Complex sentence: Some scientists speculate that this near-Earth asteroid could return because of the Earth's gravitational pull; some predict the next close encounter of 2009 DD45 with Earth's orbit will be in 2067.
Split into simpler sentences: Some scientists speculate that this near-Earth asteroid could return because of the Earth's gravitational pull. Scientists predict the next close encounter of 2009 DD45 with Earth's orbit will be in 2067.