A planet suitable for human habitation may be an ocean world?

More than 70% of our planet is covered in water, and we tend to think a lot. A new study shows that our world is special in this respect, with most habitable planets occupied by oceans that consume more than 90 percent of its surface area. This may have been good for primitive sea creatures, but not for aspiring civilizations.

(Image: Interstellar)

A new study published in the Monthly Notices of the Royal Astronomical Society suggests that most habitable planets are wet. Like, very moist. Fergus Simpson, an astronomer at the Institute of Astronomical Sciences at the University of Barcelona, ??used computer models to find that habitable exoplanets, at least simulated exoplanets, tend to be flooded with water, and in most cases they account for 90% or more of total surface area.

The discovery suggests that Earth is unique in the universe's cosmology for its vast landmass, and that our planetary twin may be harder to find than we thought. What's more, it might explain why we've never been exposed to extraterrestrial intelligence - a conclusion that feeds into the rare earth hypothesis (REE hypothesis), which states that Earth-like planets containing complex life are extremely rare in the universe.

This USGS image shows the size of a sphere containing all of Earth's water, compared to the size of Earth. It may not seem like much, but our planet is relatively flat, so it takes a lot of time. Image: USGS)

As Simpson points out in his new study, a planet must achieve a certain balance if it is to accommodate both vast landmasses and vast oceans. Factors that control this balance include the amount of water on the planet's surface, the space available to store the planet, and the presence of dynamic terrain features ranging from broad ocean basins to mountain ranges. If the oceans are relatively shallow and the land is low in elevation, the excess water will consume the vast majority of the Earth's surface. On Earth, global topography keeps approximately 29% of the planet's surface area above water. This ratio has remained relatively stable over time, allowing for the emergence of complex land animals such as ourselves.

At least in theory. Simpson's model is not based on observations of real exoplanets, but on best guesses about planet formation and how much water we could expect to find in these hypothetical worlds.

Astrophysicist Sean N. Raymond, who was not involved in the study, said in an interview with Gizmodo: "I have some doubts about this paper."? "I found out The study of extrapolating from N = 1 is interesting, but difficult to interpret, and there are many unresolved but relevant questions in this case. ”

Most of the water on Earth passes through asteroids. Comet.

Indeed, the question of how planets obtain water remains a matter of debate. The common theory is that most of Earth's water was transported by asteroids and comets. If so, it would be nearly impossible to predict the amount of water on any given planet. In order for us to know for sure, we need to know the average amount of water delivered to a planet our size and location. But every star system is different, and they have different amounts of asteroids, comets, and water, not to mention that neighboring planets are also sucking water from the heavens.

"In the 'classical model' of Earth's planet formation, water transport to Earth is very [random], so it's conceivable that an alternate Earth would have had ten times more water," Raymond said. "But in our new model, much less water is delivered, but the delivery is more reliable." What Raymond is talking about is the observation that the inner solar system is water-poor while the outer solar system is rich in water.

"Water worlds will always be beyond what we call the 'snow line,'" Adam Sarafian, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences, told Gizmodo. "The snow line existed in the early solar system before the planets formed. Beyond the boundary, water could have condensed like ice, so that bodies of water in the outer solar system were water-rich and water-poor bodies in the inner solar system. Therefore, we would expect water worlds to exist in the outer solar system , while relatively dry planets would exist in the inner solar system.

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Sarafian, who was not involved in the new study, is currently trying to figure out why Earth has so much water and when it got here. "Recently," Sarafian said. Evidence suggests that the inner solar system was likely filled with large amounts of water very early on, so Mars may have looked like Earth (partly a water world) shortly after its formation. "One advantage of looking at planets close to the sun is that this does not allow them to become water worlds due to the presence of the snow line, as the sun provides a lot of the energy for life and can provide liquid water on the ground because of the opposition to ice." ”

Sarafian sees Simpson’s new study as part of a larger conversation that is largely about speculation about finding the best places to live.< /p>

Waterworld is a movie, but at least it's scientifically correct.

But there are other factors to consider besides how the Earth gets its water, such as the deep sea vs. How interactions between Earth's mantle regulate the depth of its oceans. For example, Earth may be unique in that it has unusually deep water basins. More research is needed to determine whether this is the case. > Simpson himself considered some of these effects and asked his test models to account for deep water circulation, erosion, and sedimentation processes (i.e., the processes that add sediment, soil, and rock to land). Still, he found that at large. In most cases, water is the dominant surface feature. Interestingly, he found that planets with smaller oceans have mostly desert land, and that planets as large as Earth are almost guaranteed to be water worlds. >Simpson told Gizmodo: "Larger planets are thought to be more prone to flooding, for two reasons. "One is that if they have the same composition (mass percentage of water), then their oceans will be deeper." The second reason is that their higher surface gravity makes them less susceptible to such large surface perturbations [dynamic topological features]. ”

If Simpson’s conclusion is correct, it means our planet already has a good balance between land and ocean—an observation that may help explain why our Civilization emerged on Earth (although some would argue that it's unlikely that a high-tech, industrial-scale civilization could develop on a water-consumed world). In fact, Simpson says, this is where artificial selection effects are at work. The idea that Earth is a weird planet, because if it wasn't a weird planet, we wouldn't see it here

The problem with the human principle, thankfully, is that it's not testable. , this new water world theory is.

The exciting aspect is that we may not be too far away from measuring the composition of the atmospheres of Earth's exoplanets. "Indeed, with the next generation of telescopes, including those in space, we will be able to scan the atmospheres of exoplanets to determine how much water there might be on the surface.

Additionally, scientists will need to figure out All the ways and reasons why our planet is a weirdo. Before that, let's celebrate the fact that Earth is the weirdo of the galaxy.