Researchers have identified two dozen planets outside our solar system that may have more suitable conditions to support life than earth.

In a study led by Washington State University scientist Dirk Schulze-Makuch, researchers have identified 24 ‘superhabitable’ planets where life can thrive better than on earth. The study has been published in the journal Astrobiology.

These exoplanets, which are all more than 100 light years away, are “older, a little larger, slightly warmer and possibly wetter than earth”.

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Criteria for habitability

Schulze-Makuch collaborated with astronomers René Heller of the Max Planck Institute for Solar System Research and Edward Guinan of Villanova University for the study. The researchers identified the criteria for superhabitability within the 4,500 known exoplanets beyond our solar system. Planets that are more habitable would be more conducive to life.

“The researchers selected planet-star systems with probable terrestrial planets orbiting within the host star’s liquid water habitable zone from the Kepler Object of Interest Exoplanet Archive of transiting exoplanets,” explained the release.

They also looked at exoplanets located in a system with G stars that are similar to our sun but are less warm. They also looked at planets orbiting K stars which have a much longer lifespan of 20 billion to 70 billion years.

Size and mass were also important factors. A planet whose size is 10 per cent more than our planet is likely to have more habitable land. Furthermore, planets that have nearly 1.5 times the mass of earth are also likely to retain its interior heating for a longer period of time through “radioactive decay”. The gravity on these planets is also expected to be stronger than on earth. Slightly warmer planets with additional moisture are also more conducive to life.

Among the 24 planets identified by the study, none met all the set criteria for superhabitable planets. However, one of the planets had four of the critical criteria to provide a more comfortable environment for life than our home planet.

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“It’s sometimes difficult to convey this principle of superhabitable planets because we think we have the best planet,” said Schulze-Makuch. “We have a great number of complex and diverse lifeforms, and many that can survive in extreme environments. It is good to have adaptable life, but that doesn’t mean that we have the best of everything.”

Further research

More information can be gathered using data from projects such as NASA’s James Web Space Telescope, the LUVIOR space observatory and the European Space Agency’s PLATO space telescope.

“With the next space telescopes coming up, we will get more information. So, it is important to select some targets,” said Schulze-Makuch. “We have to focus on certain planets that have the most promising conditions for complex life. However, we have to be careful to not get stuck looking for a second earth because there could be planets that might be more suitable for life than ours.”

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