No star, no problem: Radioactivity could make otherwise frozen planets habitable0

• From Around the Web, Space
• April 8, 2020

Not too close, but not too far. That’s long been the rule describing how distant a planet should be from its star in order to sustain life. But a new study challenges that adage: A planet can maintain water and other liquids on its surface if it’s heated, not by starlight, but by radioactive decay, researchers calculate. That opens up the possibility for many planets—even free-floating worlds untethered to stars—to host life, they speculate.