Constellation knowledge why the moon has different phases.

The moon is a satellite orbiting the earth. As the closest celestial body to the earth, the moon is relatively familiar to us. Whenever night falls, the moon will hang in the sky. Then let's use constellation knowledge to reveal why the moon has different phases.

Why does the moon have different phases?

As the moon moves a long distance from west to east in the starry sky every day, its shape is constantly changing, which is the phase change of the moon, called the moon phase.

Because the moon itself does not give off light, half of the sphere facing the sun is bright and the other half is dark under the sunlight. Because the position of the moon relative to the earth and the sun has changed, the side irradiated by the sun sometimes faces the earth and sometimes faces away from it; Sometimes the part of the moon facing the earth is larger, and sometimes it is smaller, so there are different moon phases.

The disappearance of the lunar magnetic field

Early moon experts said that the moon's magnetic field was weak or no magnetic field at all, while samples of moon rocks showed that they were magnetized by a strong magnetic field. This is another shock for NASA scientists. Because they always assume that the moon rocks are not magnetic. These scientists later discovered that the moon used to have a magnetic field, but now it doesn't.

In the study of rocks brought back from the moon by American Apollo astronauts, scientists found that the magnetic field around the moon is less than11000 of the earth's magnetic field, and there is almost no magnetic field on the moon. However, research shows that the moon once had a magnetic field and then disappeared.

The magnetic field of the moon ranges from 50-10 billion years after its birth to 360-39 billion years. However, when it appeared 600-900 million years later, the magnetic field suddenly disappeared. The earth's magnetic field originates from the earth's core. Scientists believe that the earth's core is divided into an inner core and an outer core. The inner core is solid and the outer core is liquid. Its viscosity coefficient is very small, and it can flow quickly, producing induced current, thus producing magnetic field. In other words, the magnetic fields of all planets are generated by induced currents.

According to the analysis of rocks on the surface of the moon, there is no core on the moon that can produce induced current. On the contrary, all the evidence shows that the surface of the moon is a dissolved shell, an "ocean" formed by flowing lava fluid, and later it became what it is today due to cooling. At first, almost all astronomers thought that man had discovered the ocean on the moon. In fact, the dark part of the moon is formed by the cooling of lava.

So where does the magnetic field come from? A physics expert group led by Professor Dreckmann from the Department of Earth Planetary Science of the University of California, USA, conducted a three-dimensional simulation experiment on this subject. After the experiment, they finally came to a conclusion. According to the team, light and flowing rocks form an "ocean" of lava, and when they drift to the surface of the moon from below, a large number of heavy radioactive elements such as thorium and uranium remain under its surface.

When these elements collapse, they release a lot of heat, which heats the inner core of the moon like an electric blanket. The heated material forms convection with the surface of the moon, resulting in induced current. At this time, the lunar magnetic field is also produced. But when the radioactive elements collapse beyond a certain point, the convection phenomenon stops and the induced current disappears. It is because of this change that the magnetic field of the moon finally disappeared.