Don’t blink! The earth is changing color

　　If I asked you what color the earth is, you would probably answer azure blue. In your mind, the earth is a mysterious blue, green, and white candy, with lush trees, turbulent oceans, and holy cloud and rain areas as its sugar coating. And the main color of the earth is undoubtedly a romantic azure blue, which is due to the fact that about 71% of the planet’s surface area is covered by oceans.
　　Would you be surprised if I told you that at this very moment, the Earth is not a bright, deep azure blue, but a dull grayish blue? In fact, in the 4.6 billion years since the birth of the earth, it has been quietly “changing color”. So far, the earth has changed through seven colors: dark red, black, green, purple, white, azure blue, and gray blue. The different colors are all witnesses to its difficult growth process. Don’t blink, let’s observe the colorful earth in different periods together.
　　Infancy – dark red, black, green
　　No one would have thought that the original color of the earth was dark red. Due to the violent collision and fusion, the earth’s temper was not very good at first, and the entire surface was covered with hot magma, which made the newborn earth look like a burning fireball. Since it is in its infancy, the earth has not yet grown hard land, only fiery magma lakes, so when the dark red magma flows freely, the earth naturally looks like a dark red planet.
　　As it grew step by step, the temper of the earth gradually became milder, and the body temperature also slowly dropped. The magma on the surface gradually cooled and solidified, forming the crust and mantle, which is the earliest basalt land. In ancient times, “xuan” refers to black, so the earth at that time seemed to have become a cool black.
　　After that, about 600 million years later, that is, about 4 billion years ago, due to evaporative cooling and alien comet impacts, a large amount of primitive water appeared on the earth, and almost 90% of the earth’s surface was covered by water. From the passionate fireball at the beginning of its birth to a gentle water polo, it also changed its color again. At that time, due to the extremely small oxygen content on the earth, a large amount of iron in the water could only react with hydroxide, sulfur, chlorine and other elements to form a substance called “anoxic rust”, which dyed the water With the refreshing green, the earth has officially become a green planet.
　　At this stage, the materials that changed the color of the earth were magma, basalt land and the first ocean. It seems that the earth first understood the truth of “the one who is close to vermilion is red, and the one who is close to ink is black”!
　　Adulthood—purple, white
　　After three times of color change, the earth seems to have adapted to its own “chameleon” identity. But no one expected that it would turn into a mysterious and romantic purple again.
　　The “Purple Earth Hypothesis” was first proposed at the annual meeting of the American Astronomical Society in 2007. The existence of a large number of microorganisms makes the earth appear purple. This is because there was no chlorophyll on the earth at that time, so early microorganisms used a substance called retinal to absorb sunlight for energy conversion, and retinal was located in the photosynthetic microorganisms of Halobacterium. The cell membrane of this microorganism absorbs purple light and reflects red and blue-violet light, making the earth an infinitely romantic purple planet.
　　Although there is no conclusive evidence that the earth was once purple, it is certainly the most reliable guess. And in recent years, the purple planet has been considered the most likely planet for life. In other words, during this period, there may have been life on the earth, and it is not alone!
　　But the good times didn’t last long. For a long time after the purple planet, about 2.4 billion years ago, the earth entered the most severe and longest ice age in geological history-the Huron Ice Age. The entire surface of the earth is covered by thick ice and snow, and it has lasted for 300 million years. The earth has become an ice ball that rejects life thousands of miles away. The reason for the rapid cooling of the earth may be that volcanic eruptions caused volcanic ash to cover the sky for a long time, or the proliferation of blue-green algae caused the rapid reduction of greenhouse gases on the earth. In short, the earth has become a frozen white planet.
　　After these two ups and downs of discoloration, the earth is about to turn into the azure blue we are most familiar with.
　　Adulthood – azure blue, gray blue
　　This period of Earth is probably the one with which you are most familiar. Yes, after 5 color shifts, Earth is a bright and calm azure blue due to about 71% of the surface being covered by oceans. A large amount of seawater will absorb the red light, orange light and yellow light with longer wavelength in sunlight, and most of the purple light with shorter wavelength will be reflected back, leaving only special blue light and a small part of green light. The cyan light can be fully scattered and refracted in the seawater, and the salt ions in the seawater greatly enhance the scattering of the light, so the seawater presents a beautiful blue color, making the earth a blue planet.
　　But if you think that the earth you are on is still blue at this moment, you are wrong. In fact, the earth is quietly changing color again, this time not because it has spawned new matter or produced huge geological changes. This time the discoloration was entirely caused by human activity. In other words, we are the ones who turned the color of the earth into a dirty gray-blue.
　　The blue earth is actually the healthy earth in our impression of blue and green. In recent years, due to excessive human activities that have severely damaged the earth’s environment, the areas of white and green have become smaller and smaller, replaced by blue and brown. This is because people’s pollution and over-exploitation of the earth have led to an increase in the area of ​​deserts and melting of icebergs. The ocean gradually flooded the land, and the ecological environment deteriorated sharply. The earth had no choice but to turn into a dull gray-blue planet.
　　If you know now, because human beings do not pay attention to environmental protection, the color of the earth is no longer the dazzling red, cool black, fresh green, romantic purple and holy white, and it is not even the deep blue in our impression. , will you feel a little sad? In fact, since the life of human beings was conceived on the earth, it has been continuously destroyed, and its beautiful colors are slowly fading.
　　According to the analysis of scientists, if human beings continue to behave like this, the earth will probably continue to change color again, but it will no longer change into a beautiful and pure color, but will only become darker and duller. Next time, what color will the earth turn into? Human beings are in control. What color do you expect to see on the earth?