Where does the water on earth come from?
We often compare the earth to a blue water ball, because 71%of the entire earth surface is covered by the ocean, and the average depth of the ocean is about 3,700 meters, so the total amount of water in the ocean is sufficient It is 1.3 billion cubic kilometers, so from outer space, the earth looks like a blue water ball, but where does so much water come from?
For this question, there are currently two ways of saying it, namely :Self-carrying theory, externally speaking
Let’s first look at the self-carrying theory. Simply put, we think that the earth’s water comes from the earth itself. In this regard, let’s first understand the formation process of the earth.
The formation of the earth and the formation of the solar system are basically synchronized. When the nebula in the universe begins to shrink, most of the mass begins to gather towards the center, and the surrounding area is filled with interstellar dust, most of which is ice , Rock quality is the main thing. Although the mass of these small dusts is not large, the quantity is dominant. Therefore, under the action of gravity, they gradually accrete together and become larger in size, and then continue to collide and merge with each other, and finally form the earth (although From a human perspective, the planets are already very huge, but we must know that 99.86%of the mass of the entire solar system is concentrated in the sun).
So in this way, the earth itself It carries water, and then in the long and frequent geological activities, the water distributed in the earth is released. For example, volcanic eruption forms water vapor, and finally it becomes liquid and stored on the surface as the earth cools .
However, many scientists believe that the earth’s own water is not enough To form today’s ocean, they believe that the water on the earth should mainly come from outer space, that is, small celestial bodies in the solar system such as comets, which were brought when they hit the earth (some scientists also believe that the earliest life on the earth was also brought in this way. Here).
You can imagine, Considering the chaotic era of the early solar system, the collisions between celestial bodies are very frequent, because it makes sense that the water on the earth comes from outer space. In general, the water on the earth should be a mixture of itself and foreign. .