cruithne is in a normal elliptic orbit around the sun. its period of revolution around the sun, about 364 days at present, is almost equal to that of the earth. because of this, cruithne and earth appear to follow each other in their paths around the sun. this is why cruithne is sometimes called "earth's second moon". however, it does not orbit the earth and is not a moon. in 2058, cruithne will come within 13.6 million kilometres of mars. cruithne's distance from the sun and orbital speed vary a lot more than the earth's, so from the earth's point of view cruithne actually follows a kidney bean-shaped horseshoe orbit ahead of the earth, taking slightly less than one year to complete a circuit of the "bean". because it takes slightly less than a year, the earth "falls behind" the bean a little more each year, and so from our point of view, the circuit is not quite closed, but rather like a spiral loop that moves slowly away from the earth.