Rare Green Comet lemmon to Grace October Skies after Millennia-Long Journey
JAKARTA, Indonesia – Skywatchers are preparing for a celestial spectacle as Comet Lemmon, a visitor from the outer solar system, is predicted to be visible in the Indonesian night sky starting in early October 2025. The comet, returning after an estimated thousands of years, has captivated the astronomical community due to its speed and distinctive green glow.
First detected traveling towards the inner solar system at speeds reaching 130,000 mph (209,000 km/h), Comet Lemmon is currently exhibiting characteristics that make it particularly noteworthy. As it approaches the sun, its icy surface is vaporizing, forming a coma – a thin atmosphere surrounding the comet’s nucleus – and a possibly vast tail.
The comet’s striking green hue is attributed to the presence of diatomic carbon (C2) in its coma, which emits green light when exposed to solar radiation. This phenomenon is similar to that observed in other recent comets, including C/2022 E3 (Green Comet) in 2023 and 12P/Pons-Brooks (Devil’s Comet) in 2024. Intense solar winds in late September caused the comet’s tail to appear wavy.
According to astronomer Thomas Djamaluddin from the National Research and Innovation Agency (BRIN), the best viewing time for observers in the northern hemisphere, including Indonesia, will be in early October 2025, before sunrise.The comet will reach its closest position on Saturday, October 20, 2025, with optimal viewing between 04:00 WIB and sunrise.
After October 12, 2025, the comet can be observed after Maghrib (sunset) in the western sky. It will become easier to see and brighter after October 15, potentially reaching a magnitude of 2.5 by the end of October – bright enough to be visible without a telescope under favorable conditions with minimal light pollution.
