Paranal mirror cleaning

Optical engineer Jaime González cleans the tertiary mirror, M3, inside UT2 "Kueyen" — one of four Unit Telescopes that comprise ESO's Very Large Telescope (VLT), situated at Paranal Observatory in northern Chile.

All of the telescopes' mirrors must occasionally undergo cleaning to ensure the highest quality astronomical images. A simple burst of pressurised carbon dioxide (CO₂), seen here as the white cloud, removes unwanted dirt from the mirrors.