Space
The Moon Landing
The computer that guided Apollo 11 safely onto the Moon had a small fraction of the processing power of a basic modern calculator.
Black Holes
An object so extreme that its very first direct photograph wasn't taken by a single telescope, but by linking radio dishes across the entire planet into one Earth-sized instrument.
Exoplanets
A category of planet that scientists can't actually see directly in most cases — instead, they detect them by watching for a star's light flickering, ever so slightly, as something passes in front of it.
Mars Exploration
A planet that once likely had rivers and lakes, and that a fleet of robotic rovers has spent decades methodically trying to prove it.
The Big Bang
Not actually an explosion in space — it was the expansion of space itself, everywhere at once, starting roughly 13.8 billion years ago.