The Great Conjunction of our system’s two biggest planets promises to be a truly extraordinary sight. Saturn and Jupiter will appear to come within touching distance of one another on Monday, December 21 – a conjunction that has not occurred for nearly 800 years. And if that is not reason enough to be excited, the planets might even appear to merge into one bright light resembling the Biblical Christmas Star.
According to EarthSky astronomers Deborah Byrd and Bruce McClure, Jupiter and Saturn conjunct once every 20 years or so.
Conjunctions describe the meeting of two astronomical bodies in our celestial dome.
But not all conjunctions are equal and this year’s event will be the closest since 1623 and the closest observable conjunction since 1226.
The astronomers said: “On December 21, Jupiter and Saturn will be only 0.1 degrees apart.
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“Some say the pair will look like an ‘elongated star’ on the date.
“Will they? Or will they look like a double planet?
“To know for sure, we’ll have to look and see. They’ll surely be an appealing and mind-expanding sight. “
Next week’s Great Conjunction will not be matched until March 15, 2080, so this might just be a once-in-a-lifetime event.
Stargazers in the UK can already see the two planets if they look out tonight.
Will the Star of Bethlehem rise on December 21?
At their closest, Saturn and Jupiter will only be one-fifth of a Full Moom apart.
As a result, some have argued the Biblical Star of Bethlehem that guided the Three Wise Men to the baby Jesus was a Great Conjunction in disguise.
However, not all Bible experts have accepted this theory.
The Reverend Dr M.W. Burke-Gaffney wrote in the Journal of the Royal Astronomical Society of Canada: “No matter how close together two planets come, – even if one planet should be so close to another as to occult it partly, – Wise Men would not mistake them for a single star.
“A few nights’ watching would show them separating, – as also they would have been seen to come together.”
And since no one has seen a Great Conjunction like this in nearly 800 years, there is no guarantee Saturn and Jupiter will appear to overlap to the naked eye.
But astronomers are certain the spectacle is one you do not want to miss, particularly if you have a telescope at hand.
NASA’s lunar expert Gordon Johnston said: “With a backyard telescope you should be able to see in the same field of view Jupiter’s four bright moons, Ganymede, Callisto, Europa, and Io, as well as Saturn’s brightly illuminated rings and largest moon, Titan.
“Seeing Jupiter and Saturn so near each other should appear spectacular by telescope and with the naked eye.”