A recent study indicates that even the harshest exoplanets may not be completely uninhabitable.

Slightly larger than Earth, the exoplanet LHS 3844b orbits a small red dwarf star, LHS 3884, located about 48.5 light-years away. Unlike Earth, it has no sunrise or sunset because it is tidally locked—one side permanently faces its star while the other remains in constant darkness. This creates extreme conditions: the sun-facing side is intensely hot, while the dark side approaches near-absolute zero temperatures, where molecular motion almost ceases.

At first glance, such a planet appears utterly uninhabitable, but scientists are starting to challenge that view.

Figure 1. Tidally Locked Exoplanet with Potential Subsurface Habitability

Daisuke Noto, a postdoctoral researcher in Hugo Ulloa’s Penn GEFLOW Lab at the University of Pennsylvania, has been exploring whether these extreme conditions necessarily preclude life. “Seeing the scorching day-side temperatures of 1,000–2,000 Kelvin and the night side nearing absolute zero might make one assume these exoplanets are too hostile for life. But,” Noto explains, “life could still adapt.” Figure 1 shows Tidally Locked Exoplanet with Potential Subsurface Habitability.

Reevaluating Life Potential on Extreme Planets

To investigate this, Noto and his collaborators from the Japan Agency for Marine-Earth Science and Technology and Hokkaido University reported in Nature Communications that such exoplanets might actually support life. They suggest that tidal locking can help create locally moderate temperatures by redistributing heat across the surface.

Noto notes that this research challenges conventional ideas about the limits of habitability and points out that similar experimental methods are being applied to study processes deep within Earth.

He adds that planets with permanent day and night sides are far more common than Earth-like worlds with regular day-night cycles. “Many celestial bodies—moons and planets orbiting close to their stars—are tidally locked,” Noto explains. “This means their rotation and orbit rates align, so we see only one side, like we do with our Moon.”

Recreating Alien Planet Interiors in the Laboratory

The planet’s permanent day-night alignment creates extreme temperature differences, and Noto’s research examines how this affects the mantle—the thick rocky layer between a planet’s crust and core.

“Building a full exoplanet in the lab wasn’t feasible,” Noto admits. Instead, his team used a rectangular tank filled with viscous glycerol and thermochromic liquid crystals, which change color with temperature. This approach builds on a long-standing tradition of lab models that study how heat and material properties drive convection in slow-moving systems, from Earth’s interior to hypothetical alien worlds.

Unlike weather or ocean currents, which are strongly influenced by rotation and gravity, mantle convection is primarily driven by temperature and density differences. To simulate this, the team controlled heating and cooling along the tank’s edges using four thermostats, generating temperature gradients analogous to those between a planet’s day side, night side, surface, and deep interior.

The Rhythms of a Planet

The experiments revealed a stable, repeating flow pattern: hot material rises on the day side, travels across the surface, cools and sinks on the night side, then returns along the bottom—forming a continuous circulation loop, like a steady planetary “heartbeat.”

“It’s not chaotic like Earth’s mantle,” Noto notes. “It’s slow, steady, and predictable. Kind of boring, but in a good way.”

Occasionally, the flow generated plume-like structures from the heated base. Unlike Earth’s hotspots, which shift over time in locations like Hawaii or Iceland, these plumes remained fixed.

The model also produced Nusselt numbers—a measure of heat transfer—similar to Earth’s, suggesting that some exoplanets could sustain localized geothermal environments, especially in mid-latitude regions where temperatures are less extreme.

Hidden Insights Beneath the Surface

Noto suggests that the planet’s large-scale mantle circulation could also affect its liquid core, potentially generating magnetic fields unlike Earth’s familiar dipole structure.

“That’s beyond what we could test in this experiment,” he notes, “but it points to an exciting avenue for future research.”

He and Ulloa are continuing to expand their studies using similar lab models to explore a range of geophysical systems [1]. Previous work has investigated how mass and heat move in confined environments, shedding light on fluid dynamics in hydrothermal systems.

“We plan to extend these experimental methods to study various planetary and terrestrial systems. The possibilities are, quite literally, out of this world,” Noto says.

Reference:

1. https://scitechdaily.com/scientists-say-this-hellish-day-night-planet-may-support-life/

Cite this article:

Janani R (2026), Scientists Suggest This Extreme “Day-Night” Planet Could Potentially Harbor Life, AnaTechMaz, pp.813