This is the 5th in a series of caches based on the Solar System. Solar System #5 Mars is the 4th planet from the Sun (Solar System #1), 2.2km from the 1st cache, 227,900,000 km in reality. The remaining 7 (Mercury, Venus, Earth, Jupiter, Saturn, Uranus & Neptune) are placed at increasing intervals from 'The Sun' on theoretical orbits i.e not linear but at increasing distances in differing directions.