Read: The massive mystery of Saturn’s rings
Saturn takes longer than Jupiter to orbit the sun, so every two decades, Jupiter catches up to it, a phenomenon that astronomers call a “great conjunction.” Some conjunctions appear cozier to us than others, thanks to differences in the big planets’ orbits from our own. The last time Jupiter and Saturn showed up this close together in the sky was in 1623, but the planets were near the sun then, so by the time it dipped below the horizon, they had gone with it. The last time the planets appeared this close and could be seen from the ground was in 1226.
That year, when construction of the Notre-Dame cathedral was still under way in Paris, the two planets were visible just before dawn. “You may very well have had artisans that were working on the stained glass that were going to work in the morning, looking up, and seeing it,” Patrick Hartigan, a physics and astronomy professor at Rice University, told me. Would they have noticed, as they stepped outside each morning, that the pair of milky-white points overhead had moved closer together with each passing day?
The great conjunctions of Jupiter and Saturn are some of the oldest observations in history, and they have long been associated with big and meaningful events: the ends of empires, the rise of new dynasties, chasmic cultural shifts. “From time immemorial, people have looked to the stars to help them explain the chaos of their present and the uncertainty of their future,” Ali A. Olomi, a history professor at Penn State who has studied how early observers thought about planetary conjunctions, told me. Thirteenth-century Muslim writers, for example, believed that the 1226 conjunction foretold the arrival of the Mongols in China. “By 1226, the Mongols were already on the scene, so they’re reading the writing on the wall, but they’re giving significance to those changes by saying, look, this was ordained by the stars,” Olomi said.
Read: Jupiter looks, um, different
Reading about tonight's event—a cosmic conjunction to end this year, of all years—and jumping to making meaning out of it might be tempting. That tendency has sharpened for many of us in 2020, and when unusual news has come out, especially anything related to the cosmos, we’ve treated it as a reflection of these months that sometimes seemed to exist out of time. The discovery of a black hole near Earth back in May seemed like some kind of sign. So did that monolith in Utah that seemed to come out of nowhere. The rareness of this conjunction will likely prompt some similar shivers.
Because while we certainly know a lot more about Jupiter and Saturn today than anyone did 800 years ago, the desire to draw meaning from celestial bodies and apply it to earthly matters hasn't disappeared. The instinct is hardwired; it’s why we see animals in the shapes of cumulus clouds, faces in the craters on the moon—and meaning in two bright planets in the night sky. In moments of crisis and anxiety, the urge to find explanations everywhere is particularly strong. It’s one reason that astrology has seen such a resurgence among Millennials in the past decade; as my colleague Julie Beck has written, people tend to turn to the zodiac in times of stress. “We’re always trying to look for meaning, and that’s something that doesn’t change, whether we’re talking about the 12th century or the 21st century," Olomi said.