On December 21, after sunset, it will be possible to observe a “double” system of planets – Jupiter and Saturn, which will be visible in close proximity to each other. Such an event will occur for the first time since 1226, and it can be seen anywhere on Earth.

In December, there will be a very rare astronomical event: the planets Jupiter and Saturn will approach at an exceptionally short distance. The phenomenon is exceptionally rare conjunction and it will occur this year 2020 for the first time since the Middle Ages.

“On the evening of closest approach on Dec 21 they will look like a double planet, separated by only 1/5th the diameter of the full moon,” says Patrick Hartigan from Rice University.

Scientists who have been observing this process since the summer have came to the conclusion that from December 16 to December 25, Jupiter and Saturn will share an apparent distance less than the diameter of the Moon (meaning the “alignment” of the planets from the position of the terrestrial observer). And on the evening of December 21, they will almost “merge” at all: the distance will not exceed more than one fifth of the lunar diameter. In addition, not only the planets themselves will be visible, but also their largest satellites.

The scientist admits that the alignments between these two planets occur every 20 years, but “this conjunction is exceptionally rare because of how close the planets will appear to one another.”

To observe the historical planetary phenomenon, it is best to be somewhere near the equator, but if the skies are clear, then the alignment should be visible from almost anywhere on Earth.

The two planets will be seen in the night sky for an hour after sunset each night between December 16 and 25, according to astronomers.

However, it won’t be the closest possible conjunction: On March 4, 1226, Jupiter and Saturn got even closer.