Although humans entered space as early as 1961 and landed on the moon in 1969, until today, humans' understanding of the interior of the earth is actually not as good as that of space.
In the field of science, getting into the ground is far more difficult than going up to the sky. The Kola ultra-deep borehole drilled by the former Soviet Union was only 12 kilometers deep, and it didn’t even penetrate the crust at the substratum level, let alone the mantle and core.
Under the circumstances that it is difficult for drilling technology to pry into the deep secrets of the earth, the scientific community began to use seismic waves to map the interior of the earth, and soon they made new discoveries:
The research team of the University of Alabama in the United States recently used seismic waves to detect the existence of a huge ancient seabed relic inside the earth. It is located at the junction of the mantle and the core, and the depth reaches an astonishing 3200 kilometers. Considering that the earth’s radius is only 6371 Kilometers, the newly discovered ancient ruins almost enveloped the entire core of the earth.
But why is it that such a large relic has not been discovered until now?
The answer is that this relic is hidden too deep. The discovery of the research team at the University of Alabama is based on three years of seismic wave data collection inside the earth, and the source of the data is 15 places in remote Antarctica. It took 3 years for 15 observatories to finally discover this relic hidden in the interior of the earth.
As a new area between the mantle and the core, the newly discovered ancient seabed remains are called the ultra-low velocity zone by scientists, with a thickness between 5 kilometers and 50 kilometers. During this time, seismic waves will become very slow when passing through this area, but why are ancient seabed remains buried deep inside the earth?
This problem can be traced back to the distant geological age. At that time, the collision and compression between the various plates of the earth were relatively frequent. The ocean at the junction of the two plates often served as a subduction zone. Underground subduction, part of the land that originally belonged to the seabed will gradually move in from the surface.into the earth's interior, and finally stopped above the earth's core and under the mantle.
While detecting this low-velocity region inside the earth, there is a data that the scientific community is particularly concerned about, and that is the temperature of the earth's core.
As we all know, the flow of liquid iron and nickel in the core region of the earth, which is the source of the earth's magnetic field, cuts the magnetic field lines, and the resulting planetary dynamo effect has been helping the earth to deflect against the solar wind, and all this The premise is that the core of the earth is hot enough.
Currently the proven core temperature is between 4000 degrees Celsius and 6800 degrees Celsius, which is basically the same as the surface temperature of the sun. These are all caused by the radioactivity of nuclear materials inside the earth. Over time, these After the radioactive elements lose their activity and become ordinary substances, the temperature of the earth's core will begin to drop, and the liquid iron and nickel will also solidify. Without them cutting the magnetic induction lines, the earth's magnetic field will gradually weaken or even disappear.
The earth without a magnetic field will face the solar wind from 150 million kilometers away. Today’s Mars is the final outcome of the earth after the magnetic field disappears, that is, from a blue planet to a into a bare rocky planet.
If human civilization is still there at that time, the best way out is to transfer from the earth to the planets outside the solar system, such as Mars that Musk is thinking about, and the many planets of Jupiter and Saturn on the satellite.
But from a long-term perspective, the earth or other planets in the solar system will only be a small part of the long history of human civilization in the future. Tsiolkovsky, the father of aerospace, said: the earth is the cradle of mankind, but Humans will not live forever in the cradle, they will first carefully penetrate the atmosphere, and then go to conquer the solar system.
Now it seems that the solar system is notThe end of human civilization, in the Milky Way with a diameter of 180,000 light-years, in the observable universe with a diameter of 93 billion light-years, the solar system with a diameter of two light-years is just a very small and remote world, and there is a vast universe waiting beyond it Human civilization went to explore.