Looking at the moment when the earth is rising from the desolate surface of the moon, the contrast is astonishing! Compared to the dead silence of the moon, the earth is alive! This vitality comes from the ocean, which makes the earth so unique in the solar system!
Where does the earth's water come from? This is an ancient mystery, and the mystery has not yet been fully solved. Once upon a time, scientists believed that the earliest water on earth came from large amounts of water vapor released by volcanic eruptions within the earth. Later research found that Earth's water may have come from the sky, that is, brought into the ancient atmosphere by comets and asteroids carrying large amounts of ice. It is currently widely believed that Earth's water is likely a combination of the two sources.
So how was the ocean born? This also starts with the origin of the earth. About 4.6 billion years ago, some dust, comets, asteroids, and gas in the solar system combined with each other under the influence of gravity and grew larger and larger, forming the earliest Earth. The original earth was just a simple aggregate of rock and ice. As the earth's own gravity continued to increase, the earth began to shrink sharply. At the same time, the radioactive elements inside the rock continued to decay, releasing a large amount of heat energy. Strong gravity attracts more meteorites and asteroids to collide into the earth like moths to a flame, and generates unimaginable heat energy. This heat melts elements such as iron and nickel and leaves the earth in a molten state. As a result, the earth began a major reorganization, with heavy matter sinking to form the core, and light matter rising to form the mantle and crust.
The birth of the primeval ocean
During this period, the earth was extremely turbulent, with frequent earthquakes and volcanic eruptions. The volcano not only erupts magma, but also erupts a large amount of ice that had been swallowed into its "belly" in the form of water vapor. Because the surface temperature is higher than the boiling point, this water exists in the form of steam in the original atmosphere. At the same time, comets and asteroids intrude into the earth intensively, and the large amount of ice they carry is also instantly transformed into steam and stored in the atmosphere, causing the sky to remain dark for hundreds of millions of years. Later, the impact event slowly stopped, the earth's internal temperature gradually decreased, and the earth's crust finally cooled down, so the ready water vapor condensed into rainwater. About 4 billion years ago, there was a downpour on the earth that lasted for 10 million years. This downpour not only completely cooled the earth's surface, but also created a primitive ocean.
Because there is no oxygen in the original atmosphere and the content of acidic gases such as carbon dioxide, hydrogen sulfide, and sulfur dioxide is high, the original ocean is oxygen-deficient, acidic, and low in salt. After hundreds of millions of years of geochemical cycles, such as evaporation, dissolution of rainwater, erosion of rivers, etc., the salinity and chemical composition of seawater finally balanced and stabilized.
Plate theory believes that about 3.8 billion years ago, the earliest cyanobacteria single-celled life appeared in the ocean. As algae increased, photosynthesis began to bring oxygen to the earth. About 200 million years ago, there was only one united ancient land in the world surrounded by the ocean, the ancient Pacific Ocean. Later, as lava surged up from the interior of the earth, the ancient land was divided into pieces, and new basins were formed where they were separated. Seawater poured in, becoming the Atlantic Ocean and Indian Ocean today, and the ocean gradually evolved into what it is today.