When we pass by something every day, it's easy to get used to picturing it a certain way. Bit by bit, that mental image becomes more ingrained into our brains and, as that happens, we stop thinking about the little details that may be influencing our perception.
And if our assumptions are mundane enough, we don't usually run into any reason to challenge them. A young child with a million questions might land on one that makes us realize we don't really know as much as we think, but that's a matter of sheer luck and circumstance.
But today, what we think we know about the size of certain things in our lives will be turned on its head. Because it turns out that a lot of things in this world are bigger than we think they are.