|Mass||5.97 x 1024 kg|
|Volume||1.08 x 1021 m3|
|Mean Density||5.52 g/cm3|
|Mean Distance from Sun||150 x 106km = 1 AU|
|Eccentricity of Orbit||0.017|
|Inclination of Equator to Orbit||23.5°|
|Inclination of Orbit to Ecliptic||0°|
|Colour||Blue and Green|
ranges from -50°C to +40°C
Small amounts of carbon dioxide, hydrogen and others
Some water vapour
|Length of Day||23.9 hours|
|Length of Year||365.25 days|
|No. of Moons||1|
|Surface Pressure||1 atmosphere (1 bar)|
|Escape Velocity||11 km/s|
Earth is the third planet in our Solar System and is the only planet in the Universe known to support life. 71% of its surface is covered by water.
The greenhouse effect raises the average temperature of the Earth from –21 C to +14 C. Without the greenhouse effect, our oceans would be frozen and life could not exist. The greenhouse effect is now threatening our planet because it is out of control due to the high levels of carbon dioxide and water vapour in our atmosphere. These are transparent to incoming ultraviolet radiation from the Sun. As the radiation strikes the surface it is absorbed and re-radiated in the infrared. CO2 and water are both opaque at these wavelengths, and so the radiation cannot escape. The atmosphere therefore warms up.
The Earth is protected from harmful solar radiation by the ozone layer. This radiation would otherwise kill all life on the planet. Our ozone layer is currently being destroyed by chemicals released by human activity, creating holes over the North and South poles.
Authors: Carolyn Brinkworth and Claire Thomas
Last updated: July 2001