An unusual planet located about 48.5 light-years from Earth may seem far too extreme for life.
One side is permanently exposed to intense heat, while the other remains in endless darkness and freezing cold.
Yet new research suggests that this harsh world might still contain regions where life could survive.
The study, published in Nature Communications, focuses on the rocky exoplanet LHS 3844b. It orbits a small, cool red dwarf star called LHS 3844.
Because the planet is so close to its star, it is “tidally locked.” This means it rotates at exactly the same speed that it orbits its star, just as our Moon always shows the same face to Earth.
As a result, one side of the planet experiences constant daylight and extreme temperatures that can reach between 1,000 and 2,000 Kelvin.
The opposite side never sees sunlight and could be close to absolute zero, the coldest temperature possible.
At first glance, such conditions seem impossible for life. However, researchers from the University of Pennsylvania, the Japan Agency for Marine-Earth Science and Technology, and Hokkaido University wanted to investigate what happens beneath the planet’s surface.
Instead of focusing on the atmosphere, they studied the planet’s mantle, the thick layer of hot rock between the crust and the core. The movement of this rocky material plays an important role in carrying heat around a planet.
Since building a real exoplanet in the laboratory is impossible, the team created a clever experiment using a small tank filled with thick glycerol liquid.
They added special temperature-sensitive crystals that changed color as the liquid warmed or cooled. By heating one side of the tank and cooling the other, they recreated the temperature difference between the planet’s permanent day and night sides.
The experiment revealed a surprisingly simple pattern. Hot material rose beneath the hot side of the planet, slowly flowed across the upper part of the mantle, cooled as it reached the dark side, then sank and returned beneath the surface. This created one large, steady circulation loop that continuously moved heat from the hot side toward the cold side.
Unlike Earth’s mantle, which is constantly changing because of moving tectonic plates, this circulation remained stable and predictable.
The researchers also observed rising columns of hot material, known as mantle plumes. On Earth, these plumes move over time and create volcanic hotspots such as Hawaii and Iceland. On the simulated exoplanet, however, the plumes stayed fixed beneath the same location because the planet always faces its star in the same direction.
This steady heat flow could create areas between the hot and cold sides where temperatures are much more moderate. These “twilight zones” may offer conditions that are far more suitable for life than scientists once believed.
The study also suggests that this unusual circulation inside the planet could influence its liquid core and possibly produce a magnetic field, although more research is needed to test this idea.
The researchers believe their findings show that tidally locked planets should not automatically be ruled out as places where life might exist.
As astronomers continue discovering rocky planets around nearby stars, studies like this may help identify which distant worlds are the most promising places to search for signs of life beyond our solar system.
