In this booklet, we have studied the extrasolar planets (exoplanets) employing the spin-orbiting coupling existing in the gravitating system. We tested the consistency of the primary observed data of these exoplanets. The primary parameters pertaining to the exoplanet-star system are found to be connected by a formula that we call it the Fourth Kepler's Law. This law is also used to address fundamental issues related to existence of life in these extrasolar systems.