if the earth is 1cm in diameter
to determine the diameter of the other planets is the ratio of the earth to the planets
Planet diameter ( from google)
Mercury 4,880 km
Venus 12,100 km
Earth 12,800 km
Mars 6,800 km
let X = plants diameter and use mercury as an example
Earths diameter= 12800
X= 4880km/12800km 0.381 cm
143,000 km
120,000 km
52,000 km
48,000 km