James Webster, a geologist with the American Museum of Natural History in New York, walked us through the science of a term we've been hearing a lot today: lava bombs.
"Lava bombs are actually — it was molten material that was blown out of a fissure, or a small cone in the ground. And it's cooling as it moved through the air, but it's still very high temperatures."
The bombs are propelled through the air by "expanding gases," he said.