How did we get water on earth?
Our water is actually meteoroids that hit Earth a long time ago.
http://www.smithsonianmag.com/science-nature/how-did-water-come-to-earth-72037248/?no-ist
The presence of water on Earth is believed to have originated through a process called accretion, which took place over billions of years during the early formation of the solar system. Here's an explanation of how scientists theorize water came to be on our planet:
1. Nebular Hypothesis: According to the prevailing scientific theory of planet formation, known as the Nebular Hypothesis, the solar system began as a vast cloud of gas and dust called a nebula. Gravity caused this nebula to collapse, forming a rotating disk of material.
2. Formation of the Sun: In the center of this rotating disk, the Sun began to form through a process known as nuclear fusion. The intense heat from the early Sun prevented volatile materials, like water, from condensing and remaining close to it.
3. Formation of the Terrestrial Planets: Within the disk, smaller clumps of material called planetesimals began to form. These planetesimals collided and merged over time, eventually building up the terrestrial planets, including Earth.
4. Late Heavy Bombardment: Around 4.6 billion years ago, during a phase known as the Late Heavy Bombardment, numerous asteroids and comets bombarded the inner solar system. Some of these objects carried water in the form of ice.
5. Delivery of Water by Asteroids and Comets: It is believed that volatile-rich asteroids and comets from the outer regions of the solar system delivered water by colliding with the early Earth. These impacts likely occurred after the Earth had formed and its surface had cooled.
6. Water Outgassing: Additionally, water may have been brought to the surface through volcanic activity. Volcanoes release gases, including water vapor, from deep within the planet. Over time, this water vapor condensed and formed oceans and other bodies of water on Earth's surface.
It's important to note that the exact processes and timing of how water arrived on Earth are still areas of active scientific research. However, the currently accepted theories suggest a combination of both delivery by asteroids and comets, as well as outgassing from volcanic activity.