A satellite GeoSAT is in a circular geostationary orbit of radius $R_G$, above a point P on the equator. Another satellite ComSAT is in a lower circular orbit of radius $0.81 R_G$. At 7 P.M on January 1, ComSAT is sighted directly above P. On which day among the following can ComSAT be sighted directly above P between 7 P.M. and 8P.M.?

• A

  January 3
• Correct answer
  B

  January 9
• C

  January 15
• D

  January 21

Hence, the correct answer is option: 'B'.