Assuming that the radius of the great circle is 2, the diameter of the small circle is 2, the radius of the small circle is 1, and the formula for calculating the circumference of the great circle is 2πR=4π, and the circumference of the small circle is 2πR=2π, then the small circle rolls one circumference of the great circle when it returns to its original position, so it is 4π, which is two weeks relative to the small circle.