Double Green Comets Now Visible in Northern Hemisphere Skies: When and How to View This Rare Astronomical Event

Comets are ancient frozen remnants dating back billions of years to our solar system's formation period.

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Currently, two vibrant green comets are traversing the skies, visible to observers in the Northern Hemisphere.

These celestial visitors originate from the distant boundaries of our solar system, potentially from the theoretical Oort Cloud region beyond Pluto. Comet Lemmon is expected to make its closest approach to Earth on or around Tuesday. Meanwhile, Comet SWAN should pass by Earth on Monday, though it's moving away from the sun and will likely become less visible as time progresses.

According to Carson Fuls, director of the University of Arizona-based sky survey that discovered Comet Lemmon, seeing two comets simultaneously without specialized equipment is "rare, but not unprecedented."

To observe this celestial duo, head outdoors just after sunset and direct your gaze northward to find Comet Lemmon near the horizon. Comet SWAN will also be visible near the horizon, but in the southwestern direction.

Astronomer Valerie Rapson from the State University of New York at Oneonta notes that both comets should remain visible through binoculars until the end of the month, though experts aren't certain how bright they'll continue to be.

Comets represent frozen remnants from our solar system's creation billions of years ago. As they approach the sun, they heat up and release their distinctive streaming tails.

Comet Lemmon, also designated C/2025 A6, was first identified in January by a telescope searching for near-Earth asteroids. Comet SWAN, also known as C/2025 R2, was detected in September by an amateur astronomer using images from a spacecraft jointly operated by NASA and the European Space Agency.

The comets' green appearance results from gases emanating from their surfaces. From Earth's perspective, they will appear as grayish, fuzzy patches in the sky.

Earlier this year, another green comet disintegrated during its solar approach, disappointing hopes for a naked-eye spectacle. In recent years, other notable comets have included the bright Tsuchinshan-Atlas which passed Earth in 2024, as well as Neowise in 2020 and the memorable Hale-Bopp and Hyakutake comets in the 1990s.