This causes fluctuations in the brightness of the star as it refracts through different layers of the atmosphere.
The effect is that we get a smeared image of the star instead of a bright point of light.
To solve this problem, an artificial guide star is created.
A beam of laser is projected up through the atmosphere.
Below are some magnificent images of laser beam shooting out of observatory domes.
Astronomers observing the centre of the Milky Way using the laser guide star facility at ESOs Paranal Observatory.
A Laser Guide Star (LGS) System at Gemini Observatory.
