In November 1974, Pioneer 11 became the first spacecraft from Earth to visit Jupiter. Humans have likely been fascinated by this bright spot in the sky since we started looking up to the heavens, and our oldest astronomical records show regular observations of this huge planet. Then early in 17th-century Italy, Galileo built his telescope and identified the Jovian bands along with four moving dots. Those are the moons Io, Europa, Ganymede, and Callisto.
Clocking in at 383 Earth masses, Jupiter is the most massive member in the solar system, and NASA so far has sent five missions to study it. It’s a hard planet to visit, though: Aside from our Sun, Jupiter has the largest magnetic field in the solar system. Such an extreme radiation environment can easily fry life-sustaining electronics that get near it (“near” here meaning millions of miles). This magnetic field is so large, in fact, that if you could see it in visible light, it would appear as the size of the full moon in our sky—even though the giant planet itself is roughly 500 million miles from Earth.
This week we’ll tag along with a few different space missions to Jupiter, taking its grandeur from all angles and in unprecedented detail.
One of Pioneer 11’s first photos is of Jupiter and its north pole. (It’s a funky angle, which is how the north pole ends up at the bottom of the shot.) The terminator–the line between Jovian day and night—also cuts across this polar region. When Pioneer snapped this pic, the spacecraft was just beginning to use a gravity assist from Jupiter to slingshot out toward Saturn. Bonus: The retro image quality gives those iconic bands a groovy ‘70s vibe.Photograph: NASA Ames
Flash-forward to 2016. The powerful Hubble Space Telescope in orbit around Earth takes an astoundingly detailed look at the same planet: You can see its telltale bands, the iconic Great Red Spot, and smaller individual storms. The disco party at the north pole is an aurora, same as we have here on Earth—created when highly charged particles from the Sun crash into Jupiter’s magnetic field.Photograph: NASA/ESA/J. Nichols (University of Leicester)
Just a few years after Pioneer 11 flew its initial reconnaissance mission, NASA launched the twin Voyager spacecraft to explore the outer solar system. When Voyager 2 arrived “at” Jupiter (well, it was about 8 million miles away), here’s one of the photos it took. It shows the planet and Io, its smallest and closest Galilean moon (named so since Galileo discovered four of them). Io is covered in volcanoes and is the same size as our own rocky satellite.Photograph: JPL
NASA’s Juno spacecraft goes around the planet Jupiter every 52 days; its orbit is elliptical, swooping in close and then swinging back out. This past May Juno approached and snapped this dizzying image of the planet and its seemingly endless storms. Scientists have always known Jupiter hosts the most puzzling storms in the solar system, but it turns out that some Jovian storms are invisible to the naked eye. Using its infrared camera, Juno revealed layer after layer of cyclones—a clue that the forces creating these clusters of storms might be more complex than initially thought.Photograph: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill
The Juno spacecraft is in a polar orbit around Jupiter, which means that it flies over the north pole, and then ducks under the south pole. These two active regions are of great interest to the scientific community because of the high concentrations of cyclones and other storms prevalent in the region. Those storms have slightly different mechanics than their kin on Earth for three reasons: The planet is a gas giant and an enormous one; the atmospheric pressure at its “surface” is almost three times more than that on Earth; and the atmosphere is mostly hydrogen and helium, instead of the oxygen and nitrogen that surround our solid little planet. Photograph: NASA/JPL-Caltech/SwRI/MSSS/Gabriel Fiset
Typically clad in tans and creams, Jupiter is falsely colored here in rose by Juno, which lets us notice a pretty interesting feature. Look at the center of the image, and you’ll see an elongated clump of white clouds. These are upper atmosphere clouds, which no one had ever seen in Jupiter’s atmosphere until Juno showed up.Photograph: NASA/JPL-Caltech/SwRI/MSSS/Matt Brealey/Gustavo B C
Eager to venture beyond Jupiter? Explore the full space collection here.
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