What We’ve Learned from Juno’s Latest Laps Around Jupiter

Jupiter’s (cyclonic) south pole, taken by the Juno spacecraft. NASA, 2017.

You may have seen the gorgeous pictures of Jupiter floating around your twitter feed, but they only scratch the surface of the incredible discoveries the Juno spacecraft has sent back to Earth. “Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian [pertaining to Jupiter] science, and there is always something new,” says Scott Bolton of his experience as principal investigator aboard the 10-year-old Juno mission

Since July 4, 2016, when the Juno spacecraft was close enough to Jupiter to complete one orbit every 53 days, Bolton has overseen data collection and analysis from each of the eight instruments aboard Juno, including optical, infrared, and ultraviolet telescopes. The data files are so large that they can take over a day to transmit to Earth and much longer to analyze.

Juno was designed to answer our basic questions about Jupiter, a planet relatively close to Earth in our solar system. These include the composition of its prominent cloud formations and how its extraordinarily strong magnetic field — second only to the sun in our solar system — affects its moons and emission at different wavelengths. The spacecraft’s elliptical orbit enables mapping of the core mass distribution, the pressure-varying gravitational field and polar magnetic field and aurorae — all of which inform us of Jupiter’s formation and evolution. 

The first results from the Juno mission were released in October of 2016, revealing that the depth of the colorful stripes of clouds is much deeper than scientists had theorized. The infrared telescope aboard Juno captured pictures of the planet’s deeper layers, confirming the continuation of the gaseous stripes beneath the visible outer surface. September 2017 brought yet another discovery, and with it, an entirely new field of study focusing on Jupiter’s magnetic field. Jupiter’s auroras, which are not actually visible at optical wavelengths, puzzle scientists in their formation, as they are unlike that of the northern lights we experience on Earth. However, upon comparisons with the Voyager results — another NASA mission to pass Jupiter — researchers connected the observed “torus,” or ring, of plasma around Jupiter’s equator to be the source of the charged particles that produce aurorae at Jupiter’s poles. 

Recently, the Juno mission has been winding down, completing its last few orbits before it deorbits into Jupiter in July 2021. Though its time of actively collecting data will soon come to an end, the impact of the Juno mission will continue to be seen as researchers analyze and present its data for years to come.

This article was edited by Cat Kim and Hedy Goodman.