How far can your laser pointer reach? If you aim it to the sky, will people in space be able to see it?

Takayuki Ohira, creator of the MEGASTAR planetarium projector, recently tried that out with a generic laser pointer. He posted the results on Twitter. He attached a class 1mW laser pointer to a telescope and pointed it at a building roughly 20 kilometers away to see if it could be seen by the naked eye. Check it out below:



Ohira was aided by Japanese astronaut Soichi Noguchi, who snapped a picture with his phone from the receiving end of the laser.


He then tweeted:

"If it can be seen by the naked eye, it can be picked up by a sensor, so if you were to embed a signal in it, you could use it to communicate. It's optical communication so gigabit levels should be easy."