Cruithne, Earth’s “second moon"

753 Cruithne is an asteroid in orbit around the Sun in 1:1 orbital resonance with the Earth. It is a minor planet in solar orbit that, relative to Earth, orbits in a bean-shaped orbit that ultimately effectively describes a horseshoe, and which can transition into a quasi-satellite orbit. It has been incorrectly called "Earth’s second moon”. Cruithne does not orbit Earth and at times it is on the other side of the Sun. Its orbit takes it inside the orbit of Mercury and outside the orbit of Mars. Cruithne orbits the Sun in about 1 year but it takes 770 years for the series to complete a horseshoe-shaped movement around the Earth.