Australian researchers have suggested that finding rocky, Earth-like exoplanets that can sustain life will be crucial for us as a species.
An artist’s impression of the recently discovered Earth-like planet Gliese 581g (Lynette R. Cook)
In the new study, published in the Annual Reviews of Earth and Planetary Sciences, the researchers also claim that these exoplanets are more abundant than stars.
“Determining whether these planets are habitable has become the new holy grail of astronomy,” said Dr. Charley Lineweaver, a planetary scientist at the Australian National University and a lead author of the study.
“The new-found abundance of planets, combined with the much larger range of inhabited terrestrial environments suggests that habitable planets are common,” the scientist added. “This increases the probability of finding some kind of extraterrestrial life.”
Reviewing recent exoplanet discoveries, the researchers estimated that almost every star has at least one planet, and that the fraction with rocky planets, including habitable worlds, may be comparably large.
“Our best estimates of habitability come from the planet we know best: Earth,” explained Aditya Chopra, a fellow researcher and PhD student at the Australian National University and a co-author of the study.
“By comparing the inhabited and uninhabited regions of Earth, we can identify the most important factors that determine habitability. For terrestrial life, those factors are liquid water, a narrow range of temperature, and an energy source.”
“Habitability is not just a question of abiotic environmental conditions – the presence of life may be required to maintain the habitability of a planet over billions of years,” Dr. Lineweaver said. “The study of the habitability of other Earths is the major focus of astrobiology – and increasingly planetary science and astronomy.”
“Planetary habitability is a complex and confusing concept that we are only beginning to get our heads around, but as a species that wants to survive, it is in our interest to get our heads around it soon,” the researcher concluded.
