The interstellar object known as 31/ATLAS, more formally designated 3I/ATLAS, will make its closest-ever approach to Earth on Friday, Dec. 19, giving astronomers and the public a once-in-a-universe opportunity to observe a visitor from another star system. The Virtual Telescope Project is planning a live global broadcast of the event.
Scientists say this fleeting encounter offers an unprecedented chance to study how planetary systems beyond our own may form and evolve.
Discovered on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile, 3I/ATLAS is only the third confirmed interstellar object ever detected passing through our solar system. It follows 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019.
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A Once-in-a-Cosmic-Lifetime Encounter
According to Space.com, Dec. 19 marks the moment when “this erratic wanderer will be the closest to Earth that it will ever be over the lifetime of the entire universe.” At that point, 3I/ATLAS will be about 168 million miles (270 million kilometers) from Earth.
