New Way of Discovering Earth-like Exoplanets

Astronomers believe that they may have discovered a new way of determining where Earth-like exoplanets lie. They say that their location can be resolved by calculating the most likely places in the galaxy for photosynthesis to appear and develop. This is a basic process on Earth, as it allows all oxygen-breathing creatures to exist. Without it, plants would not release oxygen, and our existence would become unconceivable. This process could exist on other planets as well, and researchers believe they know how to look for it, Space reports.

The main paradigm in exoplanetary hunt today is the “habitable zone” focus. Experts are concentrating all of their resources towards discovering planets approximately the size of Earth, spinning at a particular distance around their stars. Each celestial fireball has such a zone, where temperatures are just right to support the existence of liquid water. Earth is located square in the middle of the Sun's habitable zone, and this is why the planet is covered in an ocean of liquid water. But the new strategy is not focused on detecting such zones, say experts from the Potsdam Institute for Climate Impact Research, in Germany.

Researchers here, led by physicist Werner von Bloh, argue that the most important condition for exoplanetary research should be the possibility of photosynthesis. They believe that astronomers should focus their attention on discovering the areas of a star system where the process may be possible. Photosynthesis is absolutely essential for supporting the emergence of complex life and aerobic (oxygen-breathing) organisms. A condition that comes attached with this approach is that the target exoplanet must have high carbon dioxide concentrations in its atmosphere. This would constitute the source of “food” for the prospective plants carrying out photosynthesis.

“Doing the simulations with planetary masses ranging from 0.1 with 10 Earth masses might be interesting. [In addition,] defining habitability based on carbon-based photosynthesis-performing life forms might be too Earth-centric. There might exist other life forms different from Earth life. Finding signs of life on other planets might be the most challenging goal in astrobiology,” von Bloh says. He added that future searches should focus on stars lighter than 2.2 solar masses. Heavier stars would deplete their hydrogen supplies in less than 800 million years, which is very little time for life to evolve.