ABSTRACT
The twenty-first century has become a golden era for planetary systems. In addition, new planetary systems are being seen by those involved in this research, such as Gulkis [1], de Pater [2], Geoffrey Marcy [3], as well as other research institutions. A report supports that a total of 1800 such planets have been identified as of June 29, 2014 [4]. Besides, hundreds more systems are unconfirmed. In terms of total confirmed planets, the solar system with eight planets remains the largest known planetary system. However, HD 10180 has nine planets, of which two are yet unconfirmed [5], and is the largest known exoplanetary system including Kepler-90, which also has seven confirmed planets [6]. In fact, today, a wide range of planetary systems have been discovered, with different orbital arrangements around stars with their variety in types. Of all, the closest confirmed system is Gliese 832c [7] at 14.8 light years (ly) with one confirmed planet, whereas the closest unconfirmed system is Alpha Centauri [8] at 4.37 ly with a planet of Earth mass. On the other hand, the closest multiplanet system is Gliese 876 [9] at 15.3 ly with four confirmed planets. The present-day knowledge of planetary systems including that of the solar system has significantly increased beyond doubt, but much is still unknown about their origin and evolution. Scientists believe that the current theories of their formation and evolution are relatively new to the field of planetary science. A subject of particular interest is the field of astrobiology that is largely concerned with the habitable zone of planetary systems. This zone is believed to have the most potential to develop and sustain extraterrestrial life.
