Anyone who’s seen a picture of Jupiter has stared — for more than a few seconds — at that giant, massive red splotch in the planet’s southern hemisphere. It’s the bloodshot eye of a violent storm bigger than Earth that’s been raging for centuries.

the Great Red Spot is the smallest it’s ever been

Amy Simon

That’s less than half of historical measurements.

In the 1800s, astronomers estimated the spot was about 25,000 miles wide. But since the 1930s, observations have suggested it’s getting smaller. Voyager 1 and 2 fly-bys in the late 1970s placed the squinty spot at just 14,500 miles across — or the equivalent of two Earths (Earth’s diameter measures 7,918 miles wide). But the splotch has gotten even smaller. In