In 2017, astronomers at the Pan-STARRS1 observatory spotted an object as it hurtled past our Sun at 38.3 kilometers per second (23.8 miles per second) Scientists were able to determine its size and shape, finding it is around 400 meters (1,300 feet) long, and likely shaped like a pancake. Advertisement Advertisement The object is likely an interstellar planetesimal, which lost hydrogen in its encounter with our Sun, altering its velocity.