Habitable planets likely to be cold, dry ‘pale yellow dots’

Remember all the habitable planets we saw in science fiction movies? There is Winter Hoth, for example, and extremely hot sand dunes. people in Interstellar He visited an ocean world and a desolate rocky world. Despite all their differences, these places were still what they claimed Star Trek M-class habitable worlds. Sure, they weren’t all Earth-like, but this made them sensationally alien to the life forms they supported. In the real universe, it seems that space worlds are not quite like ours could be the norm. Earth could be truly strange world.

According to a pair of researchers in Europe, it’s possible that pale blue dots like ours are not as common. Alternatively, many habitable planets could be much cooler and drier than our own. Moreover, these places may look more like pale yellow dots, because they may not contain the same amount of water.

Planetary scientists Tilman Spoon and Dennis Hoeing have modeled potential exoplanets to see how the evolution of continents and planetary water cycles might shape the evolution of habitable worlds. They concluded that the probability of covering most of the planets with Earth is about 80%. This means that they will have mostly continental landscapes. Another 20 percent of the habitable worlds would likely be primarily surrounding. A small percentage (less than one percent) will be similar to the water distribution on Earth.

Earth-type habitable planets can evolve in three scenarios of the Earth/ocean distribution: covered by land, oceans, or an equal mixture of the two.  A planet covered with Earth is the most likely scenario (about 80%), while Earth
Earth-type habitable planets can evolve in three scenarios of the Earth/ocean distribution: covered by land, oceans, or an equal mixture of the two. An Earth-covered planet is the most likely scenario (about 80%), while an “equal mixture” Earth (less than 1% chance) is more distinct than previously thought. Modeling shows that the odds of three very different types of terrestrial planets vary widely, affecting their climate and habitability. Credit: Europlanet 2024 RI/T. Present.

“We earthlings enjoy a balance between the land and ocean regions of our home planet,” said Spoon, executive director of the International Space Science Institute in Berne, Switzerland. “It’s tempting to assume that a second Earth will be just like our own, but our modeling results suggest that it is not That may be the case.”

Differences in habitable planets

So why are habitable planets different from Carl Sagan’s “pale blue dot”? The “look and feel” of each exoplanet depends on different characteristics. These range from its structure to the star it orbits. On Earth, the growth of continents through volcanic activity and their erosion by weathering is more or less balanced. Here life thrives. Many plants, for example, do well in the ground. This is where they can reach the friendly sun to carry out photosynthesis. This process allows them to move energy and nutrients through the food chain. Life also thrives in the oceans and provides a huge amount of water that enhances precipitation. Oceanic water resources prevent the Earth’s current climate from becoming too dry.

According to the researchers, geology also plays an important role. The main driver of plate tectonics is internal heat. “This drives geological activity, such as earthquakes, volcanoes, and mountain formation, and leads to the growth of continents,” Spoon said. “Earth erosion is part of a series of cycles that exchange water between the atmosphere and the interior. Our numerical models of how these cycles interact show that today’s Earth may be an exceptional planet and that Earth’s mass balance may be unstable over billions of years. While all the planets that designed to be considered habitable, its fauna and flora might be quite different.”

Not all life-bearing planets are alike

The good news here is that the land-to-ocean ratios allow for a very broad definition of the term “habitable”. The ocean world, with less than 10 percent of the land, for example, could turn out to be a humid and warm planet. It may be similar to Earth having recovered from the impact that helped kill the dinosaurs. This makes sense because the models that Spohn and Höning worked on show that average surface temperatures on these worlds would be more like Earth’s temperatures. Such a world could be teeming with life forms.

Planets with less than 30 percent of the oceans will have cooler temperatures and drier climates. They may have cold deserts and maybe some ice sheets. We know from similar regions here on Earth that life can thrive in such environments.

Here is another interesting idea. The Earth we know today is different from what it was in various other phases of its history. For example, there can be worlds with conditions similar to those that our planet experienced during the ice ages. Life flourished here during those times, and such a world was completely habitable. Interestingly, people who lived on our planet during that time 10,000 years ago will find these places comfortable and familiar.

The number of known confirmed exoplanets now exceeds 5,000. Some are habitable. Others are not. some are super-terrestrial beings, others are giant gas giants. But it’s only a matter of time before planetary scientists find the palest point of the world. It’s interesting to think that whether it’s blue or yellow, it can be welcoming to life.

for more information

Other Earth-like exoplanets are unlikely to be another “pale blue dot”
Spohn, T. and Hoening, D: Land/Ocean Surface Diversity on Earth-Like Planets (Exo): Implications for Habitability, Europlanet Science Congress 2022, Granada, Spain, Sep 18–23 2022, EPSC2022-506, 2022.