Black holes are a fixture of science fiction -- whether it's the time-warping regions of space seen in the 2014 movie Interstellar to the all-consuming planet destroyers of Star Trek. But while Hollywood gives us a version of these parts of the universe for the big screen (with plenty of artistic license), what's the truth behind the fiction? 

The answer is both seemingly simple and staggeringly perplexing.

"A black hole is just a region of space where gravity is so strong that light can't escape," said Regina Caputo, a research astrophysicist at the NASA Goddard Space Flight Center. "That poses a lot of challenges for astronomers because if light can't escape, then we can't see them."

That gravity is the result of a huge amount of mass in a small area that  draws in everything in its path, from dust and gas to stars and even other black holes. For smaller black holes, that mass is generated when a star burns up all its fuel and collapses in on itself -- what Caputo called a "catastrophic death." But in the case of supermassive black holes, which can be equivalent to the mass of billions of stars, scientists still have unanswered questions. 

"These are black holes that are at the centers of galaxies [and] we don't actually know how they get that big," Caputo said. "We think it might be the merging of other black holes, so galaxies merging together to make these really super billion solar mass objects."

While scientists have captured the first images of black holes, and even managed to remix the pressure waves from a black hole into a kind of interstellar soundtrack, there's plenty that still remains unknown about these mysterious voids. 

Check out the video above to see our deep dive on black holes with Caputo of the NASA Goddard Space Flight Center, covering everything from how black holes are formed to what lies in their centers and what they can teach us about the universe.