In nine years, a big asteroid will come close enough to Earth that it will be visible with the naked eye. In 2036, Apophis will make a return trip, and Earthlings will again be safe. The year 2068, however, might be a different story. Scientists just made some new calculations and concluded that they can't rule out a collision with Earth, reports LiveScience. An impact remains unlikely, but that year is no longer in the definitely safe category. A post at Phys.org explains that astronomers factored in something called the Yarkovsky effect, which happens when the sun hits one side of an asteroid. "As the heat radiates away from the asteroid, a small amount of energy pushes back against the asteroid, forcing it to turn slightly," reads the post.
And this tiny adjustment—a difference of about 560 feet a year off the original orbit—means Apophis now has a shot at hitting Earth. "Basically, the heat that an asteroid radiates gives it a very tiny push," says University of Hawaii at Manoa astronomer David Tholen. Before this recalculation, astronomers thought Apophis had zero chance of hitting Earth in 2068, per Weather.com. The asteroid is 1,120 feet wide and thus capable of doing some real damage. The good news is that astronomers will have a much better sense of things after the 2029 flyby. For now, though, "the 2068 impact scenario is still in play," says Tholen. (More about the asteroid here.)