People around the world looked up Monday for a once-in-a-lifetime spectacle, as Jupiter and Saturn, the solar system’s two largest planets, appeared closer to each other in the sky than they have in nearly 400 years. According to NASA, it’s been even longer — almost 800 years — since the planets aligned at night, timing that gave almost everyone on planet Earth the chance to observe the astronomical event known as a “Great Conjunction.” Last night’s event was made even more unique by the fact that it fell on the winter solstice, the longest night of the year, a “rare coincidence,” NASA astronomer Henry Throop said, as “the date of the conjunction is determined by the positions of Jupiter, Saturn, and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis.”
Here are some photos of the December 21 near convergence, when the giant planets appeared a tenth of a degree apart. (In reality, the two planets are hundreds of millions of miles apart.) It was a rare treat: an alignment similar to Monday’s reportedly won’t come until 2080, with the following close conjunction 337 years later, in the year 2417.