I saw a show on TV a while back where some town modelled the solar system in their town. They had the Sun represented by a large sphere placed in the center of the town. Mercury was located x blocks away and was the size of a golf ball, Venus a bit further out and a bit bigger, etc. Pluto was several miles outside of town and quite small, if I remember correctly.
So, taking that concept a step further, if the Universe were scaled down to be the size of the Earth, how big would the Earth be? As big as a grain of sand? Smaller than that? And, while we’re at it, how far would our space exploration to date extend in this scale?