Since the existence of satellites, people have known for the first time that from space, the Earth is a blue-green planet – blue is the ocean, and green is the vegetation on land. Since then, whenever people think of the Earth, they will first think of this classic image.
But in reality, the image of the Earth is not eternal. In the long period of over 4 billion years before the landing of plants, the appearance of the Earth changed no less than 10 times, like the face changing masters in Sichuan opera.
4.55 billion years ago, Earth was just born – in simple terms, countless asteroids with a diameter of several kilometers collided with each other and converged to grow. In collisions, kinetic energy is converted into thermal energy, causing the originally rocky asteroid to melt into magma. At the same time, the radioactive elements carried by the asteroid itself begin to sink and converge into the Earth’s core due to the asteroid’s melting, continuously providing heat to the Earth in the form of radioactive decay. At this point, the entire Earth is like a magma ball, so there is no distinction between land and sea. At that time, the Earth may have grown like this.
The Earth was formed about 4.55 billion years ago, and the impact of countless asteroids turned it into a red magma ball. The ring in the picture is the result of the impact.
About 4.5 billion years ago or around 4.5 billion years ago, the Earth quickly began to cool down after its formation – this is easy to understand. A cup of hot water placed at room temperature would turn into constant temperature water, and the hot Earth would naturally cool down in the universe with an average temperature of -270 ℃. The bright magma cooled down and turned into black basaltic rocks, which covered the earth’s surface and made it black. Of course, this process occurs gradually. First, small black spots appear on a red background, then the black spots become larger and the red color recedes. Finally, the black color covers almost the entire Earth. In the end, the Earth as a whole became a black ball.
