Before YR4, there was Apophis. Discovered in 2004, the much larger asteroid briefly carried a significant future impact probability based on the early data. Years of optical and radar observations refined its route and set the stage for an astonishing 2029 encounter.
Apophis will pass only about 20,000 miles (32,000 kilometers) above Earth’s surface—closer than many communications satellites. Scientists expect to watch Earth’s gravity tug, stretch, and possibly alter the asteroid’s spin.
YR4 is smaller and its 2032 geometry is different, so this is not an apples-to-apples matchup. Together, though, they give this generation two spectacular observing campaigns only three years apart: one close to Earth, the other threading past Earth and within 13,200 miles of the Moon.