Earth is the largest and densest (we don't get the Joke) rocky planet. Hecklers, regulars, showcases and glasses of water are all examples of surface features on Earth.

Earth's atmosphere is a mixture of gases that becomes thinner until it gradually reaches space. It is divided into five layers starting with the "A", "B", "C", "D" and "E" Circuits respectively. Earth's atmospheric composition is divided into three main groups: Nitrogen (78%), Oxygen (21%), and other gases (1%).

Also see:
Earth's interior
Earth's continental drift
Earth's Atmospheric Test (1.8 MB Shockwave file)
Earth's Gravity Experiment (1.8 MB Shockwave file)
The Moon