Our Solar System Consists of: Sun Eight planets and their moons The dwarf planets The planets are all unique and differ in terms of their: Size (volume) Surface temperature Chemical elements (e.g. H2, He, O2 and C) Gravitational field strength (surface gravity)

The planets orbit the sun in the following order: M V E M J S U N P “My very elderly mother just sent us nine pizzas”

The Inner (Terrestrial) Planets The four planets closest to the sun are: Mercury, Venus, Earth and Mars Characteristically they are: Small High in density Mainly composed of rocks/metals

The Inner (Terrestrial) Planets Venus Mercury Earth Mars

The Outer Planets (Gas Giants) The four planets farthest from the sun are: Jupiter, Saturn, Uranus & Neptune Characteristically they are: Large Low in density Mainly composed of gases such as hydrogen and helium Separated from the inner planets by the asteroid belt.

The Outer (Gas Giant) Planets Jupiter Saturn Uranus Neptune

Dwarf Planets The big difference between a dwarf planet and a regular planet is that: A dwarf planet’s path around the sun is full of other objects like asteroids and comets whereas a regular planet has a clear path Pluto Due to its strange orbit and tiny size astronomers questioned whether it should be considered a planet. A decision was made to reclassify Pluto to a dwarf planet in 2006.

Ceres, Eris, MakeMake & Haumea The Dwarf Planets Ceres, Eris, MakeMake & Haumea Ceres (formally an asteroid and still found in the asteroid belt), Eris, MakeMake & Haumea are also dwarf planets. They are different from planets because they are not big enough to clear their orbits and thus orbit with a lot of other debris. Eris Ceres Pluto