Four billion years ago, there was three earth in the solar system? Scientists have discovered that the birth of the human race is an unrepeatable miracle!

In fact, there are plenty of planets in the universe with such conditions, such as Kepler 452b, Glieser 581D and Proxima Centauri B, all of which are rocky planets in the habitable zone where intelligent life is likely to be born. However, the actual conditions on the surface of these planets are not yet known because of the distance. At present, limited by the level of human science and technology. There has done not have discovery of extraterrestrial life.

In addition, a large number of interstellar organic molecules exist in the infinite space, and these substantial numbers of interstellar organic molecules are absorbed by many rocky planets, so that life does not lack nutrients. There are some primitive microbes that are so hardy that they can even travel through interstellar space, they can fly to other suitable planets, survive and reproduce, like a blown dandelion, spread around to survive and reproduce, like an advanced colonizer, alien life may exist just below the surface of Mars. For example, sea life comparable to Earth's deep ocean could also exist in the deep ocean beneath the surface ice sheets of Europa, Callisto, and Titan.

There may be many kinds of life in the universe, but the species that can create civilization are probably very few, because life is a very complex process that is subject to a lot of uncertainty, and it is rare for a species like Earth to provide billions of years for it to develop. Although the Earth has suffered several mass extinctions, biological species continue to develop in various forms, so the speciation of intelligent organisms is very difficult, because human science and technology are relatively backward, we do not know what is going on in the deep space.

Humans may have than those more advanced than we are, the scientists to test this idea, constantly launch into space probe, according to the exploration of large amounts of data, finally came to the conclusion that in 4 billion years ago, there are three exists in the solar system, earth may have life in them was born, we are now the earth is one of them. The surfaces of these three planets, composed of solid metal and silicate, are development planets. Over the past few decades, we have sent numerous unmanned probes to Venus and Mars, and scientists have found that their conditions are very bad.

While Venus is very hot, Mars is extremely cold and has no oxygen, at least in such an environment, scientists have found no evidence of other life. So what would be Venus and Mars have looked like four billion years ago? Now why become barren planet, suitable for living planet is only the Earth? Like the earth, they operate in a livable environment, as measured by the intensity of sunlight. Based on current indications on Venus and Mars, astronomers speculate that Venus and Mars may have had an ocean of liquid water four billion years ago.

For the first few years of its existence, Venus was a warm, wet planet, and life could have arisen in a primordial ocean. It could have been carbon-based life, like life on Earth, or other forms of life, but Venus was relatively close to the sun and could have produced a lot of melted water. Due to the temperature rising of the sun, Venus is becoming more and more heat and evaporate, Venus volcanic activity continues to release carbon dioxide, a strong greenhouse effect, oxidation of carbon in the absence of ocean, won't be locked, they came into the signs of global warming in the air, temperature on Venus is higher and higher.

On Earth, the deep sea, green plants and minerals absorb huge amounts of carbon dioxide, so the Earth is not prone to dramatic global warming, which would cause the temperature to increase. Eventually melted water on Venus would evaporate completely, and with it, most likely, any living species. While life is not possible to exist on the surface of Venus, scientists think there is some alien life, perhaps in its atmosphere. In Venus's relatively high air, with moderate atmospheric pressure and temperatures, organic compounds could have been born, and life could have evolved, and it could have been a livable planet.

Right now, the Martian landscape appears to have been a lot of water scour, and some iron ore, which can only be produced in an environment with water. All this evidence relates to the existence of large amounts of liquid water on ancient Mars. So how did Mars become inhospitable to life? A huge basin currently exists in the northern polar region of Mars, where the surface is equivalent to two-fifths of the surface area of Mars, created by a major impact.

Research shows that the huge basin, about 3.9 billion years ago, the North Pole of Mars suffered a dwarf planet hit, about 2000 km in diameter Mars kernel is completely changed, in the big collision led to Mars magnetic field almost disappeared, the Martian atmosphere without the protection of the magnetic field, liquid water and with continued volatility, Mars soon into a barren land. There is almost no atmosphere on Mars today, but some water ice remains in the polar regions.

In addition, some seasonal liquid water may be discovered in some parts of Mars. This water is also extremely salty, and it can temporarily remain liquid in the unfriendly environment of Mars. The average temperature on Mars is -63 degrees Celsius, which is extremely low. If humans want to colonize Mars in the future, the first thing they need to do is to restore the magnetic field of Mars and generate huge amounts of greenhouse gases to heat the planet and meet its solid water. Mars is much smaller than Earth and would have cooled from its molten state much faster than Earth, so liquid water would have appeared earlier on Mars, suggesting that life on the planet might have evolved much earlier.

Presumably, when Mars is hit by another celestial body, the rocks that are blown away are likely to carry Martian life into outer space, and then fall to Earth and become the origin of life on Earth. In addition, scientists have once found traces of life in a Martian meteorite, proving once again that Mars was the birthplace of life on Earth. Nevertheless, the evidence is still far from convincing. So far on Mars, Curiosity has detected carbon-containing organic matter in some rock formations.

That means life could have existed on Mars in its ancient past, and possibly even today. Billions of years ago, instead of going extinct, they went underground and evolved a unique survival system. Compared with Venus and Mars, our Earth has been blessed by nature and has always been a habitable planet. In the future, Earth will may be no longer part suitable for human habitation, just like Venus and Mars. What do you think?