This is how things have worked since Juno entered Jupiter’s orbit a year ago: JunoCam sends a bunch of images back to Earth, scientists and engineers upload them, and image-software gurus enhance them. The process has produced dozens of detailed, high-resolution photos of Jupiter’s puffy clouds and swirling storms, unlike anything found in science textbooks before. But there was something special about getting this close to the Great Red Spot, which Juno hadn’t passed over until this week.
The earliest observations of a massive spot on Jupiter date back to the 1660s, but historians and scientists don’t know whether people were actually looking at the Great Red Spot. The feature is large enough to be seen with Earth-based telescopes, and as technology improved, so did humanity’s image of the mysterious storm. The earliest photographs from the late 1800s and early 1990s showed a grainy, gray sphere.
It wasn’t until 1979 that humanity got its first real, close-up look. In January of that year, the Voyager 1 spacecraft started sending back photos of Jupiter on its journey through the solar system. It was still about 27.5 million miles from the planet then, but the level of detail in the imagery was astounding. “We’re extending our eyes into the outer solar system and into the unknown,” Bradford Smith, the head of Voyager’s imaging team, told The New York Times as Voyager approached the planet. “Not since Mariner 4 to Mars, some 15 years ago, have we been less prepared, less certain of what we expect to see.” Voyager returned thousands of beautiful, detailed images of the gas giant and its famous spot, which were turned into a time-lapse that revealed the motions of its cloud tops.
Hansen has been inching closer and closer to Jupiter for nearly 40 years. She was fresh out of college and working on Voyager’s imaging team at the time as “the assistant to the assistant to the assistant,” she explained jokingly. Scientists today aren’t as in the dark as they were in the early days of the Voyager mission, she said. But Jupiter can still surprise. “That’s part of the fun, really,” she said, before the latest Jupiter photos came back, “is not knowing what to expect.”
Scientists still don’t understand exactly what drives this giant storm, where winds can reach 400 miles an hour. The Juno mission is in a good place to provide some answers. I asked Hansen what it feels like to get within a few thousand miles of one of the solar system’s biggest storms after decades of observations. She pointed me to one of the images on JunoCam’s website, but it wasn’t of the planet. It was an illustration by an artist. A brown-haired girl with feathers down her back stands on a colorful lookout, staring up at a glowing, yellow-green planet.
“I would say, emotionally, this captures it for me,” Hansen said. “Just moving in closer and closer and seeing this world. And as you get closer, you don’t know what you’re gonna see. But you know it’s gonna be fantastic.”