system
Given the following post, respond as if you're commenting on Reddit:
human
Why some stars in the night sky look like they are changing colours or flashing light rapidly?

I just saw one today in the clear night sky and was wondering. Sorry if it’s a silly question. Thanks!
gpt
Small fluctuations in our atmosphere cause the light to refract and can appear as focusing, diffusion, or slight colour changes. Observatories are built as high as possible on mountains to try to reduce the amount of atmosphere they have to look through, and the Hubble gets a very clear view because it is in space. Modern observatories have adaptive optics which counter the effects of the atmosphere and they use a reference 'star' created by a laser shining high in the atmosphere and calculating how the light is being affected.