At AWIPEV, we are shooting this green laser beam into the sky, we called that a lidar. The beam will reflect back to our observatory and it will give us an indication of what type of particles, the amount of them and also how high they are. Those particles play a big role into cloud formation and that the reason we are studying them.
We usually always shoot when there is a clear sky above us. I was playing around with my equatorial mount and I wanted to have a long exposure of the sky. The sky was indeed very clear. Therefore, the lidar was in operation. At some point, it became cloudy and you can see on the picture how the lidar is behaving when it encounter particles in the air. You can also see M45 (Pleiades) in the Taurus constellation (lower center in the aurora), Perseus constellation (in the middle), Auriga (lower left) and the laser is going through Cassiopea.