When you title a research paper “In Search for a Planet Better than Earth,” you’re not messing around. Earth, the only place we know for sure hosts life, sets a high bar for all other planets.
Washington State University (WSU) geobiologist Dirk Schulze-Makuch led a study published in the journal Astrobiology last month. The paper identifies two dozen exoplanets (planets located outside our solar system) that could be “superhabitable” worlds more suitable for life than our own.
The researchers created a set of criteria for planets to qualify as potentially superhabitable. This list includes an age of between 5 billion and 8 billions years old (Earth is about 4.5 billion years old) and a location within a star’s habitable zone where liquid water could exist. They also looked for long-lived stars that are cooler than our sun.
Rather than focus on Earth clones, the team searched for planets that are more massive than our own. “One that is about 1.5 times Earth’s mass would be expected to retain its interior heating through radioactive decay longer and would also have a stronger gravity to retain an atmosphere over a longer time period,” said WSU in a statement on Monday
The team applied the criteria to 4,500 known exoplanets and identified 24 that came the closest to fitting the bill. None ticked all of the boxes, but they hint at the possibilities for life-friendly worlds beyond our own.
There are a lot of unknowns when it comes to these potential paradises. “Habitability does not mean these planets definitely have life, merely the conditions that would be conducive to life,” WSU said. An even bigger issue is the candidates are all over 100 light-years away, too far to ever reach.
What’s useful here is the criteria for planets that may not look exactly like Earth, but could be even more awesome locations for life. This could help us direct the resources of next-generation space telescopes like.
“We have to focus on certain planets that have the most promising conditions for complex life,” Schulze-Makuch said. “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.”