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.
|Type of Planet||Terrestrial|
|Mass||5.972 × 1024 kg|
|Closest Distance to Sun||147,100,000 km|
|Furthest Distance from Sun||152,100,000 km|
|Average Orbital Speed||107,200 kph|
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.
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.
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.
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!
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.