More than 200 giant extrasolar planets have been found over the past 15 years. Now, the focus of extrasolar planet searches is shifting towards the detection of habitable planets. If the goal is to find planets that could harbour life, these detected exoplanets are not good candidates. Most are gas giants with no solid surfaces and no liquid water. Finding terrestrial planets (not just planets) is the next big initiative in astronomy and the next big step towards understanding the Earth.
"Planetary mass, orbit and chemical compositions play an important role in habitability", says José Robles, a PhD candidate at the Australian National University’s Mount Stromlo Observatory in Canberra. "Unlike planetary mass and orbit, the planet's chemical compositions can be estimated based on the chemical compositions of stars. Although earth-like planets are currently beyond our detection limits, we can already begin to classify extrasolar terrestrial planets according to the observed chemical abundances of stars."
Robles has a physics degree with honours in Astronomy from the Universidad de las Américas, in Puebla, México. "My advisor got me interested in the ANU - RSAA is an internationally renowned Astrophysics school - and I arrived here in 2004. After working for a year in dwarf galaxy research, I was captured by the extraterrestrial habitability topic: 'what chemical elements are more relevant for life and how abundant are they?'. Whether extrasolar habitable planets are rare gems or common rocks of our Universe is something worth finding out."