The laser pointer is widely used in daily work and life. It is used as an indicator when explaining PPT in class, or as a marker for accurately indicating buildings from a long distance, or as a cat-playing artifact for people who play cats. The high-power laser pointer can ignite combustibles and cause fires. In addition, the laser pointer should not be directly directed at people's eyes, otherwise it will cause irreparable damage. The distance of the laser pointer depends on the power of the laser pointer, the number of particles in the air, the wavelength of the laser and other factors. I have a 50mW green laser on hand, which can easily shoot out of 1200 (measured on the map). The red 0.5-5mW The laser (that is, the laser emitted by the general red laser pointer mentioned above) can shoot about 500m. If you don't believe it, you can try it at night. If you want to shoot on the moon, the power of the laser is not measurable by mW and W...
The laser pointer is far away, and the accuracy is high, and it develops in a straight line. You can observe far away. If there is a chance to board the International Space Station, the brightness of the laser pointer launched from the Earth to the space station will drop to the same level as the brightest star in the night sky. Therefore, although the Laser pointer can irradiate to infinity in theory, the actual propagation distance visible to the naked eye is probably only a few hundred kilometers at most. So, can the laser pointer shine on the moon? As mentioned above, in theory, the light emitted by the laser pointer can reach infinity. The distance between the earth and the moon is about 380,000 kilometers. Assuming that there is no cloud, the laser will properly shine on the moon even if there is the influence of the earth’s atmosphere, but the scattered area of this light spot will be a bit large, almost It is the size of a small and medium-sized town, and the dim light spot cannot be seen clearly with the naked eye. Therefore, although the laser pointer can shine on the moon, it is impossible to use the laser pointer as the light source to "illuminate" the moon.