After studying more than 4,500 exoplanets, experts have listed the 24 best candidates for being “superhabitable”. By being characterized as “superhabitable”, these planets could be a bit warmer, slightly bigger, wetter, and older than Earth which means that they are possibly more habitable than our own planet. And when orbiting a star that is a bit cooler and lives longer than our own sun, that could mean that these planets contain better conditions for any possible life.
A team of experts that was led by Washington State University studied these exoplanets that are all located more than 100 light-years away from us. Dirk Schulze-Makuch, who is a geobiologist and the lead author of the study, as well as several astronomers, conducted the research and said that while these planets are considered to be “superhabitable”, it doesn’t mean that they do contain any type of life as much more research needs to be conducted, specifically on their atmospheres.
In order to study their atmospheres, they will need much more powerful technology such as NASA’s James Webb Telescope, the LUVIOR space observatory, and ESA’s PLATO that will hopefully be able to gather more information regarding these exoplanets.
“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,” Schulze-Makuch explained. Based on their orbiting distance from their host star, as well as their size and surface temperature, the experts have predicted that they could also contain liquid water.
Since our sun’s total lifespan is less than 10 billion years (called a G star), scientists looked for G stars as well as K stars which are smaller, dimmer, and cooler but live much longer than our own sun with life spans of between 20 billion and 70 billion years. This means that the planets orbiting them could also be much older, ultimately giving them a lot more time for any potential life to evolve.
Additionally, if a planet is a bit bigger than Earth, it should have more land available for any possible life to thrive. And if they are slightly warmer than Earth (about 8 degrees Fahrenheit warmer) and have more moisture in the air (perhaps clouds and humidity), this would allow for a much greater chance of having life. For comparison, there is a lot more variety of life living in our tropical rain forests than in dry, cooler areas on our planet.
Schulze-Makuch finished off by stating, “It's sometimes difficult to convey this principle of superhabitable planets because we think we have the best planet,” adding, “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.”
While these planets are way too far for us to visit (at least for now), it gives scientists a better understanding of hopefully finding more potential “superhabitable” planets in other locations in the universe and perhaps even closer to Earth. Their research was published in the journal Astrobiology and can be read in full here.