How to See Comet Lemmon During Its Once-in-a-Lifetime Visit

Rare Comet Lemmon Makes Once-in-a-Lifetime Visit

Comet C/2025 A6 (Lemmon) is currently making a rare appearance in the skies near Earth, offering skywatchers a unique opportunity to witness this extraordinary celestial event that won’t happen again for over a thousand years. Discovered in January, the comet is now reaching its closest approach to Earth, becoming visible to the naked eye from dark-sky locations. This once-in-a-lifetime event is truly a spectacle to behold, with Lemmon’s orbit taking more than a millennium to complete, meaning it won’t grace our skies again until around the year 3175.

The bright green comet, known as C/2025 A6 Lemmon, will be dazzling spectators alongside a bright star called Cor Caroli on Thursday, October 16. It was first detected on January 3 through the Mount Lemmon Survey, a program that conducts sky scans using a 60-inch telescope atop Mount Lemmon in Arizona. With an orbital period of around 1,350 years, Lemmon’s encounter with the Sun in November will alter its path, shortening its orbit to 1,150 years. Since its discovery, the comet has brightened significantly, making it visible to the naked eye under ideal dark sky conditions despite potential interference from the glow of the waning gibbous moon.

As Comet Lemmon approaches the Sun, it is expected to brighten rapidly, revealing a soft green glow and a delicate, wispy tail as solar wind strips away its icy surface. This transformation will make it even more captivating for skywatchers eager to catch a glimpse of this rare celestial visitor. The comet is expected to remain visible from mid-October through early November, with the best viewing opportunities around October 21 when it reaches its closest point to Earth. Despite dimming as it approaches the Sun, Comet Lemmon will still be visible under clear, dark skies, particularly in late October as it glides through twilight.

For those in the northern hemisphere, October offers the best viewing window for Comet Lemmon. Observers should look towards the low western sky after sunset, just below the Big Dipper, for a chance to witness this celestial show. The comet will also pass near the bright star Cor Caroli midway through the month before continuing its journey towards the Sun. While skywatchers in the southern hemisphere will have a brief opportunity to see Comet Lemmon in November, visibility may be limited due to its position lower on the horizon.

To spot Comet Lemmon from Earth, experts suggest waiting until the sky darkens after sunset and looking towards the west-northeast with the Big Dipper as a reference point. While binoculars or a small telescope can enhance the viewing experience, the comet should appear as a faint, fuzzy greenish glow to the naked eye. Photographers aiming to capture this celestial phenomenon are advised to use long exposures to reveal the comet’s delicate tail, which has already started to interact with the solar wind. Although Lemmon’s current orbital period is approximately 1,350 years, its upcoming close encounter with the Sun will reduce this to 1,150 years, meaning that skywatchers won’t have another chance to witness its dazzling display until the distant year of 3175.

The rare visit of Comet Lemmon offers a captivating glimpse into the wonders of our universe, reminding us of the awe-inspiring beauty that exists beyond our own planet. Skywatchers and astronomy enthusiasts alike are sure to treasure this once-in-a-lifetime event, savouring the opportunity to witness a celestial spectacle that has captured imaginations for centuries. The ethereal green glow and delicate tail of Comet Lemmon serve as a poignant reminder of the vastness and mystery of the cosmos, inspiring wonder and curiosity in all who turn their gaze towards the heavens.