Space is expansive: looking up to the stars, it can sometimes feel like everything sits on a single, two-dimensional sheet held up above us. It doesn't, of course—so how do we measure how far away things are?
In this video, Yuan-Sen Ting explains how everything from trigonometric parallaxes to, um, standard candles can help us size up space. Above all, it really puts into perspective exactly what we can do from humble little planet. [TED Ed]