3753 cruithne is about 5 kilometres (3.1 mi) in diameter. from 1994 through 2015, 3753 cruithne makes its annual closest approach to earth every november. although cruithne's orbit is not thought to be stable over the long term, calculations showed that it has probably been synchronized with earth's orbit for a long time. there is no danger of a collision with earth for millions of years, if ever. its orbital path and earth's do not cross.