When you look at a photograph of Jupiter, your eyes are immediately drawn to a massive, swirling, crimson oval in its southern hemisphere. This is the Great Red Spot, an anticyclonic storm of epic proportions that has been raging for centuries.
How Big is the Great Red Spot?
To understand the scale of this storm, we have to look at our own planet. The Great Red Spot is approximately 10,000 miles (16,000 kilometers) wide. That means it is roughly 1.3 times the size of Earth. You could literally drop our entire home planet into the storm, and it wouldn't even touch the edges!
Winds of Fury
Calling the Great Red Spot a "hurricane" is a severe understatement. While the strongest hurricanes on Earth might reach wind speeds of 200 mph, the winds howling around the outer edge of Jupiter's storm peak at around 268 mph (432 km/h).
Unlike earthly storms that are fueled by warm ocean water and eventually break apart over land, Jupiter has no solid surface. The Great Red Spot is sandwiched between two powerful jet streams that move in opposite directions, acting like a cosmic conveyor belt that constantly feeds the storm's momentum.
Is the Storm Dying?
Historically, observers in the late 1800s measured the spot to be much larger—about 25,000 miles across, or three times the size of Earth! Over the past century, and particularly in the last two decades, astronomers have noticed that the Great Red Spot is slowly shrinking and becoming more circular.
While it is getting smaller in width, data from NASA's Juno spacecraft suggests that the storm might actually be growing taller as it shrinks in diameter. Will it eventually disappear entirely within our lifetimes? Scientists aren't sure, making every observation of this ancient storm incredibly precious.
