Can laser pointer Irradiate the moon?
Take a 5 MW (0.005 w) laser as an example. Go further and observe the light emitted by the pencil at a height of 12000 meters (assuming no interference from clouds). Your spots will be as bright as the moon. The average ground height of the international space station is 345 kilometers, while the moon is about 380000 kilometers from the earth. Use an ordinary pencil to illuminate the moon and remove obstacles in the atmosphere. The emitted light can still reach the lunar surface, but it will scatter in a large area, forming large and weak "light spots" that cannot be recognized by human eyes. The farther the object emits light, the larger the area of the spot and the darker the color. This is because although the laser is highly collimated, with the increase of propagation distance and air scattering, the laser will gradually diffuse and the brightness will decrease. No one on earth can see the moon at the same time. First, we must choose a time when most people can see the moon at the same time. Because 75% of the world's people live between 0 and 120 degrees east longitude. It can be a super power laser pen with enough energy to reach the lunar surface.
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A good laser beam is close enough to the moon, although when it reaches the moon, it will extend to a large part of the lunar surface. The atmosphere distorts the beam and absorbs some, but most of the light is still absorbed. In addition to safety, be careful with pencils. In the art museum, some paintings are afraid of light, so it is inappropriate to use a pencil. Laser pointer should not be used in zoos to avoid frightening animals. Some high-power lasers have thermal effect and can not be used continuously for a long time, especially solid-state lasers are more sensitive to temperature. Astronomers must be careful when using green lasers to point at stars. Do not use the marked stars for a long time to avoid others seeing the stars and taking pictures. In crowded public places, in order to avoid accidental injury to others, the use of laser pens should be stopped.
2021-08-27 10:14:50
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