Icarus makes a close approach to Earth at gaps of 9, 19, or 38 years. Sometimes, it comes as close as 6.4 Gm (16 lunar distances and 4 million miles), as it did on June 14, 1968. The last close approach was in 1996, at 15.1 Gm, about 40 times as far as the Moon.[2] The most recent close approach was on June 16, 2015, 8.1 Gm (5 million miles).
↑Project Icarus, MIT Report No. 13, MIT Press 1968, edited by Louis A. Kleiman. "Interdepartmental Student Project in Systems Engineering at the Massachusetts Institute of Technology, Spring Term, 1967".