Comet C/2025 A6 (Lemmon), a celestial visitor that has brightened dramatically throughout October, is providing a spectacular alignment for stargazers. Tonight, October 26, 2025, the comet will pass through the neck and head of the constellation Serpens Caput, popularly known as the "cosmic serpent."
This close alignment in our line of sight offers a unique viewing opportunity as the hazy glow of the comet appears nestled among the stars that form the head of the great snake, which is held by the constellation Ophiuchus (the Serpent Bearer).
🧐 The Cosmic Serpent: Serpens Caput
The "cosmic serpent" is the constellation Serpens, the only one that is split into two non-contiguous parts: Serpens Caput (Serpent's Head) to the west and Serpens Cauda (Serpent's Tail) to the east, separated by Ophiuchus. As Comet Lemmon moves rapidly across the sky, it is cutting directly through the head section of the serpent.
Tonight's Passage: The comet will be visible near the stars that form the triangular head of Serpens Caput after sunset.
Tomorrow's View: By the following night, October 27, the comet will have moved further, appearing closer to the constellation Ophiuchus.
✨ Comet Lemmon's Visibility and Current Status
Comet Lemmon, which was discovered on January 3, 2025, by the Mount Lemmon Survey, has surprised astronomers by becoming significantly brighter than initially predicted, making it a spectacular sight for late 2025.
Current Brightness: The comet is currently estimated to have an apparent magnitude of around +4.3 to +4.9.
Naked-Eye Visibility: This brightness makes it potentially visible to the unaided eye from dark sky locations, away from city lights and light pollution. From less-dark areas, it appears as a fuzzy glow, but binoculars or a small telescope are highly recommended to get a clearer view of its bright coma and faint tail.
Location: Look low toward the western/southwestern horizon shortly after sunset and the end of civil twilight. In the Northern Hemisphere, it sets relatively early.
Closest Approach: Its closest approach to Earth (perigee) already occurred on October 21, 2025, at a distance of about 28.6 million miles (46 million kilometers). While it was expected to be brightest on that date, the comet remains bright for several days before and after its closest pass.
Perihelion: The comet is currently on its inbound journey toward the Sun, with its closest approach to the Sun (perihelion) scheduled for November 8, 2025.
🔭 Tips for Viewing Tonight
To maximize your chances of seeing Comet Lemmon as it passes the cosmic serpent:
Find a Dark Sky: Move to a location with minimal light pollution and a clear view of the western/southwestern horizon.
Timing: Start looking shortly after sunset, once the sky is fully dark, as the comet is low and will set within a few hours.
Equipment: Use a good pair of binoculars (e.g., 8x42 or 10x50) to spot the comet's characteristic hazy patch and its short tail.
Reference Point: The comet will be visible in the region near where the constellations Boötes (the Herdsman) and Serpens Caput meet, though its exact location changes rapidly night to night.
This is a rare opportunity to witness a comet on an orbit of approximately 1,150 to 1,350 years, meaning its next visit won't be until around the year 3175. Don't delay your viewing, as the comet will begin to fade and move to a less favorable position as it progresses on its orbital path.