Two comets — C/2025 A4 (Lemmon) and C/2025 R2 (SWAN) — are nearing their closest approach to Earth, and sky watchers can witness this rare cosmic event live online.
Astronomer Gianluca Masi and the Virtual Telescope Project will host a special livestream on Oct. 20 at 1:30 p.m. EDT (1730 GMT), allowing viewers worldwide to observe both comets as they pass close to Earth and reach optimal visibility.
“So far, from the Northern Hemisphere, I’ve been able to observe C/2025 A6 Lemmon,” Masi told Space.com via email. “But now C/2025 R2 SWAN is joining the show, and we’re ready to amaze astronomy enthusiasts with our live broadcast!”
A Rare Double-Comet Encounter
It’s uncommon for two bright comets to grace Earth’s skies simultaneously. During this celestial event, Comet Lemmon (C/2025 A6) will come within 56 million miles (90 million km) of Earth, while Comet SWAN (C/2025 R2) will pass even closer — about 24 million miles (39 million km) away. Both comets are expected to reach peak brightness between October 20 and 21.
Comet Lemmon was first discovered in January 2025 and has been steadily brightening as it journeys through the inner solar system. It can currently be seen in the western evening sky after sunset using binoculars or a small telescope, appearing higher each night as it moves northward.
Comet SWAN, discovered in September 2025 by the SWAN instrument aboard the Solar and Heliospheric Observatory (SOHO), is best observed in the predawn eastern sky as it continues moving away from the Sun.
