Mars and Earth Size Comparison

The true scale difference between Mars and Earth.
Earth and Mars rendered at their true relative diameters.

What the simulation shows

This scene places Mars next to Earth using their real physical diameters and full 3D geometry, each wrapped with detailed planetary textures. Earth rotates with its characteristic ocean–continent distribution, while Mars turns as a dry, cratered desert world. Maps and textbooks often show the two planets at similar sizes, but their true scale difference is much larger. Mars is not “almost like Earth,” but rather a smaller, colder world with far less surface area to work with. Seeing them side by side gives an immediate sense of proportion that diagrams struggle to convey.

The numbers behind the scale

Earth’s diameter is approximately 12,742 km. Mars has a diameter of about 6,779 km. The diameter ratio between them is:

DEDM=12,7426,779≈1.88\frac{D_E}{D_M} = \frac{12{,}742}{6{,}779} \approx 1.88

Volume scales with the cube of the diameter. When we apply that:

(1.88)3≈6.6(1.88)^3 \approx 6.6

This means Earth could contain more than six Mars-sized volumes. Surface area, which is what we physically see, scales with the square of the diameter:

(1.88)2≈3.5(1.88)^2 \approx 3.5

So Earth’s visible disk is about three and a half times larger than Mars’s. These exact proportions are preserved in the simulation, allowing you to feel the scale difference intuitively while rotating the worlds freely in 3D space.