- Superhabitable planets are celestial bodies that might offer even better conditions for life than Earth.
- Researchers are exploring planets that go beyond Earth-like conditions to broaden the search for potential habitats.
- Orange dwarf stars, more common than yellow dwarfs like our sun, might provide longer lifetimes for planets to develop life.
- Planets that are slightly larger than Earth and slightly warmer could be more conducive to biodiversity.
- Worlds with smaller continents and shallower waters could also be more habitable.
In the quest to discover new potential homes for humanity, scientists are expanding their horizons beyond Earth-like planets to consider the intriguing concept of “superhabitable” worlds. While Earth is currently the only known planet teeming with life, researchers are contemplating the existence of planets that could surpass our home in terms of their suitability for life.
Astrobiologists like Dirk Schulze-Makuch, affiliated with Washington State University and the Technical University of Berlin, argue that our search for habitable exoplanets has been overly focused on finding Earth-like replicas. Schulze-Makuch contends that this “anthropocentric and geocentric” approach may blind us to the myriad possibilities of exobiology.
To uncover these potentially superhabitable exoplanets, Schulze-Makuch’s team delved into the Kepler Object of Interest Exoplanet Archive, concentrating on 4,500 planetary systems likely to host rocky planets within their stars’ habitable zones. Their findings, detailed in a 2020 paper in the journal Astrobiology, broadened the search criteria beyond planets orbiting sun-like stars to include those circling cooler, dimmer orange dwarf stars.
Surprisingly, orange dwarf stars, which are more common than sun-like stars in the Milky Way, have lifetimes estimated at 20 billion to 70 billion years, significantly longer than our sun’s lifespan of under 10 billion years. This extended timeline could provide planets within their habitable zones with ample time to evolve life and foster biodiversity.
The researchers proposed that the ideal age for a superhabitable planet might range from 5 billion to 8 billion years, based on Earth’s estimated age of 4.5 billion years. Additionally, they considered the size and mass of a planet as factors influencing its potential to support life. Larger rocky planets could offer more habitable surface area and a more stable atmosphere, while those slightly warmer than Earth might boast larger tropical zones, encouraging biodiversity.
Moreover, planets with Earth’s landmass but divided into smaller continents could be more habitable, as vast landmasses often create inhospitable deserts far from oceans. Additionally, planets with shallower waters, like Earth’s, could potentially support more diverse life compared to planets dominated by deep oceans.
Among their findings, the researchers identified 24 potentially superhabitable planets, with KOI 5715.01 meeting at least two of their criteria. Located approximately 2,965 light-years away, this planet orbits an orange dwarf star and possesses attributes that make it a strong contender for superhabitability.
Another intriguing candidate is KOI 5554.01, which orbits a yellow dwarf star about 700 light-years from Earth. This planet, approximately 6.5 billion years old and similar in size to Earth, boasts an appealing average surface temperature of about 27 degrees Celsius (80 degrees Fahrenheit).
Although these superhabitable candidates are located more than 100 light-years away, future spacecraft like the James Webb Space Telescope, NASA’s LUVOIR mission, and the European Space Agency’s PLATO telescope could provide insights into these distant worlds.
Schulze-Makuch emphasizes that the search for superhabitable planets does not guarantee the presence of life. While a planet may possess ideal conditions, it may remain uninhabited. Nevertheless, the exploration of such planets expands our understanding of the vast possibilities for life beyond Earth.