Not Earth: 24 Other Planets More Suitable For Life To Thrive, Say Scientists

Since we have not found signs of life outside of Earth yet, some might argue that Earth is the most habitable planet in the observable universe. A recent study by scientists, however, would prove it otherwise.

Artist¡¯s depiction of the first validated Earth-size planet to orbit a distant star in the habitable zone. (Image: NASA Ames/JPL-Caltech)

In a study, researchers from Washington State University have identified two dozen planets outside our solar system that display conditions more suitable for life than our own Earth. In fact, the study points out that some of these planets might be orbiting stars better than our Sun.

Recently published in the journal Astrobiology, the study describes ¡°superhabitable¡± planets as ones that are older as well as a little larger than Earth. It even indicates that the planet should be slightly warmer and wetter than Earth.

In the study, scientists have identified 24 top contenders for such superhabitable planets. All of these, however, are more than 100 light years away. While we may not be able to access them anytime in the near future, the study does help focus the search on signs of life in the universe.

¡°With the next space telescopes coming up, we will get more information, so it is important to select some targets,¡± said Schulze-Makuch, a professor with WSU and the Technical University in Berlin, as per a university release. ¡°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.¡±

The far-off observation

For the study, Schulze-Makuch, a geobiologist with expertise in planetary habitability, teamed up with astronomers Ren¨¦ Heller and Edward Guinan. The goal was to identify planets that meet the superhabitability criteria among the 4,500 known exoplanets beyond our solar system.

The researchers looked at a number of criterias for the same. Looking at the planet-star co-relation first, the researchers noted that host star¡¯s with a lifespan larger than our Sun would allow more time for complex life forms to grow on the orbiting planets.

Next, they identified planets with an age of between 5 billion to 8 billion years. Planets older than that tend to exhaust their geothermal heat and lack protective geomagnetic fields. Earth is currently around 4.5 billion years old.

The study also explains that a planet with a size slightly larger than the Earth should have more habitable land. Similarly, a larger planet with a larger mass will have a stronger gravity to retain its atmosphere over a longer time period than Earth.

(Representative Image: NASA)

Similarly, scientists note in the study that the ideal conditions for a planet to be superhabitable will be the presence of more water in the form of moisture, clouds and humidity and a slightly warmer temperature than Earth for better conditions for life to thrive.

Of course, these valid criterias for habitability of a planet do not mean these planets definitely have life. In fact, among the top 24 candidates short-listed by the researchers, none met all these criteria for superhabitable planets. One of them, however, has four of these critical characteristics, making it ¡°more habitable¡± than Earth.

¡°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."