Researchers from the US and Germany found 24 ‘super-habitable’ planets, where life had more opportunities to evolve into higher forms than on Earth
The search for exoplanets, planets outside the Solar System, is being one of the great challenges for astronomers in recent times, although it is not proving an easy mission.
However, a hopeful piece of information has been provided by a team of scientists led by geobiologist Dirk Schulze-Makuch of the Washington State University). Schulze-Makuch and his team have identified 24 exoplanets that could be more favorable to life than Earth itself thanks to data from the Kepler mission.
Of the more than 4,000 exoplanets found so far, some have been considered habitable, although this is a somewhat misleading term.
“Habitable”, a misleading term
It’s not that we’re on a planet where humans can get there and start living immediately, but what we are having here is rocky planet that’s in the right orbital region around its star, where the temperature is moderate enough for liquid water to exist on its surface without freezing or boiling.
To get an idea, following these criteria, apart from Earth, our Solar System is home to two other potentially habitable planets: Venus and Mars.
Now, astronomers from the American university, in a study published in the scientific journal ‘Astrobiology‘, have refined the search a bit and have located 24 candidate exoplanets that are not only habitable but potentially more habitable than our planet.
They are located more than 100 light-years from the Sun and were selected because they have some properties that could make them more capable of supporting life.
In this selection, the star (or sun) to which they orbit takes great importance. The usual assumption is that an orbit around a G-type star, like the Sun, would be the best place to find a habitable planet.
However, such stars only have a lifespan of about eight to ten billion years and it took four billion for something other than the simplest life to evolve on Earth.
A K-type dwarf star, on the other hand, would be colder and less massive than the Sun but would have a lifespan of up to 70 billion years, allowing a much longer time for life to emerge and develop.
Another couple of factors would be size and mass. Part of the reason the Earth is habitable is that it is large enough to be geologically active, giving it a protective magnetic field, and it has enough gravity to retain an atmosphere.
According to the team, if a planet would be ten per cent larger, it would have more surface area to live on. If it were 1.5 times more massive than Earth, its interior would retain more heat from radioactive decay, it would remain active longer, and it would retain its atmosphere longer.
Also, if a world is five degrees Celsius warmer than Earth and had more water, it would enjoy the biodiversity of a tropical rainforest across much of the planet.
NASA’s Transit Exoplanet Surveying Satellite (TESS) collects hundreds of thousands of snapshots of the sky, each containing signals from possible planets. You can help astronomers identify them in Planet Patrol, a new #citizenscience project! https://t.co/CdE6bv1H2u pic.twitter.com/R3gLQePWso
— NASA Goddard (@NASAGoddard) October 3, 2020
The team says that none of the 24 planets found has all of these characteristics, but one has four of the critical factors. In any case, the 24 could be the focus of later telescopic studies.
“Sometimes it is difficult to convey this principle of super-habitable planets because we believe we have the best planet,” Schulze-Makuch explains in statements collected by New Atlas. “We have a large number of complex and diverse lifestyles and many that can survive in extreme environments. It’s good to have an adaptable life, but that doesn’t mean we have the best of everything.”
“It’s sometimes difficult to convey this principle of super-habitable planets because we think we have the best planet,” explains Schulze-Makuch in statements collected by New Atlas. “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.”