Comet Lemmon Approaches Earth, Potentially Visible to Naked Eye in October

Comet C/2025 A6 (Lemmon), discovered on January 3, 2025, by the Mount Lemmon Survey in Arizona, is rapidly brightening as it approaches Earth and the Sun. Currently visible through small telescopes and binoculars, it may become visible to the naked eye later this month.

The comet will reach its closest point to Earth on October 21, passing approximately 55.4 million miles (89.2 million kilometers) away. It will then reach perihelion, its closest approach to the Sun, on November 8, at a distance of about 49.25 million miles (79.25 million kilometers).

In early October, Comet Lemmon is located in the constellation Ursa Major, making it a morning object. Observers are advised to look approximately 90 minutes before sunrise. By mid-October, it will transition to the evening sky, becoming visible shortly after sunset. On October 16, the comet will be near the star Cor Caroli in the constellation Canes Venatici, aiding in its location.

Predictions about the comet's brightness vary. Some forecasts suggest it could reach a magnitude of +3, making it comparable in brightness to the star Megrez in the Big Dipper. However, comet brightness can be unpredictable, and actual visibility may differ.

For optimal viewing, observers should seek dark-sky locations away from urban light pollution. Under clear, dark skies, the comet may appear as a diffuse, glowing object with a faint tail. As it continues its journey through the inner solar system, Comet Lemmon offers a unique opportunity for skywatchers to observe a celestial visitor that last passed through the inner solar system over a millennium ago.