Sagging

drag the sun. the floor does the pulling.

drag a sun across a stretched rubber sheet and steer an orbiting earth by moving the floor under it

The earth here feels no pull at all. Its only rule is to roll downhill on the sheet, and the sun is what bends the sheet. Einstein's picture of gravity is like this: mass curves spacetime and things follow the curve. A rubber sheet is only a sketch of it, since real spacetime curves in time as well as space.

Concepts: gravity, relativity, orbits, elasticity, geometry.

An interactive you play with one thumb, on Wundr.