Earth: The Blue Planet
Earth is the third planet from the Sun in our solar system, often called the "Blue Planet" due to its
vast oceans and life-sustaining atmosphere. It is unique in the solar system, and possibly the entire
universe, for its combination of physical characteristics and conditions that support a vast diversity of
life. From its physical features and history to its ecosystems and human impact, Earth is a dynamic,
interconnected system that has fascinated scientists and philosophers alike for millennia.
Physical Characteristics
Earth is the fifth-largest planet in the solar system, with a diameter of approximately 12,742
kilometers (7,918 miles). It is composed of several layers:
• The Crust: The outermost layer, a thin, solid shell of rock. It is divided into tectonic plates
that float on the semi-fluid mantle beneath.
• The Mantle: Located beneath the crust, the mantle is made up of semi-solid rock that moves
slowly due to heat from the core. It’s responsible for volcanic activity and earthquakes.
• The Outer Core: This liquid layer is made of iron and nickel and lies beneath the mantle. The
motion of the outer core generates Earth’s magnetic field.
• The Inner Core: The innermost, solid core of Earth, composed primarily of iron and nickel,
with temperatures as high as 5,700°C (10,300°F).
Earth's atmosphere is a thin layer of gases that surrounds the planet, primarily composed of nitrogen
(78%), oxygen (21%), and trace amounts of argon, carbon dioxide, and other gases. This atmosphere
is crucial for life, providing the air we breathe, shielding the planet from harmful solar radiation, and
regulating the climate.
Earth’s Orbital Characteristics
