The Solar System — Analyse

When comparing planetary data on orbital distance, orbital period, density, surface temperature and surface gravitational field strength, what patterns would you expect to see and why?

Orbital distance and orbital period: the greater a planet's average distance from the Sun, the longer its orbital period, since it must travel a much larger circumference and the Sun's gravitational pull (and so orbital speed) is weaker at greater distances. Density: the four inner rocky planets (Mercury, Venus, Earth, Mars) have high densities (thousands of kg/m^3) as they are made of rock and metal, whereas the four outer gas/ice giants (Jupiter, Saturn, Uranus, Neptune) have much lower densities, being made mostly of hydrogen and helium. Surface temperature: this generally decreases with increasing distance from the Sun, since more distant planets receive less solar radiation per unit area (Venus is an exception, being hotter than Mercury because its thick atmosphere traps heat). Gravitational field strength at the surface: this depends on both a planet's mass and its radius, not on size alone - a large, low-density planet can have a lower surface gravity than a smaller, denser one.