Interactive scale model
If Earth were 1 mm wide…
The ratios stay the same at every model size. Change one number and the whole Earth–Moon–Sun model updates.
Moon diameter
0.273 mm27.27% of Earth’s diameterEarth–Moon distance
3.017 cmaverage center-to-center distance · 30.17 Earth diametersSun diameter
10.92 cm109.2× Earth’s diameterEarth–Sun reference distance
11.741 m1 au · 11,741 Earth diametersActually to scale
Earth and Moon size + distance
This strip uses one screen unit per Earth radius, so the Earth–Moon spacing and their relative diameters are drawn to the same linear scale. The Sun cannot fit on this strip: at the same scale its center would be about 389× farther away than the Moon.
If your Earth is 1 mm wide, put a 0.273 mm Moon about 3.017 cm away. The Sun would be 10.92 cm wide and roughly 11.741 m away.
Reference values
Where the ratios come from
FactToon uses NASA’s volumetric mean radii: Earth 6,371.0 km, Moon 1,737.4 km, and Sun 695,700 km. The average Earth–Moon distance is 384,400 km. One astronomical unit is defined as exactly 149,597,870.7 km.
Distances here are center-to-center reference distances. The Earth–Moon distance varies through the Moon’s orbit, and Earth’s actual distance from the Sun varies through the year.