While no one knows for certain how the Earth formed, scientists theorize that it formed over 4 million years ago after the sun went through its initial formation, gravity began to draw heavy particles together into a planet and solar winds blew away lighter gases. These heavy particles became the core of the planet. As the mass continued to grow, heavier particles sank to the center, according to Space.com.
As the Earth was forming, an object from space struck the new planet, causing particles to fly into space. Gravity pulled the particles together to form the moon. The remains of the object joined with the Earth to increase its overall size. Subduction in the Earth's mantle caused the formation of tectonic plates. These same forces caused the plates to divide and form the continents.
Earth's first atmosphere was blown away by solar winds. A second atmosphere formed from outgassing of the elements that formed the core. This second atmosphere included water vapor, nitrogen, carbon dioxide and other gases. The cooling cycle resulted in the formation of rain, leading to the development of oceans. This atmosphere was also instrumental in the development of life on the planet, according to Wikipedia. As life developed, the atmosphere changed again, due to the release of oxygen through photosynthesis.Learn More
The Earth is referred to as "the blue planet" because of the abundance of water on the planet. Over 70 percent of the Earth's surface is comprised of water, producing a vivid blue color when viewed from space.Full Answer >
According to astrobiologist Jack O'Malley-James of the University of St. Andrews in Scotland, the sun will grow large enough to extinguish all life on Earth in roughly 2.8 billion years. The planet's non-microbial life will become extinct in 800 million to 1.3 billion years.Full Answer >
Astronomers theorize that over 4.5 billion years ago, Theia, an object about the size of Mars, collided with Earth to create a tilted axis. This is called "the giant impact theory." Prior to this event, the axis was straight at 180 degrees.Full Answer >
It takes the Earth approximately 365.25 days to complete one revolution around the sun. The extra quarter of a day that is gained each year is why a leap year is added to the calendar every four years. The day added in a leap year is February 29.Full Answer >