Most Extrasolar Earths Are Cold, Dry And Land-Dominated, Says New Research

New computer models of more than a thousand potential terrestrial planets shockingly indicate that less than one percent would have the same land-ocean dichotomy as our own pale blue dot. That’s according to a new paper presented this afternoon at the Europlanet Science Congress 2022 (EPSC) here in Granada, Spain.

The research co-authored by the Swiss-German team of Tilman Spohn and Dennis Hoening shows how the evolution and cycles of continents and water could shape the development of terrestrial exoplanets, reports EPSC. Results from their models suggest that planets have approximately an 80 percent probability of being mostly covered by land, with almost 20 percent likely to be mainly oceanic worlds, ESPC notes. Barely one percent of the computer models’ results had an earthlike distribution of land and water.

If you’re going to look for a second Earth, you should maybe expect a planet with maybe a brownish color palette that is largely covered with land mass, geophysicist Tilman Spohn, executive director of the International Space Science Institute in Bern, Switzerland, noted in his presentation.

The paper on which the oral presentation was based has been submitted to the journal Astrobiology and the authors note that these planets would all be considered habitable, but their fauna and flora may be quite different.

Here on Earth, rivers, oceans, rivers and lakes make up 70 percent of the surface.

“The news from this paper is that our planet is apparently atypical; I was surprised,” Spohn told me here in Granada.

The researchers’ models started with initial conditions that included everything they knew about how our own planet’s continents formed and evolved. They found that continental worlds, with less than 30 percent oceans, are likely to dominate the galaxy. Cool, deserts might occupy in the inner parts of the landmasses and resemble earth during the last ice age, the EPSC notes. In contrast, ocean worlds with less than 20 percent land would likely be moist and warm.

And if Spohn had to guess how many truly earthlike planets are in our galaxy?

You would only find one earth-like planet for every 10,000 rocky planets, something in that ballpark, says Spohn.

As for how close the nearest true Earth analog might lie?

About a hundred light years, says Spohn.

Does Spohn see intelligent life being able to develop on either an ocean world or a land dominated world?

Possibly, these two extreme plans that I’m describing also would have plate tectonics, says Spohn.

Plate tectonics is the geophysical theory that Earth’s crust is made up of large independently moving lithospheric plates that float atop Earth’s mantle. Constantly in motion, they are thought to have enabled a stable climate here on Earth via carbon recycling.

But even though Spohn has given his model planets plate tectonics, he does see the larger benefits of living on a planet that has a more evenly balanced land-ocean makeup. Thus, he admits that the chances of finding intelligent life on such a heavily land-dominated extrasolar earth, are probably smaller than then on our own planet.

Yet we too may end up land dominated. Spohn says that because Earth’s continents are continuously growing, in a billion years, our own planet may be more land-dominated than water-dominated.