Psychology Glossary. Genotype. The total set of genes contained within an organisms cells. Organisms contain some genes that are expressed (you can consider the expressed to mean that the gene is active or being used) and some that are not. Regardless, all the genes an organism has are considered the genotype.
Mars' closest approach to the Earth is called opposition, and occurs roughly every 780 days.
Since Earth and Mars both orbit the Sun but at different distances and different speeds, the distance varies. So Earth and Mars can be as close as about 55 million kilometers, or as far as about 400 million kilometers - quite a difference. On average, they're about 225 kilometers apart.