May - Moon halo at La Silla

When light from the Sun or Moon passes through cirrus clouds high up in the Earth’s atmosphere, a halo such as this is formed. The tiny crystals that make up these clouds act as miniature prisms, changing the direction of the light that passes through them.

In the foreground of this angelic scene sits ESO’s 3.6-metre telescope which hosts the HARPS instrument. In 2016, HARPS was one of two instruments that detected the exoplanet Proxima b, which orbits around the star closest to the Sun, Proxima Centauri.