Life on Planet EarthSection 2.1

Earth FactsAverage Distance from the Sun: 149,597,890 kmTravels through space at 107,229 km/hThe earth isn't perfectly round, it is slightly

fattened at the north and south poles.Scientists have the dated the Earth as being

between 4 and 5 billion years old!Earth is mostly iron, oxygen and silicon70% of the Earth's surface is covered in waterThe Earth's atmosphere extends out to 10,000

km

The AtmosphereLayers of gases that surround

EarthMade up of 78% nitrogen, 21%

oxygen and <1% argon, water vapour, carbon dioxide and other gases

Acts like a blanket and moderates surface temperatures.

Blocks solar radiation (UV light)Made up of the troposphere,

stratosphere and mesosphere.

The LithosphereEarth’s outer layer, the

rocky shell of EarthThe mountains, ocean

floors and rest of Earth’s solid landscape.

Ranges from 50 to 150 km in thickness

The HydrosphereMade up of all the water on Earth:

Solid - glaciersLiquid – lakes, oceans, etc and groundwaterGas – clouds, water vapour

97% of Earth’s water is contained in the oceans.

The BiosphereThe zone around Earth where life can exist

Most can be found on land and in water Some micro-organisms can live several kms

below the earth’s surfaceCan have artificial biospheres