20 years after the discovery of the first exoplanet, scientists on the Earth are at the gate of a new era -- observing planets similar to their own planet in the solar system around other stars, low mass stars in particular. This effort could potentially answer the long standing and arguably the most important scientific and philosophical question to human beings: are they alone in the Universe?　　 

　  However, such a promising and exciting scientific endeavor is not without hurdles. Currently there is a debate on what types of planets around what types of stars should be considered habitable within the scientific community on the Earth, based on the narrow perspective of life on the Earth. This debate is important because given the limited amount of funding and time available to this intelligent species, only the most promising planets will be selected as the targets for future telescope observations. 　　 

　 In this talk the most recent developments on planetary habitability and exoplanet missions selected by international space agencies on the Earth will be reviewed. It is concluded that despite the uncertainties regarding planetary habitability, a Golden Decades of exoplanet observations will arrive after 2020, which will settle most current debates on planetary habitability and help to better understand some imminent problems faced by the human being society.