The Surprising Habitability of Ignan Earths

Could a rocky planet have so much internal heating that it becomes uninhabitable? Surprisingly, the answer seems to teeter on the edge of potential. Consider Io, one of Jupiter's moons—this volcanic world boasts a staggering heat flux of around 2 watts per square meter, a dizzying contrast to Earth's much cooler 90 milliwatts.

Tidal Venus Limit

What's particularly intriguing is the concept known as the Tidal Venus Limit. This is the hypothetical point at which a planet's internal heating surpasses the Runaway Greenhouse Limit of 300 watts for an Earth-sized world. Between the extreme examples of Io and a potential Tidal Venus scenario lies a vast range of internal heating rates whose implications for habitability remain largely uncharted territory.

Exploring Ignan Earths

In our new research, we delve into the intriguing domain of what we are calling Ignan Earths—terrestrial planets that might sustain conditions conducive to life despite the extremes of internal heating. Findings suggest that even with elevated internal temperatures, the planet's mantle could remain solid, creating the conditions necessary for a stable and buoyant crust.

Modeling Climate Dynamics

To gain deeper insights, we modeled the long-term climate dynamics of Ignan Earths by emulating the carbonate-silicate cycle, particularly under a heat-pipe tectonic regime, a process predicted to be prevalent on these unique worlds. As we explored various levels of internal heating, we uncovered some fascinating results: Earth-mass planets with heat fluxes below 15 watts might maintain average surface temperatures similar to those experienced in Earth’s most temperate epochs (below 30°C). Remarkably, even planets with significantly higher internal heating rates could sustain surface temperatures well below a critical threshold of 100°C.

Implications for Astrobiology

This research opens the door to a broader understanding of planetary habitability by showcasing how life may adapt even in environments once deemed too hostile. Ignan Earths present a new frontier in astrobiology, suggesting that life could thrive in far more diverse conditions than previously imagined. As we continue to explore these extreme conditions, we may find that the universe is more teeming with potential life than we dared to dream!