Comet Lemmon Dazzles with Lime-Green Glow, Nears Earth Flyby

On October 2, 2025, astronomers are closely monitoring the movements of a newly discovered comet, dubbed "Lemmon," as it prepares for a close flyby of Earth later this month. Lemmon, a non-periodic comet with an orbital period of over 1,350 years, was first spotted on January 3 by researchers at the Mt. Lemmon SkyCenter observatory in Arizona.

The comet is currently speeding towards the inner solar system at up to 130,000 mph and is expected to reach its closest point to Earth on October 21, coming within 56 million miles of our planet. As Lemmon approaches the sun, its coma, or the cloud of gas and dust surrounding it, will expand, allowing it to reflect more sunlight and potentially become visible to the naked eye.

What makes Lemmon particularly intriguing is its striking lime-green glow, likely caused by the presence of diatomic carbon within its coma. This rare, gaseous form of carbon has been observed in several other green comets in recent years, including the "green comet" C/2022 E3 and the "devil comet" 12P/Pons-Brooks.

Experts believe Lemmon's upcoming solar flyby could significantly alter its future trajectory around the sun, potentially shortening its orbital period by up to 200 years. This is likely due to a recent close encounter with Jupiter, which has gravitationally tugged the comet off its original path.

As Comet Lemmon continues to brighten over the coming weeks, it will become an increasingly impressive sight in the morning sky, particularly for stargazers in the Northern Hemisphere. While it may not quite reach naked-eye visibility, the comet will be easily observable with a decent backyard telescope or a pair of binoculars.