What are lasers used for at observatories?


Obviously the lasers aren’t reaching the the stars being observed, at least not anytime soon. So what are they doing?

In: Physics

One use is to detect atmospheric distortion of the light and adjust the telescope’s mirrors to compensate. Another is to measure the Earth-Moon distance using retroreflectors left on the surface by Apollo astronauts.

[Adaptive optics](https://en.wikipedia.org/wiki/Adaptive_optics) – adjusting telescopes on Earth to work around variations in the atmosphere, basically.