Io Archives

September 13, 2013December 23, 2015 by Elizabeth Howell

10 Historic Moments in Voyager’s Journey to Interstellar Space

The Voyager spacecraft have been on an extensive mission of discovery that has lasted some 36 years. Image Credit: NASA/JPL

Yesterday, NASA announced that as of August 2012, Voyager 1 is in a new frontier to humanity: interstellar space. Our most distant spacecraft is now in a region where the plasma (really hot gas) environment comes more from between the stars than from the sun itself. (There’s still debate as to whether it’s in or out of the solar system, as this article explains.)

The plucky spacecraft is close to 12 billion miles (19 million kilometers) from home, and in its 36 years of voyaging has taught us a lot about the planets, their moons and other parts of space. Here are 10 of some of its most historic moments. Did we miss any? Let us know in the comments.

10. The launch: Aug. 20, 1977

Voyager 1 launches from the Kennedy Space Center on Sept. 5, 1977. Credit: NASA

Voyager 1 blasted off from Cape Canaveral on Sept. 5, 1977. Its twin, Voyager 2, departed Earth 16 days earlier. Each spacecraft carried various scientific instruments on board as well as a “Golden Record” that had sounds of Earth on it, as well as a diagram showing where Earth is in the universe.

9. Capturing the Earth and Moon together for the first time

On Sept. 18, 1977, Voyager 1 took three images of the Earth and Moon that were combined into this one image. The moon is artificially brightened to make it show up better. Credit: NASA

About two weeks after launching, Voyager 1 turned back towards Earth and took three images, which were combined into this single view of the Earth and Moon together in space. This was the first time both bodies were pictured together, NASA said.

8. The ‘Pale Blue Dot’ image

Voyager 1 pale blue dot. Image credit: NASA/JPL

On February 14, 1990, Voyager 1 was about 3.7 billion miles (6 billion kilometers) away from Earth. Scientists commanded the spacecraft to turn its face towards the solar system and snap some pictures of the planets. Among them was this famous image of Earth, which astronomer Carl Sagan called the Pale Blue Dot. “Look again at that dot. That’s here. That’s home. That’s us,” wrote Sagan in his 1997 book of the same name. In 2013, the spacecraft Cassini also took a picture of Earth, and NASA encouraged everyone to wave back.

7. Finding moons “shepherding” Saturn’s F ring

Prometheus, a small potato-shaped moon of Saturn, shown in this Voyager 1 picture interacting with the planet's F ring. Credit: NASA/JPL/SSI — Prometheus, a small potato-shaped moon of Saturn, shown in this Voyager 1 picture interacting with the planet’s F ring. Credit: NASA/JPL/SSI

Voyager 1 spotted Prometheus and Pandora, two moons of Saturn that keep the F ring separate from the rest of the debris, as well as Atlas, which “shepherds” the A ring. More recently, astronomers have found even more interesting things in Saturn’s rings — such as rain.

6. Spotting what appeared to be a LOT of water ice on Saturn’s moons

Encaladus, a moon of Saturn, as shown in this Voyager 1 image. Credit: NASA

After many years of seeing Saturn’s moons as mere points of light, Voyager 1 buzzed several of them in its quick flyby through the system: Dione, Enceladus, Mimas, Rhea, Tethys and Titan among them. Many of these moons appeared to be icy, which was a surprising find since astronomers previously thought water was pretty rare in the Solar System. We know better now.

5. Imaging Titan’s orange haze

Saturn's moon Titan lies under a thick blanket of orange haze in this Voyager 1 picture. Credit: NASA — Saturn’s moon Titan lies under a thick blanket of orange haze in this Voyager 1 picture. Credit: NASA

Voyager 1 pictures such as this tortured astronomers for decades — what lies beneath this mysterious haze surrounding Titan, Saturn’s moon? That mystery, in fact, inspired the European Space Agency to send a lander to the moon, called Huygens, which successfully reached the surface in 2005.

4. Finding active volcanoes on Io

Io's blotchy volcanoes are clearly visible in this image from Voyager 1. Credit: NASA — Io’s blotchy volcanoes are clearly visible in this image from Voyager 1. Credit: NASA

Voyager 1 helped show us that the Solar System is full of very interesting moons. At Io — a moon of Jupiter — it turns out the moon flexes during its 42-hour orbit of massive Jupiter, which powers a lot of volcanic activity.

3. Voyager 1 becomes the most distant human object

A 2013 snapshot riding along with Voyager 1's looking back at the Sun and inner solar system. The positions of Voyager 2 and Pioneers 10 and 11 show within the viewport as well. — A 2013 computer-generated snapshot riding along with Voyager 1’s looking back at the Sun and inner solar system. The positions of Voyager 2 and Pioneers 10 and 11 show within the viewport as well.

On Feb. 17, 1998, Voyager 1’s distance surpassed that of another long-flying probe, Pioneer 10. This made Voyager 1 the farthest-flung human object in space.

2. Riding the “magnetic highway”

Artist concept of NASA’s Voyager 1 spacecraft exploring a new region in our solar system called the “magnetic highway.” Credit: NASA/JPL-Caltech

In December, NASA said Voyager 1 had reached an area (as of July 28, 2012) where high-energy magnetic particles were starting to bleed through the bubble of lower-energy particles from our sun. “Voyager’s discovered a new region of the heliosphere that we had not realized was there. It’s a magnetic highway where the magnetic field of the Sun is connected to the outside. So it’s like a highway, letting particles in and out,” said project scientist Ed Stone at the time. After that point, as more measurements were analyzed by different teams, there was a lot of debate as to whether Voyager had reached interstellar space.

1. Reaching interstellar space

This graphic shows the main evidence that Voyager 1 has reached interstellar space. The blue line shows particle density, which dropped as Voyager 1 moved away from the sun, and then jumped again after it crossed the "termination shock" that is where the sun's solar wind (particles streaming from the sun) slows down. Credit: NASA/JPL-Caltech — This graphic shows the main evidence that Voyager 1 has reached interstellar space. The blue line shows particle density, which dropped as Voyager 1 moved away from the sun, and then jumped again after it crossed the “termination shock” that is where the sun’s solar wind (particles streaming from the sun) slows down. Credit: NASA/JPL-Caltech

With Voyager 1 now known to be in interstellar space, we’re lucky enough to have a few years left to communicate with it before it runs out of power. All of the instruments will be turned off by 2025, and then engineering data will be available for about 10 years beyond that. The silent emissary from humanity will then come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear) called AC+79 3888 in the year 40,272 AD and then orbit the center of the Milky Way for millions of years.

August 23, 2013December 23, 2015 by Nancy Atkinson

Major Volcanic Eruption Seen on Jupiter’s Moon Io

Voyager 1 acquired this image of Io on March 4, 1971. An enormous volcanic explosion can be seen silhouetted against dark space over Io's bright limb. Credit: NASA/JPL.

Recent observations of Jupiter’s moon Io has revealed a massive volcanic eruption taking place 628,300,000 km (390,400,000 miles) from Earth. Io, the innermost of the four largest moons around Jupiter, is the most volcanically active object in the Solar System with about 240 active regions. But this new one definitely caught the eye of Dr. Imke de Pater, Professor of Astronomy and of Earth and Planetary Science at the University of California in Berkeley. She was using the Keck II telescope on Mauna Kea in Hawaii on August 15, 2013 when it immediately became apparent something big was happening at Io.

“When you are right at the telescope and see the data, this is something you can see immediately, especially with a big eruption like that,” de Pater told Universe Today via phone.

de Pater said this eruption is one of the top 10 most powerful eruptions that have been seen on this moon. “It is a very energetic eruption that covers over a 30 square kilometer area,” she said. “For Earth, that is big, and for Io it is very big too. It really is one of the biggest eruptions we have seen.”

She added the new volcano appears to have a large energy output. “We saw a big eruption in 2001, which was in the Surt region, which is well known as the biggest one anyone has ever seen,” she said. “For this one, the total energy is less but per square meter, it is bigger than the one in 2001, so it is very powerful.”

While Io’s eruptions can’t be seen directly from Earth,infrared cameras on the Keck telescope (looking between 1 and 5 microns) have been able to ascertain there are likely fountains of lava gushing from fissures in the Rarog Patera region of Io, aptly named for a Czech fire deity.

While many regions of Io are volcanically active, de Pater said she’s not been able to find any other previous activity that has been reported in the Rarog Patera area, which the team finds very interesting.

Ashley Davies of NASA’s Jet Propulsion Laboratory in Pasadena, California and a member of the observing team told Universe Today that Rarog Patera was identified as a small, relatively innocuous hot spot previously in Galileo PPR data and possibly from Earth, but at a level way, way below what was seen on August 15, and reported in New Scientist.

de Pater and other astronomers will be taking more data soon with Keck and perhaps more telescopes to try and find out more about this massive eruption.

“We never know about eruptions – they can last hours, days months or years, so we have no idea how long it will stay active,” she said, “but we are very excited about it.”

No data or imagery has been released on the new eruption yet since the team is still making their observations and will be writing a paper on this topic.

Scientists think a gravitational tug-of-war with Jupiter is one cause of Io’s intense vulcanism.

May 21, 2013December 23, 2015 by Elizabeth Howell

Mystery of Escaping Planetary Atmospheres Comes Under Japanese Scrutiny

Artist's conception of the solar system, often used in the Eyes on the Solar System 3D Simulator. Credit: NASA

Venus and Mars may be all right tonight, but there’s still a lot we don’t understand about these planets. Why does one, Venus, have such a thick atmosphere? Why is that of Mars so thin? And why is Earth’s atmosphere so different again from what we see on Venus and Mars?

A new JAXA (Japan Aerospace Exploration Agency) satellite aims to better understand what’s going on. It’s called SPRINT-A, for Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere.

JAXA has set an official launch date of Aug. 22 from the Uchinoura Space Center, although the window extends as far as Sept. 30. (Launches can be delayed due to weather and mechanical difficulties.) The satellite’s expected Earth orbit will range from 590 to 715 miles (950 to 1150 kilometers) above the planet.

“Venus and Earth may be called twin planets, and it recently becomes clear that three terrestrial planets in the solar system – including Mars – have very similar environments in the beginning era of the solar system,” JAXA stated in a press release.

Earth may not have formed quite like once thought (Image: NASA/Suomi NPP) — Earth’s atmosphere was similar to that of Venus and Mars in the early solar system, but now it’s quite different, says JAXA. (Image: NASA/Suomi NPP)

The agency pointed out, however, that these three planets ended up with different fates. Venus has a runaway greenhouse effect on its planet, with surface temperatures reaching a scorching 752 degrees Fahrenheit (400 degrees Celsius). Mars, on the other hand, has a very thin atmosphere and more variable temperatures that can get a little chilly.

Understanding how atmospheres escape into outer space is the main goal of SPRINT-A. The sun, the scientists stated, had more intense activity in the past than what we see presently, which could have blown away the atmosphere on some terrestrial planets.

“The study on interaction of the strong solar wind on the atmosphere of the planet leads to acquiring knowledge of history in the early stage of the solar system,” JAXA stated.

Besides looking at the inner solar system, SPRINT-A will investigate a phenomenon related to a splotchy volcanic moon orbiting the planet Jupiter.

Io, a moon of Jupiter. The colors in this image have been enhanced to better show differences. Sulfur dioxide frost appears in white and grey, and other types of sulfur are in yellow and brown. Recent volcanic activity is marked by red and black blotches. Credit: NASA

SPRINT-A aims to better understand a ring of material surrounding Jupiter that came from Io.

Electrons and ions from the volcanic moon surround Jupiter and, as they collide, produce ultraviolet light in a process similar to what causes auroras in the upper atmosphere of Earth and other planets. How this happens is still being figured out, though.

It’s a pretty radiation-heavy environment in that region of the solar system. The spacecraft Galileo safely orbited the Jovian moons for years, but humans would have a little more trouble surviving the radiation without heavy shielding and careful precautions.

Check out more information about SPRINT-A on JAXA’s website. Japan also recently announced it will launch the Kounotori 4 cargo spacecraft to the International Space Station in August, likely Aug. 4.

April 4, 2013December 23, 2015 by Nancy Atkinson

Io’s Volcanoes are in the Wrong Place

This five-frame sequence of images from NASA's New Horizons mission captures the giant plume from Io's Tvashtar volcano in March, 2007. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Jupiter’s moon Io features at least 400 active volcanoes, making it the most volcanically active world in our Solar System. However, the location of the volcanoes on Io just doesn’t match up with scientific models that predict how the moon’s interior is heated.

“Rigorous statistical analysis of the distribution of volcanoes in the new global geologic map of Io,” said Christopher Hamilton of the University of Maryland, College Park and the Goddard Spaceflight Center. “We found a systematic eastward offset between observed and predicted volcano locations that can’t be reconciled with any existing solid body tidal heating models.”

Io’s internal heat is created by the tidal forces inflicted from the giant planet Jupiter on one side and from two neighboring moons that orbit further from Jupiter – Europa and Ganymede on the other.

Researchers say there are questions about how this tidal heating affects the moon’s interior. Some propose it heats up the deep interior, but the prevailing view is that most of the heating occurs within a relatively shallow layer under the crust, called the asthenosphere. The asthenosphere is where rock behaves like putty, slowly deforming under heat and pressure.

“Our analysis supports the prevailing view that most of the heat is generated in the asthenosphere, but we found that volcanic activity is located 30 to 60 degrees East from where we expect it to be,” said Hamilton.

On Earth, a simple explanation how volcanoes are created is that when tectonic plates shift in such a way, the subsurface magma is able to flow onto the surface. On Io, the tidal forces from Jupiter actually force Io’s surface to bulge up and down by as much as 100 m, causing magma to flow continuously.

The scientists explained the tug-of-war between Jupiter’s massive gravity and the smaller but precisely timed pulls from two neighboring moons like this:

Io orbits faster than these other moons, completing two orbits every time Europa finishes one, and four orbits for each one Ganymede makes. This regular timing means that Io feels the strongest gravitational pull from its neighboring moons in the same orbital location, which distorts Io’s orbit into an oval shape. This in turn causes Io to flex as it moves around Jupiter.

For example, as Io gets closer to Jupiter, the giant planet’s powerful gravity deforms the moon toward it and then, as Io moves farther away, the gravitational pull decreases and the moon relaxes. The flexing from gravity causes tidal heating — in the same way that you can heat up a spot on a wire coat hanger by repeatedly bending it, the flexing creates friction in Io’s interior, which generates the tremendous heat that powers the moon’s extreme volcanism.

This is a map of the predicted heat flow at the surface of Io from different tidal heating models. Red areas are where more heat is expected at the surface while blue areas are where less heat is expected. Figure A shows the expected distribution of heat on Io's surface if tidal heating occurred primarily within the deep mantle, and figure B is the surface heat flow pattern expected if heating occurs primarily within the asthenosphere. In the deep mantle scenario, surface heat flow concentrates primarily at the poles, whereas in the asthenospheric heating scenario, surface heat flow concentrates near the equator. Credit: NASA/Christopher Hamilton. — This is a map of the predicted heat flow at the surface of Io from different tidal heating models. Red areas are where more heat is expected at the surface while blue areas are where less heat is expected. Figure A shows the expected distribution of heat on Io’s surface if tidal heating occurred primarily within the deep mantle, and figure B is the surface heat flow pattern expected if heating occurs primarily within the asthenosphere. In the deep mantle scenario, surface heat flow concentrates primarily at the poles, whereas in the asthenospheric heating scenario, surface heat flow concentrates near the equator. Credit: NASA/Christopher Hamilton.

But a new geologic map of Io showed the offset of the volcanoes from where the model predicted them to be.

Possibilities to explain the offset include a faster than expected rotation for Io, an interior structure that permits magma to travel significant distances from where the most heating occurs to the points where it is able erupt on the surface, or a missing component in existing tidal heating models, like fluid tides from an underground magma ocean, according to the team.

The magnetometer instrument on NASA’s Galileo mission detected a magnetic field around Io, suggesting the presence of a global subsurface magma ocean. As Io orbits Jupiter, it moves inside the planet’s vast magnetic field. Researchers think this could induce a magnetic field in Io if it had a global ocean of electrically conducting magma.

“Our analysis supports a global subsurface magma ocean scenario as one possible explanation for the offset between predicted and observed volcano locations on Io,” says Hamilton. “However, Io’s magma ocean would not be like the oceans on Earth. Instead of being a completely fluid layer, Io’s magma ocean would probably be more like a sponge with at least 20 percent silicate melt within a matrix of slowly deformable rock.”

Tidal heating is also thought to be responsible for oceans of liquid water likely to exist beneath the icy crusts of Europa and Saturn’s moon Enceladus. Since liquid water is a necessary ingredient for life, some researchers propose that life might exist in these subsurface seas if a useable energy source and a supply of raw materials are present as well. These worlds are far too cold to support liquid water on their surfaces, so a better understanding of how tidal heating works may reveal how it could sustain life in otherwise inhospitable places throughout the Universe.

“The unexpected eastward offset of the volcano locations is a clue that something is missing in our understanding of Io,” says Hamilton. “In a way, that’s our most important result. Our understanding of tidal heat production and its relationship to surface volcanism is incomplete. The interpretation for why we have the offset and other statistical patterns we observed is open, but I think we’ve enabled a lot of new questions, which is good.”

Io’s volcanism is so extensive that it gets completely resurfaced about once every million years or so, actually quite fast compared to the 4.5-billion-year age of the solar system. So in order to know more about Io’s past, we have to understand its interior structure better, because its surface is too young to record its full history, according to Hamilton.

Source: JPL

March 20, 2012December 23, 2015 by Nancy Atkinson

First Ever Geologic Map of Io: 425 Volcanoes, No Craters

A map of hotspots and mountians on Io, just one of the features of the first geologic map of Io. Credit: ASU

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With billowing volcanoes, lava lakes and a sulfurous landscape, Jupiter’s moon Io is one of the most exotic and intriguing places in the Solar System. The geologic features of Io are now detailed in the first global geologic map ever made of this unusual and active planetary body. The map, published by the U. S. Geological Survey and created by scientists from the Planetary Science Institute and Arizona State University, shows the characteristics and relative ages of some of the most geologically unique and active volcanoes and lava flows ever documented in the Solar System.

Want to figure out where you’d like to go mountain climbing or conduct a little volcanology on Io?

“One of the reasons for making this map was to create a tool for continuing scientific studies of Io, and a tool for target planning of Io observations on future missions to the Jupiter system,” said David Williams, who led the six-year research project to produce the geologic map.

On this detailed map there are 19 different surface material types. You can see all sorts of volcanic features including: paterae (caldera-like depressions), lava flow fields, tholi (volcanic domes), and plume deposits, in various shapes, sizes and colors, as well as high mountains and large expanses of sulfur- and sulfur dioxide-rich plains. The mapping identified 425 paterae, or individual volcanic centers.

“Our mapping has determined that most of the active hot spots occur in paterae, which cover less than 3 percent of Io’s surface. Lava flow fields cover approximately 28 percent of the surface, but contain only 31 percent of hot spots,” said Williams. “Understanding the geographical distribution of these features and hot spots, as identified through this map, are enabling better models of Io’s interior processes to be developed.”

However, there is one feature you won’t see on the geologic map: impact craters.

“Io has no impact craters; it is the only object in the Solar System where we have not seen any impact craters, testifying to Io’s very active volcanic resurfacing,” says Williams.

Although Io is so volcanically active — more than 25 times more volcanically active than Earth — most of the long-term surface changes resulting from volcanism are restricted to less than 15 percent of the surface, mostly in the form of changes in lava flow fields or within paterae.

Interestingly, the new map comes from fairly old – but enhanced – data. It combines the best images from the Voyager 1 and 2 missions (acquired in 1979) as well as the Galileo orbiter (1995-2003), and is unique from other USGS-published planetary geologic maps because surface features were mapped and characterized from using four distinct global image mosaics.

“Because of the non-uniform coverage of Io by multiple Voyager and Galileo flybys, including a variety of lighting conditions, it was absolutely necessary to use the different mosaics to identify specific geologic features, such as separating mountains and paterae from plains, and separating the colored plume deposits from the underlying geologic units,” Williams said.

Though the geology history of Io has been studied in detail for several decades, completion of the geologic map establishes a critical framework for integrating and comparing diverse studies.

Because of Io’s active nature, this map may not be completely accurate to Io’s current appearance. “Because Io is so active, and continues to be studied by Earth-based telescopes, we are doing something different than producing just the paper geologic map,” says Williams. “We are also making an online Io database, to include the geologic map, the USGS mosaics, and all useful Galileo spacecraft observations of Io. This database, when completed later this year, will allow users to track the history of surface changes due to volcanic activity. We also have proposals submitted to NASA to include in our Io database Earth-based telescopic observations and images from the February 2007 NASA New Horizons spacecraft flyby, to create a single online source to study the history of Io volcanism.”

The geologic map can be downloaded from the USGS here.

Source: ASU

December 23, 2011December 24, 2015 by Nancy Atkinson

Podcast: Io

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If you want to see one of the strangest places in the Solar System, look no further than Io, Jupiter’s inner Galilean moon. The immense tidal forces from Jupiter keep the moon hotter than hot, with huge volcanoes blasting lava hundreds of kilometers into space.

Click here to download the episode.
Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

“Io” shownotes on the Astronomy Cast website.

May 12, 2011December 24, 2015 by Nancy Atkinson

Magma Ocean Flows Beneath Io’s Surface

This graphic shows the internal structure of Jupiter's moon Io as revealed by data from NASA's Galileo spacecraft. The low-density crust about 30 to 50 kilometers (20 to 30 miles) thick is shown in gray in the cross-section. Image credit: NASA/JPL/University of Michigan/UCLA

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Proving that old data never dies, scientists have found something new about Jupiter’s moon Io using data gathered during the Galileo mission, which orbited Jupiter from 1995-2003. New analysis reveals a subsurface ocean of molten or partially molten magma beneath the surface of the volcanic moon, which is the first direct confirmation of this kind of magma layer at Io. Scientists say the molten subsurface ocean explains why the moon is the most volcanic object known in the solar system.

“Scientists are excited we finally understand where Io’s magma is coming from and have an explanation for some of the mysterious signatures we saw in some of the Galileo’s magnetic field data,” said Krishan Khurana, from the University of California, Los Angeles, and lead author of the study published in Science. Khurana was a former co-investigator on Galileo’s magnetometer team at UCLA. “It turns out Io was continually giving off a ‘sounding signal’ in Jupiter’s rotating magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface.”

Amazingly, Io produces about 100 times more lava each year than all the volcanoes on Earth, and the new study shows that a global magma ocean exists about 30 to 50 kilometers (20 to 30 miles) beneath the moon’s crust. This explains why Io’s volcanoes are distributed all around its surface, unlike Earth’s volcanoes that occur in localized hotspots like the “Ring of Fire” around the Pacific Ocean.

The volcanoes on Io were discovered in 1979 by Linda Morabito, an optical navigation engineer working on the Voyager mission. Looking at images that were to be used for navigating Voyager, Morabito noted what appeared to be a crescent cloud extending beyond the edge of Io. After conferring with her colleagues, they realized that since Io has no atmosphere, the cloud rising hundreds of kilometers above the surface must be evidence of an incredibly powerful volcano.

The energy for the volcanic activity comes from the squeezing and stretching of the moon by Jupiter’s gravity as Io orbits the largest planet in the solar system.

Galileo was launched in 1989 and began orbiting Jupiter in 1995. Scientists noticed unexplained signatures in magnetic field data from Galileo flybys of Io in October 1999 and February 2000.

“During the final phase of the Galileo mission, models of the interaction between Io and Jupiter’s immense magnetic field, which bathes the moon in charged particles, were not yet sophisticated enough for us to understand what was going on in Io’s interior,” said Xianzhe Jia, a co-author of the study at the University of Michigan.

Recent work in mineral physics showed that a group of rocks known as “ultramafic” rocks become capable of carrying substantial electrical current when melted. Ultramafic rocks are igneous in origin, or form through the cooling of magma. On Earth, they are believed to originate from the mantle. The finding led Khurana and colleagues to test the hypothesis that the strange signature was produced by current flowing in a molten or partially molten layer of this kind of rock.

Tests showed that the signatures detected by Galileo were consistent with a rock such as lherzolite, an igneous rock rich in silicates of magnesium and iron found in Spitzbergen, Norway. The magma ocean layer on Io appears to be more than 50 kilometers (30 miles thick), making up at least 10 percent of the moon’s mantle by volume. The blistering temperature of the magma ocean probably exceeds 1,200 degrees Celsius (2,200 degrees Fahrenheit).

In the animation above, Io is bathed in magnetic field lines (shown in blue) that connect the north polar region of Jupiter to the planet’s south polar region. As Jupiter rotates, the magnetic field lines draping around Io strengthen and weaken. Because Io’s magma ocean has a high electrical conductivity, it deflects the varying magnetic field, shielding the inside of the moon from magnetic disturbances. The magnetic field inside of Io maintains a vertical orientation, even as the magnetic field outside of Io dances around. These variations in the external magnetic field signatures enabled scientists to understand the moon’s internal structure. In the animation, the magnetic field lines move with Jupiter’s rotation period of about 13 hours in Io’s rest frame.

Io is the only body in the solar system other than Earth known to have active magma volcanoes, and it has been suggested both the Earth and its moon may have had similar magma oceans billions of years ago at the time of their formation, but they have long since cooled.

“Io’s volcanism informs us how volcanoes work and provides a window in time to styles of volcanic activity that may have occurred on the Earth and moon during their earliest history,” said Torrence Johnson, a former Galileo project scientist who was not directly involved in the study.

The Galileo spacecraft was intentionally sent into Jupiter’s atmosphere in 2003 to avoid any contamination of any of Jupiter’s moons.

Source: JPL