Earth (Planet)

The Earth.
Credit: Image courtesy NASA Johnson Space Center

Overview

At about 93 million miles from the Sun lies the orbit of our planet Earth. Earth is the largest of the terrestrial planets and the only planet known to support life.

Atmosphere

The Earth has an atmosphere which consists of 78% nitrogen, 21% oxygen and 1% argon and other gases [1] and water oceans which cover 71% of the Earth's surface [2].

The Moon

Earth has one natural satellite, The Moon (or Luna).

Trojan Asteroids

Asteroid 2010 TK₇

2010 TK₇ is a Trojan companion of Earth, librating around the leading Lagrange triangular point, L₄^[1]. Its orbit will be stable for at least 10000 years.

Artificial Satellites

Although the Moon is Earth's only natural satellite our planet has thousands of artificial satellites and on a clear night many of these can be seen just by looking up into the night sky. An artificial satellite may look like a faint dot moving between the stars or may appear as bright as the planet Venus in the case of the International Space Station.

Observation of Earth's shadow during a lunar eclipse

Earth, The Blue Planet, is our home but observation of the Earth as a whole can of course only be acheived by leaving it's surface. There is one way however we can observe the Earth's disc and that is by viewing a lunar eclipse. This is because we are seeing the Earth's shadow pass over the surface of the Moon.