The name Earth is at least 1,000 years old. All of the planets, except for Earth, were named after Greek and Roman gods and goddesses. However, the name Earth is a Germanic word, which simply means “the ground.”
Size and Distance
With a radius of 3,959 miles (6,371 km), Earth is the biggest of the terrestrial planets, and the fifth largest planet overall.
From an average distance of 93 million miles (150 million km)Earth is away from Sun, Earth is exactly one astronomical unit away from the Sun because one astronomical unit (abbreviated as AU).
It takes about eight minutes for light from the Sun to reach our planet.
Here's how our Earth Looks.
A 3D model of Earth, our home planet. Credit: NASA Visualization Technology Applications and Development (VTAD)›
Formation
When the solar system settled into its current layout about 4.5 billion years ago, Earth formed when gravity pulled swirling gas and dust in to become the third planet from the Sun. Like its fellow terrestrial planets, Earth has a central core, a rocky mantle and a solid crust.
Why did life exist here?
Earth has a very hospitable temperature and mix of chemicals that have made life possible here. Most notably, Earth is unique in that most of our planet is covered in water, since the temperature allows liquid water to exist for extended periods of time. Earth's vast oceans provided a convenient place for life to begin about 3.8 billion years ago.
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