The idea of a moon having its own moon sounds strange but fascinating. People often wonder if a smaller object could orbit around a regular moon, just like moons orbit planets. Scientists have ...

Free-floating, planetary-mass objects that are just drifting carefree through the galaxy, untethered and starless, appear to be able to generate their own systems of moons, like a planetary system on ...

So far, humanity has yet to find its first "exomoon"—a moon orbiting a planet outside of the solar system. But that hasn't ...

Could the icy moons of our solar system hold life beyond our planet? Keith Cooper looks at how planetary scientists plan to find out ...