Picture a line with $1 million on the left and $1 trillion on the right. Where would you place $1 billion? Now try it: $1 billion is all the way on the left, crunched up against $1 million—and nowhere ...

Elon Musk became the world’s first trillionaire Friday when SpaceX went public. But what does 1 trillion actually mean? Here’s how to think about its immensity and the power it represents. SpaceX’s ...