The letters outside of the punnet square stand for the Genotypes coming from either parent. The letters inside the square stand for the genotypes the child is likely to get.
Mars is about half the size of Earth by diameter and has a much thinner atmosphere, with an atmospheric volume less than 1% of Earth's. The atmosphere of Mars is about 100 times thinner than Earth's, and it is 95 percent carbon dioxide.
The atmospheric composition is also significantly different: primarily carbon dioxide-based, while Earth's is rich in nitrogen and oxygen.
Because of the differences in atmospheric densities and distances from the sun, the temperature within the atmosphere are also wildly different. Earth generally ranges from 14 degrees Celsius to 70.0 degrees, whereas Mars ranges from -146 degrees C to -140 degrees C.
Both planets have a silicate mantle surrounding their cores and a surface crust of solid material.
Earth and Mars’ both have terrains that varies considerably from place to place.
