Comets Lemmon and SWAN to Approach Earth on October 20
Two comets, C/2025 A4 (Lemmon) and C/2025 R2 (SWAN), are set to make their closest approach to Earth on October 20, 2025, providing a rare opportunity for skywatchers to observe these celestial bodies live online. The event will be hosted by astronomer Gianluca Masi and his Virtual Telescope Project, with a special livestream beginning at 1:30 p.m. EDT (1730 GMT).
Astronomer Masi expressed excitement about the upcoming event, stating, “So far, living in the Northern Hemisphere, I could admire C/2025 A6 Lemmon only, but C/2025 R2 SWAN is quickly joining the show, and we are ready to amaze every astronomy lover with our live feed!” The livestream can be accessed on Space.com, as well as the Virtual Telescope Project’s website and YouTube channel, weather permitting.
Rare Double-Comet Encounter
The simultaneous visibility of two comets is a unique astronomical occurrence. During their close pass, Comet Lemmon will come approximately 56 million miles (90 million kilometers) from Earth, while Comet SWAN will pass even closer at about 24 million miles (39 million km). Both comets are anticipated to reach peak brightness between October 20 and October 21.
Discovered in January 2025, Comet C/2025 A4 (Lemmon) has been steadily brightening as it travels through the inner solar system. It can be seen with binoculars or small telescopes in the western evening sky after sunset, gradually climbing higher each night as it moves northward. In contrast, Comet C/2025 R2 (SWAN) was discovered in September 2025 by the Solar and Heliospheric Observatory’s SWAN instrument. It is best viewed in the predawn sky, appearing low on the eastern horizon as it continues its journey away from the sun.
For those hoping to catch a glimpse of these comets firsthand, guides to the best binoculars and telescopes for beginners are available, along with tips on how to photograph comets. Skywatchers are encouraged to explore additional celestial highlights in the night sky this month.
For anyone who captures a photo of Comet Lemmon or Comet SWAN, Space.com invites submissions at [email protected]. This event promises to be an exciting opportunity for astronomy enthusiasts and casual observers alike.
