Earth

Earth is the third planet in the Solar System.

Origin of Name
People called the dirt that they walked on "earth", and they decided to name a planet after that earth.

Earth in Relation to the Solar System
Earth is the third planet from the Sun. It has one moon. It is about 93 million miles away from the Sun. It has a revolution period of 365 Earth days (one Earth year).

It has a rotational period of 23 hours, 56 minutes, and 59 seconds (1 Earth day). This extra 3 minutes and 1 second add up over time, and that's why we have leap years.

Structure of Earth
Earth has an atmosphere, a crust (about 20 miles thick), a mantle (1802 miles thick), a liquid outer core (about 1400 miles thick, made of iron), and a solid inner core. Convection occurs in the mantle.

Other Characteristics of Earth
Earth has a diameter of 7,917.5 miles. Earth has an atmosphere of 78% nitrogen, 21% oxygen, 2% argon, and 1% other elements, such as carbon, helium, and xenon.

Life on Earth
Earth has life on it. Millions of diverse species live on the planet, but most of them are invertebrates. Humans may be the most influential life form on the planet, contributing to the extinction of many species and deforestation.

Earth also has liquid water.

Earth in Pop Culture
Earth has been the victim of many alien invasions, as well as many humans trying to conquer the world. Some superhero usually saves Earth in the nick of time.

In the game Twilight Imperium, Fourth Edition, Earth is renamed "Jord" (Swedish for "Earth").