A stunning lunar halo lights up the sky above the European Southern Observatory’s Very Large Telescope in Chile. More common than rainbows, this simple natural phenomenon is a geometrically brilliant example of refractive power, where moonlight is refracted by tiny ice crystals and water droplets acting as prisms in the wispy cirrus clouds. Lunar halos appear quite large, measuring 22 degrees across the sky.
Note that in this image, one of the Very Large Telescope’s individual telescopes fires a quartet of laser beams into the sky. Far from being light pollution, these lasers create artificial stars in the sky when reflected off dust and molecules high in the atmosphere, creating a guiding star for the telescope to focus on and mitigate the atmospheric turbulence that the Light can blur from objects beyond. Image: Juan Carlos Muñoz-Mateos/ESO.
https://astronomynow.com/2022/06/15/moon-ring/ Moon ring shines bright over the VLT – Astronomy Now