Person viewing the planetary conjunction of Jupiter and Saturn (centre, right). A planetary conjunction occurs when two planets are seen close together in the sky as viewed from Earth. This was photographed a few days before the 'Great Conjunction' of the 21st December 2020 when the planets Jupiter and Saturn reached their closest alignment, a tenth of a degree apart. The last 'Great Conjunction' of Saturn and Jupiter as close together occurred over 800 years ago. Photographed near Alqueva Lake, Alqueva Dark Sky Reserve, Portugal.