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Black holes may be among the strangest – and most commonly misunderstood – objects in our universe. The remnants of the most massive stars, they sit at the limit of our understanding of physics. They can contain several times the mass of our sun in a space no larger than a city. With gravity so intense that not even light can escape their surfaces, black holes can teach us about the absolute extremes in the cosmos and the very structure of space itself.

The black hole itself is defined by a volume of space delineated by an “event horizon”. The event horizon invisibly marks off the boundary where the escape velocity is exactly equal to the speed of light. Outside of the horizon, your spaceship has at least a theoretical chance of making it home. Crossing that line sets you on a one-way journey to whatever sits inside.

The bottom line is that black holes are the burying grounds of extremely massive stars. Following a supernova explosion, the massive core is left behind. Lacking a suitable balancing force, gravity pulls the core together to a point where the escape velocity exceeds the speed of light. From this point on, no light – and no information of any kind – can radiate into space. All that remains is a perfectly black void where once a mighty star stood.