The amount of radioactive elements in a planet’s core may be a key factor in determining its habitability. In this image, too much radiogenic heating stifles convection and the generation of a magnetic field while triggering mass extinction-level volcanism. All images: University of California-Santa Cruz/Melissa Weiss
As it turns out, organic material, liquid water, sunlight and, possibly, a large moon might not be enough to ensure an exoplanet’s habitability. It also may depend in part on whether enough long-lived radioactive elements are present in the planet’s deep interior.
That’s because the radioactive decay of uranium and thorium produce the heat needed to power plate tectonics and volcanism, driving convection in a planet’s molten metallic core. That convection, in turn, creates an internal dynamo in Earth’s interior that produces a protective magnetic field, shielding the surface from the harmful effects of solar radiation.
A planet like Earth, depicted here, has just the right amounts of thorium and uranium in its core to generate dynamo-creating convection and a magnetic field that shields the surface from the harmful effects of solar radiation.
In a paper published 10 November in Astrophysical Journal Letters, researchers at the University of California-Santa Cruz considered how different amounts ...