Jerusalem, 22 January, 2026 (TPS-IL) — Life beyond Earth may exist in far stranger places than scientists once thought, a new study suggests. Worlds previously dismissed as too hot, too cold, or permanently dark could still host liquid water—the key ingredient for life.
For decades, astronomers have searched for planets in the “habitable zone,” a narrow ring around a star where temperatures allow water to remain liquid. Within the solar system, the habitable zone extends roughly from the orbit of Earth to that of Mars. Yet many exoplanets now being discovered do not fit neatly into this framework. Some orbit stars very different from the sun, while others lie far closer or farther from their star than the traditional habitable zone allows.
A new study by Prof. Amri Wandel, an astrophysicist at the Hebrew University, questions the assumptions behind this classical definition. Published in the peer-reviewed The Astrophysical Journal, the research focuses on tidally locked planets — worlds that always show the same face to their star. One side experiences permanent daylight, while the other remains in eternal night. Until now, the dark side was assumed to be frozen, making it unlikely to support water or life.
Wandel’s analysis suggests otherwise. Using a model that tracks temperatures across a tidally locked planet, the study finds that heat from the day side can flow to the night side, keeping some regions warm enough for liquid water. This could occur even on planets orbiting very close to cooler stars, such as M- and K-dwarfs, previously thought too hot for surface water. “Our results show that liquid water can exist on the dark side of tidally locked planets,” Wandel said. “This expands the environments where life-friendly conditions may exist, well beyond what the traditional habitable zone predicts.”
The research also extends the habitable zone outward. On planets far from their star, once considered too cold, liquid water could survive beneath thick ice sheets in subglacial or intraglacial lakes. “Planets that appear frozen on the surface could hide liquid water below,” Wandel explained. “These hidden reservoirs could be potential habitats for life, dramatically widening the number of worlds worth investigating.”
The findings also help make sense of recent observations by the James Webb Space Telescope, which detected water vapor and other gases in the atmospheres of warm, close-in Super-Earths orbiting M-dwarf stars—planets previously thought outside the safe range for water.
By challenging the old rules for where life-friendly conditions can exist, Wandel’s study reframes the search for habitable worlds. “The universe may be far more accommodating to life than we’ve imagined,” he said.
Planets once considered too extreme — too hot, too cold, or facing permanent darkness — may now be regarded as promising candidates in the hunt for life beyond the solar system. As astronomers continue exploring distant worlds, the findings suggest the cosmic map of potential habitats could be far larger than previously believed.
The findings could help astronomers focus their search for life by identifying planets that were previously dismissed as too hot, too cold, or permanently dark. By refining models of planetary climates, the study provides a clearer picture of how heat and water might behave on these unusual worlds, improving predictions of which planets could support life. The study may also shed new light on extreme climate dynamics on Earth.
Related Topics
