It turns out interstellar comet 3I/ATLAS was almost called 3I/Rubin, after researchers found that the giant survey telescope coincidentally spotted this visitor from the stars over a week before it was officially discovered.
3I/ATLAS was officially identified on July 1, 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), which is a network of robotic telescopes in Hawaii, Chile and South Africa. But ten days before, the Vera C. Rubin Observatory, which is also in Chile, began its science validation phase ahead of entering full operation later that year. The science validation phase was designed to calibrate the 27.6-foot (8.4-meter) telescope and its instruments, to ensure that they were working correctly.
