Rare three green comets 'visit' Earth

Three blue comets, Lemmon, Swan and 3I/ATLAS, simultaneously approached Earth in October, creating a magical light show in the Milky Way.

Comet Lemmon (C/2025 A6) - Photo: X

The appearance of three green comets at the same time is considered one of the most interesting and rare astronomical phenomena in 2025, according to Argentine newspaper El Diario 24.

Comet Lemmon

Comet Lemmon was discovered by astronomers on January 3, 2025 at Mount Lemmon Observatory (Arizona, USA).

After months of monitoring, they said Lemmon had become brighter and could be seen with binoculars or even with the naked eye in dark conditions.

Under the lens of astronomers, this comet appeared with a blue tail extending more than 12 degrees, or 25 times larger than the apparent size of the Moon.

According to El Diario 24 , Lemmon reached its peak brightness on October 9, creating a spectacular scene that stretched across the Milky Way. On October 21, it approached Earth at its closest, which was also the ideal time for observation, according to British science site IFLScience Limited.

Swan's Comet

Comet Swan (C/2025 R2) - Photo: Bluesky

Comet Swan was discovered in September by Ukrainian astronomer Vladimir Bezugly using images from NASA's SOHO spacecraft. Traveling at a distance of 24 million miles (nearly 39 million km), Swan became brighter as it approached Earth.

On October 20 and 21, Swan will be closest to us: it will appear in the southwest, in the constellation Aquila. In areas with little light pollution and no moon, Swan will be visible to the naked eye.

According to Professor Emmanuel Jehin, an astrophysicist at the University of Liège (Belgium), it is very rare for two comets to be visible to the naked eye in the same season, usually only happening once every 10 years.

Both Lemmon and Swan fly quite close to the Sun, about half the distance from Earth to the Sun, causing their activity to increase and become brighter when reflecting light, he said.

Comet 3I/ATLAS 10 billion years old

Comet 3I/ATLAS - Photo: Bluesky

3I/ATLAS is a visitor from outside the Solar System, considered by scientists to be a valuable message from deep space. 3I/ATLAS was discovered in May 2025 within the framework of the ATLAS Astronomical Survey Program (Hawaii).

The comet is so dim and unstable that scientists predict it could break apart as it approaches the Sun. Initial analysis suggests it may have formed more than 10 billion years ago in an ancient region of the Milky Way.

Researcher Nicolas Biver, from the Institute of Astrophysics of the Paris Observatory (France), said 3I/ATLAS is like a "time capsule" containing chemical traces of the first star systems.

Comparing its composition with comets in the Solar System helps scientists better understand whether the material that forms planets has properties common across the galaxy, or differs according to each stage of evolution.

Scientists say 3I/ATLAS is moving at about 210,000km/h and will only be visible through telescopes.

According to the US National Aeronautics and Space Administration (NASA), the fact that three comets shine together in one month is a rare coincidence, proving the vitality of space near Earth, while astronomers describe this as a magical "cosmic parade".

The event also reminds people of their smallness in the vastness of space, where every streak of light in the sky carries billions of years old stories of the Milky Way.

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Source: https://tuoitre.vn/hy-huu-ba-sao-choi-xanh-cung-ghe-tham-trai-dat-20251022150641065.htm