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The Third Planet

Earth is the third planet from the Sun in the solar system and the only planet or object in the universe known to harbor life. Astronomers have estimated that the Earth formed about 4.54 billion years ago, or about 60 million years after the Sun.

Earth Quick Facts

Type of Planet Terrestrial
Moons The Moon
Rings None
Mass 5.972 × 1024 kg
Volume 1,083,000,000,000 km3
Closest Distance to Sun 147,100,000 km
Furthest Distance from Sun 152,100,000 km
Average Orbital Speed 107,200 kph

Did you know?

  • Earth's continents have been combined into a single supercontinent in at least one point in its history.

    It's not a coincidence that the continents almost seem to fit together like the pieces of a jigsaw puzzle. Pangea, a supercontinent where all of today's Earth's continents were combined into one, was formed about 335 million years ago and began to separate about 175 million years ago. It was centered near Earth's equator and surrounded by the superocean named Panthalassa, which occupied about 70% of Earth's surface.

  • The elements iron, oxygen, silicon, and magnesium make up about 91.2% of Earth.

    By mass, Earth is made out of approximately 32.1% iron (Fe), 30.1% oxygen (O), 15.1% silicon (Si), and 13.9% magnesium (Mg). Sulfur (S), nickel (Ni), calcium (Ca), and aluminum (Al) are slightly less common, followed by every other element on the Periodic Table combined making up only 1.2% of the Earth by mass.

  • A year on Earth is actually longer than 365 days.

    It really takes about 365.2422 (almost 365 and a quarter) days for the Earth to complete a full orbit around the Sun. Wait a minute—doesn't that mean that, every four years or so, we'll have an entire extra day? Yes! Every four years, we add an extra day to the calendar, February 29th, and the year becomes a leap year.

  • Though we usually think of it as a globe, the Earth isn't actually a perfectly round sphere, or ball.

    The Earth's true shape is what's known as an oblate spheroid, a kind of flattened sphere, or ball. Because of the force caused by Earth's rotation, the equator bulges slightly outward. In fact, if you were to travel around the equator, you'd be traveling about 43 km more than if you were to travel around the Earth from pole to pole.

    This leads to the strange fact that, although Mount Everest is the tallest mountain on Earth, the point furthest away from Earth's center is actually Mount Chimborazo in Ecuador. Additionally, because the force of gravity is affected by your distance from the center of the Earth, you would weigh slightly less on the equator than at one of Earth's poles!

  • About 71% of the Earth's surface is covered by water.

    Though we don't think of it much, land only covers less than a third of Earth's surface. This is why Earth has the nickname the "Blue Planet." About 96.5% of this water is held by Earth's oceans.