Juno Spots An Active Volcanic Eruption On Jupiter’s Moon Io


The end of the year has been quite intense for NASA’s Juno spacecraft. After wrapping up its 16th flyby of Jupiter, which marked the halfway point of data collection in the gas giant’s system — or the end of the first half of its prime mission, as previously reported by the Inquisitr — the space probe has embarked on the next phase of its extended journey.

With this latest milestone under its belt, Juno kicked off the 17th science pass over Jupiter and its plethora of moons with an amazing shot of Io, the innermost of the four Galilean moons.

On December 21, 2018, Juno captured a series of stunning photos of this small volcanic moon — the second smallest of the four, after Europa. The new string of snapshots reveals some tantalizing views of the moon’s poles, as well as evidence of an active volcanic eruption on Io, reports Phys.org.

Io is famous for its volcanic activity. According to Space Facts, the Jovian moon is home to around 400 volcanoes. In fact, Io is the most volcanically active world in the entire solar system — and could be housing many yet-undiscovered volcanoes, per a previous report from the Inquisitr.

The new Juno photos showcase areas of strong volcanic activity all throughout the surface of the Jovian moon — and have even managed to capture a volcanic plume streaming off into the cosmic night.

The four Galilean moons, shown from left to right in order of increasing distance from Jupiter: Io, Europa, Ganymede, and Callisto.
The four Galilean moons, shown from left to right in order of increasing distance from Jupiter: Io, Europa, Ganymede, and Callisto.Featured image credit: NASAWikimedia Commons/Resized

This fresh batch of Juno photos was taken with three instruments on board the spacecraft — the JunoCam, the Stellar Reference Unit (SRU), and the Jovian Infrared Auroral Mapper (JIRAM) — and offers a very enticing glimpse of Io’s turbulent temper. While it’s no secret that volcanoes are found aplenty on Io, its fervent geological activity has seldom been photographed with such clarity.

“We knew we were breaking new ground with a multi-spectral campaign to view Io’s polar region, but no one expected we would get so lucky as to see an active volcanic plume shooting material off the moon’s surface,” said Juno principal investigator Scott Bolton, a scientist at the Southwest Research Institute (SwRI) in Texas — and the vice president of the institute’s Space Science and Engineering Division.

“This is quite a New Year’s present showing us that Juno has the ability to clearly see plumes.”

The new Juno campaign at Io began with a string of three photos shot by the JunoCam between 12 p.m. and 12:20 p.m. UTC. Taken just before the moon entered Jupiter’s shadow, the pics capture Io half-illuminated by the sun, unveiling a volcanic plume spewing off of its surface.

Image of a volcanic plume on Io, taken by the JunoCam at 12:20 p.m. UTC on December 21, 2018, from a distance of around 186,000 miles.
Image of a volcanic plume on Io, taken by the JunoCam at 12:20 p.m. UTC on December 21, 2018, from a distance of around 186,000 miles. Featured image credit: NASA/SwRI/MSSS

Fueled by tidal heating that occurs deep within Io’s interior, the moon’s volcanoes produce ample plumes of sulfur and sulfur dioxide, plumes which rise well above the surface — reaching heights of a few hundred miles. The volcanic plume captured by the JunoCam is visible as “a bright spot seen just beyond the terminator, the day-night boundary,” notes Phys.org, citing the SwRI.

“The ground is already in shadow, but the height of the plume allows it to reflect sunlight, much like the way mountaintops or clouds on the Earth continue to be lit after the sun has set,” explained Candice Hansen-Koharcheck, the JunoCam lead from the Planetary Science Institute.

Once Jupiter moved in front of Io — plunging the Jovian moon into a total eclipse — Juno’s JIRAM instrument picked up a whole different view of the volcanic celestial body. A JIRAM photo taken at 12:30 p.m. UTC highlights the location of a volcanic eruption on Io by detecting the searing temperatures emanating from a volcanic hotspot.

JIRAM photo of Io showing very high temperatures at the location of a volcanic eruption on the Jovian moon.Featured image credit: NASA/JPL-Caltech/SwRI/INAF

“The instrument is sensitive to infrared wavelengths, which are perfect to study the volcanism of Io,” said Alberto Adriani, a member of the Juno mission team and a researcher at the National Institute of Astrophysics in Italy.

“This is one of the best images of Io that JIRAM has been able to collect so far.”

Last but not least, Juno pointed its SRU camera at Io while the moon was still covered in darkness — and snapped a glorious photo of the Jovian moon illuminated by the neighboring Europa. The light coming from this second Galilean moon served as a cosmic flashlight, bringing Io into focus.

The SRU photo, taken at 12:40 p.m. UTC, shows several interesting features, including a penetrating radiation signature, the glow of activity from several of Io’s volcanos, and a volcanic plume. The plume is circled in the image below.

SRU photo acquired by Juno at 12:40 p.m. UTC on December 21, 2018.Featured image credit: NASA/JPL-Caltech/SwRI

“As a low-light camera designed to track the stars, the SRU can only observe Io under very dimly lit conditions. December 21 gave us a unique opportunity to observe Io’s volcanic activity with the SRU using only Europa’s moonlight as our lightbulb,” said Heidi Becker, lead of Juno’s Radiation Monitoring Investigation, at NASA’s Jet Propulsion Laboratory.

Juno’s multi-spectral campaign at Io lasted for more than an hour and provided an excellent opportunity for the space probe to scrutinize the volcanic moon with a total of four scientific instruments — the three aforementioned cameras and the Ultraviolet Imaging Spectrograph (UVS). The spacecraft is fitted with eight data-gathering instruments, and orbits Jupiter once every 53 days, studying the gas giant’s auroras, atmosphere, and magnetosphere.