大象传媒

An exciting event in astronomy is happening on the shortest day of the year - the 21st December - or winter solstice. Just after sunset, Jupiter and Saturn will appear close together in the night sky - and for the first time since the Middle Ages the two will look like a double planet.

Some people have speculated whether it could be the same light in the sky which became known as the 'star of Bethlehem', associated with the Christmas story.

Patrick Hartigan is a Professor of Planetary Science at the Rice University in Texas.

"This event is observable all the way around the world... go someplace where you would normally go to view a pretty sunset with a good horizon"

(Photo: Jupiter and Saturn are seen coming together in the night sky, over the sails of Brill windmill in England. Credit: Getty Images)