Could the "neglected" Venus have once been a habitable planet?

Which planet is the closest to Earth? It is Venus, which is only about 40.5 million kilometers away from Earth. So, which planet is the most similar to Earth? It is Venus again.

The similarities between Venus and the Earth are reflected in two aspects: one is "appearance" and the other is "behavior".

In terms of appearance, Venus' diameter is 95% of Earth's diameter, and its mass is about 80% of Earth's mass. In terms of behavior, Venus's orbital period is 224.7 days, which is relatively close to Earth's 365.24 days. It can be said that in the solar system, no planet is as similar to Earth as Venus, so people often call Venus Earth's "sister planet." Since it is a sister planet, why do humans seem to be not very interested in Venus? In fact, Venus was not neglected by humans from the beginning.

In the beginning, humans were very keen on exploring Venus, and the first spacecraft to explore Venus was Mariner 2 launched by the United States. It flew past Venus on December 14, 1962 and obtained the atmospheric temperature data of Venus.

After that, the Soviet Union followed suit and launched four Venus probes in succession, but the first three failed. Finally, in October 1967, Venus 4 successfully explored Venus. This was just the beginning, and then entered a Venus exploration boom that lasted for more than 20 years. The last time humans explored Venus was in 1989, when the United States used the space shuttle to launch the Magellan Venus probe in space. With the Magellan probe, humans obtained the clearest images of the surface of Venus and valuable data in history, but it was also from then on that humans lost interest in Venus.

Through the exploration of Venus, humans finally discovered that the similarities between Venus and the Earth are only superficial, and its interior is completely different from that of the Earth.

Venus has a dense atmosphere, and its atmosphere is completely different from that of the Earth. Its main component is carbon dioxide, so the greenhouse effect is serious. On the surface of Venus, the average temperature can reach 462 degrees Celsius, which is far beyond the limit that life can withstand, but this is not the most terrible thing. In the atmosphere of Venus, there are concentrated sulfuric acid clouds with a thickness of more than 20 kilometers, so concentrated sulfuric acid rain has become a common weather here. Among the known life forms, no life can withstand such a baptism. The environment of Venus is destined to make it impossible to become a habitable planet, and it does not have any transformation value, so it can only be neglected by humans.

If Venus looks and behaves so much like Earth, why is it so different inside?

In fact, Venus was not like this from the beginning. Even in the recent past, Venus was probably a habitable planet, and it was probably changed by an impact. Compared with other planets in the solar system, Venus is very special in two ways. One is its rotation direction, and the other is its rotation speed. All the planets in the solar system rotate from west to east, only Venus rotates in the opposite direction. Moreover, Venus rotates very slowly. It takes 243 days to complete one rotation, which is longer than the time it takes to revolve around the sun. Why is this so? The power of the planet's rotation comes from the conservation of angular momentum of the original nebula before the formation of the solar system, so the rotation direction of Venus must have been from west to east when it was first formed.

What can change the direction of a planet's rotation is a violent impact, so we can imagine that at some point in the past, a large celestial body collided with Venus and changed the angular momentum of Venus, so Venus began to rotate in the opposite direction, and the rotation speed was very slow.

What caused the dramatic change in Venus' environment was not the impact or the change in the direction of rotation, but the change in rotation speed. Venus has an iron core, but almost no magnetic field. Why? It is because Venus rotates too slowly, that is, the change in Venus' rotation speed directly led to the disappearance of the magnetic field. Without the protection of the magnetic field, Venus' atmosphere was gradually blown away by the solar wind.

After the atmosphere was blown away, the liquid water on the surface of Venus quickly disappeared.

The ocean exists above the surface. The disappearance of the ocean caused a huge change in the surface pressure, so the crustal activity intensified, and volcanic eruptions began one after another. Scientists estimate that there are millions of active volcanoes on the surface of Venus. A large number of volcanic eruptions brought a large amount of carbon dioxide and other acidic gases, so Venus has a new atmosphere, and the speed of Venus's atmosphere is faster than the speed of being blown away by the solar wind. Although the dense atmosphere reflects most of the sunlight back, the atmosphere composed of carbon dioxide has an excellent heat preservation effect, so the greenhouse effect on Venus is serious, and soon a high temperature of 462 degrees Celsius is bred. This is the whole process of Venus changing from a habitable planet to a "hell planet".

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