Comets Lemmon, SWAN pass by Earth today: How to watch
What's the story
Two comets, C/2025 A6 (Lemmon) and C/2025 R2 (SWAN), are set to make their closest approach to Earth tonight. You can catch the action live online, thanks to astronomer Gianluca Masi and his Virtual Telescope Project. The livestream will begin at 1:30pm EDT (11:00pm IST). This is a rare opportunity as both comets will be visible in the sky at the same time.
Celestial event
Lemmon and SWAN's closest approach to Earth
Lemmon will pass within 89.9 million kilometers of Earth, while the SWAN will come even closer at some 39 million kilometers. Both are expected to peak in brightness between October 20 and October 21. Lemmon has been steadily brightening since its discovery in January 2025 and is now visible through binoculars or small telescopes in the western evening sky after sunset. SWAN, discovered in September by the Solar and Heliospheric Observatory's SWAN instrument, is best viewed in the pre-dawn sky.
Steps
When and where to see Lemmon
Lemmon will be visible in the northwest after sunset, rising higher as the night progresses. It will be at its brightest on October 21 when it passes within 89.2 million kilometers of Earth, before swinging around the Sun two weeks later at a distance of 79.25 million kilometers. The comet is currently shining at magnitude +4.9, that is bright enough to be seen through binoculars or small telescopes under dark skies.
Process
When and where to see SWAN
The comet SWAN, slightly dimmer at magnitude +5.9, will be visible in the southwestern sky. To find Lemmon in the sky, just look for the Big Dipper in the northwestern sky before dawn or shortly after sunset, and trace a banana-shaped curve along its handle to locate the Cor Caroli binary star system.