The Great Kindness, also called the “Christmas Star” or “Star of Bethlehem,” has not been seen for 800 years.

According to Forbes, seeing this “once in a lifetime” percentage won’t happen again until 2080 and then sometime after 2400.

What is the Christmas star?

Jupiter and Saturn will venture close to each other and appear to collide later this month.

Gas giants will be closer in the night sky over Christmas than they have been in centuries.

But NASA said, in reality, you will be hundreds of millions of miles away.

The celestial scene should – if local weather permits – be visible from anywhere on Earth

The pairing is said to be last seen in the 13th century, and it is said that it will not happen again until around 2080.

Speaking to Forbes, astronomers said that such a “rather rare” alignment could be observed.

“The alignments between these two planets are rather rare, occurring once every 20 years or so,” said Patrick Hartigan, an astronomer at Rice University in Texas.

“This conjunction is exceptionally rare due to how close the planets are to one another.”

“You will have to go back to pre-dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky,” he added.

When will it be visible?

The “Christmas Star” will be visible to stargazers later this month on the evening of December 21st.

It has been reported that star-watchers should expect the celestial event to appear immediately after sunset.

It can be observed from anywhere on Earth where the sky is clear.

This means those in the UK should look out for the phenomenon from 3.53 PM onwards.

The “star” will appear very low on the horizon just after sunset, with a binoculars or telescope required.

Professor Hartigan noted that the planetary duo would appear low in the western sky at sunset every evening – and it should be bright enough to be seen during the twilight sky.

Professor Hartigan explained: “The further north the sights are, the less time they will have to look at the connection before the planets sink below the horizon.”

“By the time the sky gets completely dark in Houston, for example, the pairing will only be 9 degrees above the horizon,” he added.

“It would be manageable if the weather cooperated and you had an unobstructed view to the southwest.”