dr Carrie Holt from Las Cumbres Observatory explained that such comets preserve “materials that have barely changed since the solar system’s beginning,” offering insights into its early formation.
Comet Lemmon, currently brightening, could soon be visible to the naked eye from the Northern Hemisphere, while SWAN favours observers in the south. Astronomers recommend viewing from dark skies with binoculars or telescopes — or tuning into the Virtual Telescope Project’s livestream from Italy if clouds spoil the view.