Is earth smooth

Earth is relatively smooth compared to many other small planets and planetoids.

It is not smooth from a purely human perspective. For anyone who has hiked to the peaks in Glacier Park, and then realized that there are mountains three times as high, the world does not appear smooth.

The roughness on the earth's surface (mountains and valleys) amounts to about 1/1000 of the earth's radius, which makes it pretty smooth as planets go.