In 1995 a spacecraft called the Solar and Helio-spheric Observatory (SOHO) was placed into a circular orbit

Question:

In 1995 a spacecraft called the Solar and Helio-spheric Observatory (SOHO) was placed into a circular orbit about the sun and inside that of the earth as shown. Determine the distance h so that the period of the spacecraft orbit will match that of the earth, with the result that the spacecraft will remain between the earth and the sun in a “halo” orbit.