The long-serving space telescope saw the third interloper to enter the solar system from beyond its limits late on Monday morning (July 21).

Scientists are racing to learn as much as possible about the interstellar comet 3I/ATLAS before it fades from view forever

The comet was discovered on July 1 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey telescope. Knowing where to look, Rubin’s team found observations of the comet from June 21. For this analysis, which awaits peer review, the astronomers have combined them with observations all the way to July 7.