Earth

Earth
The Earth
Date of Discovery	Antiquity
Atmospheric Makeup	78% nitrogen, 20.5% oxygen 0.9% argon 0.04% carbon dioxide
Distance from Sun	150 million km 93 million miles 1 astronomical unit
Diameter	12,742 kilometers 7926 miles
Volume	1 trillion cubic kilometers
Axial tilt	23.4 degrees
Orbit	365.25 (1 year) Earthen days
Position in Solar System	Third planet from Sun
Surface Features	29.2% land 70.8% water
Albedo	(geometric) 0.367 (bond) 0.306
Aphelion	152 million km 95.06 million miles
Perihelion	147 million km 91.936 million miles
Mass of Planet	5.974 x 10^24 kg
Escape Velocity	11.12 km/s

The Earth is the third planet from the Sun. About 70% of the surface of the Earth is covered in salt water oceans, and the remainder consists of continents and islands. There is significant interaction between the Earth and its space environment. The relatively large Moon provides ocean tides and has gradually modified the length of the planet's rotation period. A cometary bombardment during the early history of the planet is believed to have formed the oceans. Later, asteroid impacts are understood to have caused significant changes to the surface environment. Changes in the orbit of the planet may also be responsible for the ice ages that have covered significant portions of the surface in glacial sheets.

History

Earth history refers to the development of planet Earth and covers about 4.5 billion years—approximately one-third of the age of the universe, of the 13,700 Ma estimated since the Big Bang—from its formation to the present day.

Continents

ordered by size (landmass)

• Asia
• Africa
• North America
• South America
• Antarctica
• Europe
• Australia

Trivia

• The largest ice sheet on Earth is located in Antarctica.
• The Moon is moving away from the Earth.

Gallery

Earth and the Sun

External links

• WikiSatellite view of Earth at WikiMapia
• USGS Geomagnetism Program
• Overview of the Seismic Structure of Earth PDF
• NASA Earth Observatory
• Beautiful Views of Planet Earth Pictures of Earth from space
• Java 3D Earth's Globe
• Projectshum.org's Earth fact file (for younger folk)
• MySolarSystem.com - Earth Facts about Earth and the moon.
• Google Earth
• Earth on Wikipedia
• NASA's Earth fact sheet
• space.about.com - Earth - Pictures and Astronomy Facts