While it's theoretically possible for a comet to collide with the Earth, such events are extremely rare. Studies estimate that comets measuring 0.3 kilometers in diameter strike Earth approximately once every 500 years, whereas those with a diameter of 1.6 kilometers impact our planet about once every 6,000 years. The likelihood of a comet the size of Shoemaker-Levy 9 (1.5-2 kilometers) colliding with the Earth is estimated to occur once every 10 million years. If this comet had impacted Earth instead of Jupiter, it could have potentially eradicated life as we know it. Scientists actively monitor near-Earth objects to assess any potential threats.