Logarithmic, not linear
On a true linear scale, Mercury through Mars would bunch up in the first few pixels and Neptune would be off-screen. The distance view above uses a log scale to keep every planet visible.
No single diagram can show planet size and orbital distance accurately at the same time. Switch between the two views below to see why — the same eight planets, drawn two honest but incompatible ways.
Diameters are accurate here. Spacing between planets is arbitrary — just enough room to fit each ball. Jupiter really is about 11× Earth's diameter.
Distances from the Sun are accurate here (on a compressed logarithmic scale, left to right). Every planet is drawn as the same small dot — at true relative size, the inner planets would be invisible pixels.
On a true linear scale, Mercury through Mars would bunch up in the first few pixels and Neptune would be off-screen. The distance view above uses a log scale to keep every planet visible.
Real orbits are ellipses, and this simplification (like most diagrams) treats distance as a single number rather than a range.
Planets don't orbit in exactly the same plane. This diagram, like almost every solar system diagram, flattens that out.
Distinguishing photos from models.
See the same size/distance trade-off explained on the homepage's Scale Lab.
Build a physical model and feel the size/distance trade-off in a hallway.