3753 Cruithne It was not until 1997 that its unusual orbit was determined by Paul Wiegert and Kimmo Innanen, working at York University in Toronto, and Seppo Mikkola, working at the University of Turku in Finland. Cruithne is approximately in diameter, and its closest approach to Earth is , approximately thirty times the separation between Earth and the Moon. From 1994 through 2015, Cruithne made its annual closest approach to Earth every November. Although Cruithne's orbit is not thought to be stable over the long term, calculations by Wiegert and Innanen showed that it has probably been synchronized with Earth's orbit for
Near-Earth Asteroid Scout mission researchers argue that "characterization of NEAs that are larger than 20 m in diameter is also of great relevance to inform mitigation strategies for planetary defense." The planned target, subject to change, is near-Earth object 1991 VG. 1991 VG was discovered shortly before passing just 0.003 AU from earth on 6 November 1991, and returned within 0.06 AU of Earth in August 2017. It raised interest due to the close approach, and the expectation that such an Earth-similar orbit would not have long term orbital stability. Once the flyby is complete, and if the system is still fully functioning,