What is the purpose of aliens reaching the earth?

At present, there are mainly the following six statements:

(1) Promote civilization: Aliens secretly guide human beings to a more civilized future and promote cosmic culture, such as ancient civilizations such as Egypt and Maya, which may be the civilizations left by aliens. In recent years, the fourth application of contact, that is, to convey some new ideas from aliens through telepathy, is called the new era thought.

② Rooting in the Earth: Aliens used to be earthlings and left when the variation of living environment could not adapt, leaving behind many splendid ancient civilization relics, such as the pyramids of Egypt and Maya, and the huge figures on the ground in Nazca, South America. Now they want to go back to the earth to visit those ancient ruins of civilization.

(3) Sightseeing: The living standard of aliens is extremely high and the technology is quite developed. They can travel all over the universe, and of course they will reach the earth, a beautiful blue planet suitable for the survival of cosmic creatures.

(4) Surveillance and vigilance: Human beings are bellicose, so aliens monitor human beings' use of destructive nuclear weapons to prevent public hazards, which will lead to the extinction of the earth and affect the peace of the universe.

⑤ Investigation resources: Aliens killed many livestock, even kidnapped humans as medical experiments, and explored various resources of the earth for a long time, often taking samples of plants, rocks and water to seek information or resources lacking on their planet.

⑥ Invasion and conquest: The earth is an extremely precious planet in the universe. When aliens can't survive on the original planet because of the natural environment or excessive population expansion and need to move out, they may take the earth as the migration target. Therefore, secretly spy on the military secrets, geographical environment and human data on the earth, and make plans for future military aggression and conquest of the earth.

From a scientific point of view, the above six statements are that aliens spend huge resources and sail long distances to reach the earth. Everyone who comes to the earth is unwelcome and must have a purpose. It is very likely that they will invade and conquer the earth as a colony, or even destroy mankind as a place to migrate. Humans must be vigilant to prevent alien invasion.

Throughout the ages, many people have witnessed UFOs, but the research on them has not made much progress, so many people are confused about this phenomenon or don't believe in UFOs at all. We believe that the UFO phenomenon is real, and it is not pseudoscience, but due to the limitation of science and technology, it has not been fully understood for the time being.