system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: do laser beams have a ending when pointing them at the sky? I have a green one and point it at the sky at night and it looks short but idk if it really is.
gpt
Another factor is diffusion. Lasers are a focused beam of, ideally, a single light wavelength. 

In actuality the consumer product you have will diffuse, or defocus, over distance. So eventually it will be relatively undetectable. 

That said, your device will NOT experience this at any distance you will be able to measure. Its beam remains coherent (focused) and highly dangerous well beyond what you can see.

For that reason you should never point it skyward. It will be dangerous to aircraft, specifically the pilots, that you may not see. A report of a laser by a pilot is always investigated rapidly and will result in serious charges. 

Lasers are cool. Please be safe with it.