[4] Cruithne was discovered on 10 October 1986 by Duncan Waldron on a photographic plate taken with the UK Schmidt Telescope at Siding Spring Observatory, Coonabarabran, Australia.

A 1983 precovery (1983 UH) is credited to Giovanni de Sanctis and Richard M. West of the European Southern Observatory in Chile.

Its period of revolution around the Sun, approximately 364 days in the early 21st century, is almost equal to that of Earth.

[citation needed] After 380 to 390 years or so, the kidney-bean-shaped orbit approaches Earth again from the other side, and Earth, once more, alters the orbit of Cruithne so that its period of revolution around the Sun is again slightly less than a year (this last happened with a series of close approaches centred on 1902, and will next happen with a series centered on 2676).

Mars has four known co-orbital asteroids (5261 Eureka, 1999 UJ7, 1998 VF31, and 2007 NS2, all at the Lagrangian points), and Jupiter has many (an estimated one million greater than 1 km in diameter, the Jovian trojans); there are also other small co-orbital moons in the Saturnian system: Telesto and Calypso with Tethys, and Helene and Polydeuces with Dione.

Cruithne plays a major role in Stephen Baxter's novel Manifold: Time, which was nominated for the Arthur C. Clarke Award for best science fiction in 2000.

Cruithne is mentioned on the QI season 1 episode "Astronomy", in which it is described as a second moon of Earth.

[14] In the Insignia trilogy, 3753 Cruithne has been moved into an orbit around Earth to serve as a training ground for the Intrasolar Forces.

While it is destroyed before impact, its fragments rain down on Earth's surface, killing nearly 800 million people across the world.