What is the farthest point of light that is emitted by a torch?

  • If I focus my torch into the night sky,what would be the farthest point the light can reach? Recently I looked at the night sky and noticed a light spark moving around the clouds for about 15 min.After observation I jumped into a conclusion that its probably because of the light house near by or any powerful light emitter.


    Why did you post this question in this SE? XD

    @Py-ser It relates to "Astronomical observations, for all celestial objects across the entire spectral range". Though the light source is actually Earth based, it is still a perceived astronomical phenomenon. I think it is a good and relevant question.

    In US English, a handheld battery-powered light is called a "flashlight"; the word "torch" usually refers to a more primitive *burning* light source.

  • If you point a flashlight up, then the light will reach as far as the other ends of the universe, if one has a sensitive enough measuring device, so long as it is not absorbed. Of course, said device might require a lot of work, and a huge telescope. Lights can easily be seen by satellites, but it would take a huge telescope to see a single light from, say, the Moon, and even larger the further you go.



    In the case of your moving light, I would suspect a laser of some kind. Lasers are focused enough where one could easily see a reflection from the clouds, and pretty focused as well. It could be a moving light source, such as a plane or balloon of some kind as well.


License under CC-BY-SA with attribution


Content dated before 7/24/2021 11:53 AM

Tags used