The existence of plate tectonics is thought to have been a major factor in the formation of our planet and the evolution of life. Mars and Venus do not experience such crustal plate movements, but the differences between the worlds are clear.
Many varied environments have also been encountered during the exploration of exoplanets. Many of these new alien worlds appear to have significant internal heating and therefore no plate movements.
Instead, a new study reveals that these ‘Ignan Earths’ are more likely to have heat pipes that channel magma to the surface. The likely result is a surface temperature similar to that of Earth during its hottest period, when liquid water began to form.
Plate tectonics explains the movement and interaction of the Earth’s upper layers. More precisely, the lithosphere consists of the crust and the upper layer of the mantle.
It is divided into a number of pieces known as tectonic plates, which float around on the semi-liquid layer below, the asthenosphere. Where the plates meet, various geological features form, such as mountains, volcanoes and trenches.
The process has been a crucial factor in the evolution of life on our planet. The shifting of land masses has created new habitats and isolated populations, allowing individual ecosystems to emerge.
Plate collisions led to the development of mountain ranges that influenced weather patterns and climate.
Volcanic activity, driven by plate movements, led to soils becoming fertile, plant life flourishing and gases such as carbon dioxide being released into the atmosphere, helping the planet regulate its climate. It has truly been a crucial process in the evolution of our planet.
In some ways, the process also prevents a planet’s internal environment from overheating. There is a school of thought that if Earth did not have such plate motion, it might be too warm internally for a stable environment to develop. This was the subject of Matthew Reinhold and Laura Schaefer’s article published in Advancing Earth and Space Sciences.
They explored the likelihood that such a world could have so much internal heating that it would instead resemble bodies like Jupiter’s moon Io. Here we see intense levels of volcanism with lava violently erupting hundreds of kilometers into the atmosphere that is full of toxic gases.
It’s not just a lack of plate tectonics that can lead to high levels of internal heating. Tidal effects can cause worlds to have one face that continually points toward the sun, creating a wide range of surface temperatures.
Collectively, these worlds are casually known as those of Ignan Earth and they are the purpose of the article to investigate whether they are habitable. Exploring the geology of the bodies in our solar system provides great insight.
The team shows that worlds with high internal temperatures are likely to develop a solid mantle. The crust will therefore remain largely stable, with the only likely activity being heat pipe tectonics, where some of the internal heat is transferred to the surface, for example by volcanic activity.
The team was able to model the likely range of surface temperatures based on a number of different types of worlds and found that, contrary to previous expectations, a wide range of internal heating rates could well lead to worlds where the environment is conducive to habitability.
