earth

earth

[urth]

Earth is a planet located in the Milky Way Galaxy and is the planet on which we live. Earth is home to a diversity of animal and planet life and is the third-closest planet to the sun.

Earth was formed approximately 4.5 billion years ago and life began to appear within one billion years of its creation. Earth is the only planet we are aware of that harbors life. Earth is unique due to its abundance of water and life and without liquid water, life can not exist.

Earth is known as a rocky body, making it a terrestrial planet. It is the largest of four terrestrial planets in our solar system; the other three are Mercury, Venus, and Mars. The earth is composed of a variety of different elements. The inside of the Earth is called the core which is composed primarily of nickel and iron. The Earth's mantle surrounds the core and it is composed primarily of different types of rock including aluminum, silicon, iron and magnesium. The top layer of earth is called the crust and is composed primarily of oxygen, aluminum, iron, calcium, sodium, potassium and magnesium. Approximately 70 percent of the Earth's crust is covered in water while the rest is land.

The Earth orbits the sun in an elliptical rotation once every 365 days and spins on its axis at a rate of over 1,000 miles per hour, making a full rotation once every 24 hours. The Earth is constantly being pulled towards the Sun due to the Sun's gravity but the Earth spins in the opposite direction, keeping it in a steady orbit. Without the Sun, the Earth would not exist.

The Earth is home to land, water, air and life. It is constantly changing. Each ecosystem on Earth is related and interconnected. Without all of these systems working in conjunction the Earth would cease to exist.

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