Lava isn't like water, snow or mud. It's liquid rock, so it's heavy, sticky and moving underground. It's also nearly 2,000 degrees.

One way to find water worlds beyond our solar system could be to look for minerals — or more specifically, to study minerals mixed with cool lava on exoplanet surfaces.

The latest eruption broke out around 6 a.m. local time Thursday northeast of Mount Sýlingarfell, spewing lava fountains roughly 260 feet in the air and giving rise to a nearly 2-mile volcanic plume.