Better Than Earth? Scientists Identify 24 ‘Superhabitable’ Planets
Our observations of distant stars have revealed more than 4,000 exoplanets, and some of them have been labeled as potentially habitable. That doesn’t mean there’s anyone living there, but it’s possible. It may also be possible that there are so-called “superhabitable planets” in the cosmos where the chances are higher. A new analysis published in the journal Astrobiology seeks to identify these worlds, and the researchers say we might have already detected 24 of them.
When we talk about habitable planets, that usually means worlds that are very much like Earth — the kind of place where there’s liquid water and an atmosphere. A human, plopped down on such a world, would not immediately curl up and die. A superhabitable planet isn’t just one that’s better for human life. The team led by astrobiologist Dirk Schulze-Makuch from the Technical University Berlin defines a superhabitable planet as one that is even more likely than Earth to have life. The research argues that these are the worlds we should focus on when hunting for aliens.
We only have this one living ecosystem on which to base our assumptions about what’s “habitable.” It’s possible that Earth isn’t anything special as a home for life. Perhaps an alien observing Earth from a great distance would be surprised intelligence could evolve on such an unsuitable hunk of rock. The authors note that restraining our anthropocentric view of the universe could be vital to finding life among the stars.
So, what makes a planet superhabitable? We know that Earth’s warmer regions have greater biological diversity, so a planet somewhat warmer than Earth could host more life. That might not make it very comfortable for humans, but that’s not the point. Likewise, the team looked for exoplanets that are about 1.5 times as massive as our home planet. These worlds are more likely to have a dense atmosphere, and there would be more surface area for life to occupy.
The star an exoplanet orbit is also an important factor. The sun is a yellow dwarf, and it does a good job of keeping Earth livable, but maybe this isn’t the best kind of star for life. The sun has a lifespan of about nine billion years, and we’ve only got another billion years or so before it heats up and boils Earth like an egg. If you’re playing the odds, planets that orbit longer-lived stars like orange dwarfs could have a higher chance of hosting life.
The team surveyed the known exoplanet catalog and found 24 worlds that might qualify as superhabitable. One such planet is KOI 5715.01, which is 3,000 light-years away. It’s 1.8 times Earth’s mass and orbits an orange dwarf. However, none of the exoplanets cited in the paper are within 100 light-years. The hunt for superhabitable worlds may be at an impasse until more advanced instruments like the James Webb Space Telescope come online.