The moment has arrived. Keep your fingers crossed for clear skies tonight and whatever else you are doing, make the attempt to see the extraordinary conjunction of Jupiter and Saturn.
Known as a grand conjunction, the line of sight to each planet is now lying so close to one another that you will probably not be able to distinguish them as separate objects. Find somewhere with a clear south-western horizon and look for the brightest thing you can see, low in the twilight sky: that object will be both Jupiter and Saturn.
The chart shows the view looking south-west from London on 21 December at 1700 GMT, but the conjunction will be visible around the world soon after the sun goes down. Don’t be late, the planets will set early in the evening.
The last time the planets were this close from our viewpoint on Earth was almost 400 hundred years ago on 16 July 1623. Of course, the planets aren’t really close together, Jupiter is currently 886 million km (551 million miles) from Earth and Saturn is another 733 million km beyond it. They happen to lie in the same direction. The conjunction is visible from most parts of the planet.
This article was amended on 21 December 2020 to correct the figures cited for the distances of Saturn and Jupiter from Earth.