Lead
3.8 billion years ago, the planetary states of the solar system underwent a major change, which was another important watershed in the history of the solar system, and this year is arguably one of the most important years in the solar system.
3.8 billion years ago, the planets of the solar system underwent a late heavy bombardment phase, during which life on Earth, whether single-celled or basal, relied on its own ways to adapt to the environment of this period.
So what would the planets of the solar system look like 3.8 billion years ago?
What were the characteristics of the earth during this period?
Will the planets survive during this period?
How many questions are waiting to be answered?
1. The solar system 3.8 billion years ago.
3.8 billion years ago, the planets of the solar system were in the late stage of heavy artillery bombardment, and the ice and snow materials distributed in the asteroid belt and Jupiter's habitable zone were driven to gradually move inward, and finally formed a subduction process in the solar system, resulting in an increase in the collision events of the inner planets.
3.8 billion years ago, the earth was in a period of geological activity, that is to say, the earth's geological activities were quite active, and the lava layer continued to rise to form new plates, and then merged into the mantle, so that the earth's metabolism continued to run.
During this period, the earth also began to reproduce some basic life, but because the earth was still in a geologically active period, the decay period of the magnetic field at that time was only 200 million years, and then, the earth lost its own magnetic field.
This means that the atmosphere will also be corroded by the solar wind, and gradually lost in the following time, due to the lack of protection of the atmosphere, the earth's greenhouse effect is also lost, and the temperature gradually decreases, eventually leading to the earth's extremely bad temperature, and the earth during this period is also called "snowball earth" by scientists.
Of the gaseous planets in the solar system, Saturn and Jupiter occupy the vast majority of mass, while Earth's mass is almost negligible relative to Saturn and Jupiter, but 3.8 billion years ago, Saturn and Jupiter had about the same mass as the other planets today.
3.8 billion years ago, the positions of Saturn and Jupiter in orbit were not much different from now, but at that time the inner moons of Saturn and Jupiter, that is, Titan and Ganymede, were just a few asteroids, but now Titan has many rings and 27 moons, and Ganymede has six moons.
The size of the two gaseous planets 3.8 billion years ago was the result of an important collision event.
Titan was formed because a moon of the same Titan collided, while Callisto's moon was a small geologically active moon that collided with the same moon.
Among the six planets in the solar system, Saturn and Jupiter are more plated than Venus, Mars and Earth, because the inner layer of Saturn and Jupiter is relatively small compared to the surface, the proportion of the mantle and the outer layer is very small, mainly gas, which leads to a higher proportion of organic materials in the inner layer of Saturn and Jupiter, so 3.8 billion years ago, the inner core of Earth and Jupiter gradually emitted a lot of heat, which also provided energy for the geological activities of the moon.
The geological activity on the earth is also because of the heat in the earth's interior, which makes the mantle layer activated, so that the geological activity becomes very active, and 3.8 billion years ago, Venus has not experienced the large-scale red-hot phenomenon experienced by Mars, and at the same time, it has not experienced the geological activity that the earth has experienced, but is a normal habitable planet.
2. Venus, Mars, and Earth at that time.
Venus may have been a habitable planet with oceans and atmospheres 3.8 billion years ago.
Shortly after the formation of the solar system, the position of Venus was not close to the position of the Earth now, but relatively close to Jupiter, so the sum of the masses of Venus and Jupiter was not enough to attract ice and fog material from outer space, so the structure of Venus and Earth and Mars is similar.
In the late heavy artillery period of the solar system, the position of Venus gradually approached the position of the earth, and the radiation of the sun gradually intensified, so the water of Venus and the oceans on the earth were evaporated 3.8 billion years ago, and the atmosphere of Venus was gradually eroded.
The geological activities of Venus and the Earth are relatively similar, both of which are in the flow of lava in the plates of the earth's crust, and there are also collision events of continental plates, but because Venus is closer to the sun, the geological activity on Venus is more active, so the surface of Venus does not have as many craters on the earth, and even half of the craters are formed in the late heavy artillery bombardment.
The bedrock layer and crustal layer of Venus are relatively weak, so the geological activity on Venus is very active, and the movement speed of the plates is also very fast, on average hundreds of kilometers per year, so it is even more unlikely that there will be continents on Venus, so most of the area on Venus is covered by lava.
Because Venus does not have much atmosphere and has a relatively poor ability to trap particles, it is relatively young, averaging about 760 million years old.
The earth is in a geologically active period, but the oxygen content on the earth is high, but 3.8 billion years ago, the oxygen content on the earth was very poor, there are few minerals on the earth's crust, and carbonate minerals are also very scarce, and the short-lived radioactive isotopes contained in the olivine minerals formed by the combination of olivine minerals on the ground have long been gone, so there is no new heat injection on the earth, and the core of the earth has gradually cooled down, so the geological activities on the earth have become less active.
3.8 billion years ago, the oxygen content on the earth was very low, and there was no large land, most of it was covered by lava, and the oxygen of the soil was almost absorbed by these lavas, so the environment on the earth at that time was also extremely harsh, and it was not as habitable as Venus.
Mars was probably the most habitable planet in the solar system 3.8 billion years ago, with an ocean, atmosphere, and magnetic field.
Mars, like Earth, once had a large amount of liquid water, and Mars is also very rich in liquid water, so 3.8 billion years ago, Mars may be the most habitable planet in the solar system, Mars not only has oceans, but also a very thick atmosphere, and even a magnetic field.
In the solar system, due to the radiation of the sun, the ocean water of the inner planets is evaporated, which eventually leads to the gradual loss of water resources on Mars, and the geological activities on Mars have been close to stagnation about 4 billion years ago, and the magnetic field on Mars is almost gone.
4 billion years ago, because the heat in the interior of Mars was almost lost, the mantle layer of Mars was basically stagnant, so the atmosphere will gradually thin, which means that 4 billion years ago, the atmosphere on Mars was also gradually thinning, once the atmosphere of Mars was blown away by the solar wind, the water on Mars would be evaporated, because the gravity of Mars was small, and it was not even retained.
In the 40 years of Mars' atmosphere is thin and loses its magnetic field, a large amount of water will become gaseous and escape into space, until the atmosphere on Mars is blown away, and the lava and atmosphere on Mars will gradually form, which means that the ocean water on Mars is evaporated, the earth's crust is gradually formed, and the interaction between the earth's core and lava makes a small magnetic field on Mars, which also makes Mars have a large ocean 3.8 billion years ago.
In addition, there are also oceans composed of a large number of ice layers in Phobos and Earth, and a large amount of water is evaporated into space due to the small atmosphere of Phobos and Earth, and the difference between Mars and Earth is that the ocean and atmosphere on Mars are lost at the same time, so during the period of geological activity, the atmosphere of Mars is gradually thinned, and finally the ocean water on Mars evaporates 2 billion years ago.
But in Phobos and Phobos, most of the water is still preserved, and under the gravitational pull of Mars, it gradually converges at the south and north poles of Mars to form a massive ice formation, even 8,000 meters deep.
3. Potential extraterrestrial civilizations.
Venus and Mars experienced almost the same environment 3.8 billion years ago, but Venus has a large amount of ice in Mars and Venus lacks this condition, so it can be seen from this that the probability of a habitable planet on Earth and Mars is higher than that of Venus.
In the future, life may still appear on Mars and Venus, and life on Earth will most likely be discovered by human civilization, Venus and Mars were once representatives of habitable planets in the solar system, but now 3.8 billion years later, the Earth is the only planet that can reproduce life.
The civilizations on Mars and Venus may leave the solar system, and when the civilizations on Venus and Mars return to the solar system and find that the Earth has become the most habitable planet at this time, this plot is also very interesting.
epilogue
The situation in the solar system 3.8 billion years ago is amazing, and the history of the solar system will also be discovered in the future, life on the earth is also constantly evolving and developing, and the future will also be an unknown territory opened up by human beings.