EARTH

=__**The Earth**__=

== The planet Earth is the planet we live on. It is the third planet from the Sun in our Solar system. It is the only planet in our solar system which contains life. It contains millions of species and 1000's of extinct ones. The Earth formed approximately 4.54 billion years ago. But only life appeared on it around a billion years ago. During that period of time, the Earths biosphere altered to its atmosphere and to the heat and cold. The ozone layer is located in the atmosphere. It protects us from the harmful radiation of the sun. Approximately 71% of the Earth is covered by salt-water. The rest of the surface are islands and continents. ==

[[image:240px-The_Earth_seen_from_Apollo_17.jpg width="177" height="177" caption="The Earth"]]
== Underground in the Earth it consist of special layers. The layers from the top to the bottom are; the crust, the upper mantle, mantle, outer core and inner core. == == The atmosphere on the Earth consists of five main layers. They are the Exosphere, Themosphere, Mesosphere, Stratosphere and the Troposphere. ==

media type="youtube" key="ObzQOztMaZ4&hl=en" height="344" width="425" Planet Earth