The Great Conjunction: Jupiter and Saturn's 20-Year Meeting

A great conjunction happens whenever Jupiter and Saturn appear to meet in the sky, roughly once every 19.9 years, the slowest recurring pairing either planet makes with anything visible to the naked eye. It has carried outsized weight in astrology for two thousand years, for the simple reason that until telescopes found Uranus and Neptune, Jupiter and Saturn were the two slowest, farthest planets anyone could track.

How Two Orbits Produce a Great Conjunction Every 20 Years

Jupiter completes an orbit in 11.86 years, Saturn in 29.46. Their conjunction, the exact moment they share the same ecliptic longitude as seen from Earth, recurs on a synodic cycle of about 19.85 years, the beat produced by the gap between the two orbital speeds rather than either one alone. Because that cycle isn't a clean fraction of the zodiac's 360 degrees, each successive great conjunction lands roughly a third of the way further around the sky than the last, not on top of it. Medieval astrologers tracked the pattern this produced: three conjunctions in a row landing in signs sharing one element, a grouping they called a triplicity, earth or air or fire or water, before the sequence drifted into the next element entirely, a shift they called the Great Mutation, spaced roughly two centuries apart.

The Closest Meeting in Four Centuries

On December 21, 2020, Jupiter and Saturn closed to about 0.1 degrees apart, six arcminutes, close enough that the unaided eye read them as almost one point of light. Nothing had put the two planets that close together in the sky since July 1623, and nothing had put them that close and easily visible from Earth since March 1226. Jupiter, currently transiting Leo, and Saturn, sitting in Aries, will not share a zodiac sign again until their next meeting in 2040.

A Star of Bethlehem Candidate

In 1614, Johannes Kepler proposed that a triple conjunction of Jupiter and Saturn in Pisces during 7 BCE, three separate meetings within one year caused by Jupiter's retrograde loop, might explain the Star of Bethlehem. The astronomy behind the proposal is solid: that triple conjunction did occur. Whether it is actually what the gospel account describes remains one hypothesis among several competing ones, including a Venus-Jupiter pairing a few years later, and no consensus has settled it either way.

What Makes a Jupiter-Saturn Conjunction "Great"?

It earns the name because Jupiter and Saturn were, for most of astrology's history, the outermost planets known to exist. Mundane astrology, the branch that reads world events rather than individual lives, used their infrequent meetings to time the rise of dynasties and religious movements, on the logic that a conjunction between the planet of expansion and the planet of structure marked the start of whatever era followed. A conjunction between faster planets, by comparison, was never treated as more than a passing week's weather.

Whether your own chart carries a version of this pairing is worth checking directly. Natal charts show a Jupiter-Saturn conjunction as a genuine placement, not just a headline event two decades apart.