Its speed, hyperbolic trajectory, and approach path from the direction of the constellation Sagittarius offered definitive proof that it formed around another star before being ejected into deep interstellar space.
By December 19, 2025, it will pass within 170 million miles of Earth— roughly twice the distance between Earth and the Sun — and well above any threat threshold.
The comet also made a close pass of the Sun on October 30, coming within 130 million miles, just inside the orbit of Mars.
See first images from Vera C. Rubin Observatory
How Big Is the Interstellar Comet?
Although its exact size remains uncertain, the European Space Agency estimates the object could span hundreds of feet to several miles across.
According to Hubble Space Telescope observations, the comet’s icy nucleus may be anywhere from 1,400 feet to 3.5 miles wide — still small compared to typical solar system comets but enormous as a wandering interstellar object.
How to See 3I/ATLAS in December
NASA confirms that 3I/ATLAS is visible in the pre-dawn sky, but only through telescopes or high-end binocular systems.
