These Earth-like planets could be our new homes

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Representational Image
Representational Image

New Delhi : Imagine a life outside the blue planet, Earth, where there is no sunrise, no sunset! Well, we cannot but astronomers have some different words to say. They believe that most of the planets in our galaxy that have Earth-like temperatures may be suitable for humanity. Because their orbital period is the same as their period of rotation, these planets will always present the same face to their sun, just like we see the moon as it orbits the Earth.

For instance, astronomers recently discovered seven Earth-size planets in the habitable zone of the TRAPPIST-1 system, all of which are likely to be tidally locked. 

However, talking about living in other planets means a situation mostly experienced in science-fiction films. But, scientists are learning enough about the dynamics of tidally locked worlds to start to understand how they would work, and what kind of civilization we could build there.

Now, the basic question that strikes every minds are Where would humans settle on a tidally locked planet? When I started working on my book, the clearest answer appeared to be the terminator, the strip of twilight between the dayside and the nightside. “That might be the Goldilocks zone,” neither too hot nor too cold, but stuck “between eternal dusk and eternal dawn,” says Daniel Angerhausen, an astrophysicist at the Center for Space and Habitability at Bern University.

In the terminator zone, Angerhausen suggests, humans might be able to generate geothermal energy, using cold water from the nightside and hot water from the dayside in “some kind of thermal reactor.”

Ludmila Carone of the Max Planck Institute for Astronomy mentions that to have access to liquid water on a tidally locked world, you need a system to cool down the dayside and heat up the nightside. Else, all the liquid might become tied up in ice on the nightside, or worse yet, the atmosphere itself could get frozen in the dark.

“The habitability of these planets hinges very strongly on how well you can transport heat,” Carone says

Even a relatively modest temperature differential (say, 50 degrees Fahrenheit) between the two sides could make these planets harder to live on. A comfortably mild climate on the dayside might still leave the nightside cold enough to freeze water, according to Laura Kreidberg, a junior fellow at Harvard University who studies the atmospheres of exoplanets. “Could all the planet’s water freeze out on the nightside? We don’t yet know,” she says. Ocean currents could help transport heat, too, but those effects depend on how much water the planet has to begin with and where the continents are.

The biggest challenge for humans living in a tidally locked world, says Paradise, could be the very different sky. If they lived on the dayside, they might “lose all knowledge of the universe,” because they would never see the stars. Their perception of the passage of time would also be altered, because “nothing in the sky would ever change.”