While volcanic eruptions are next to impossible to predict, researchers have found a volcano that blows up on a relatively regular schedule — on Io, one of Jupiter’s largest moons.
Christened Loki, the volcano on Io is expected to erupt in mid-September, according to a poster by Planetary Science Institute Senior Scientist Julie Rathbun presented today at the EPSC-DPS Joint Meeting 2019 in Geneva.
“Loki is the largest and most powerful volcano on Io, so bright in the infrared that we can detect it using telescopes on the Earth,” Rathbun said.
Based on over 20 years’ worth of observations, Loki undergoes periodic brightenings as it erupts — and these brightenings follow a relatively regular schedule. One of Rathbun’s previous studies showed that this schedule was roughly once every 540 days during the 1990s; currently, it appears to be once every 475 days.
“If this behavior remains the same, Loki should erupt in September 2019, around the same time as the EPSC-DPS Joint Meeting 2019. We correctly predicted that the last eruption would occur in May of 2018,” said Rathbun.
Volcanic eruptions are difficult to predict because many different factors have to come together for them to take place. The rate of magma upwelling, its chemical composition, the presence of gas bubbles in said magma, what type of rock the volcano sits on top of, as well as how fractured or massive that rock is, all have an impact on when a volcano erupts.
What Rathbun thinks sets Loki apart is its sheer size. Because it’s so large, the effects of these individual factors, overall, are secondary to those of “basic physics” — which are much more easily-predictable.
“However, you have to be careful because Loki is named after a trickster god and the volcano has not been known to behave itself. In the early 2000s, once the 540 day pattern was detected, Loki’s behavior changed and did not exhibit periodic behavior again until about 2013,” she explains.
The paper “Io’s Loki volcano: An explanation of its tricky behavior and prediction for the next eruption” has been presented today, 17 September, at the EPSC-DPS Joint Meeting 2019 and can be read on the Meeting’s journal here.
A rocky extrasolar moon brimming with lava could orbit a planet 550 light-years from Earth, astronomers led by researchers from Bern University have discovered.
The volcanically active exomoon could be hidden in the exoplanet system WASP-49b, orbiting a hot giant planet in the inconspicuous constellation of Lepus, underneath the bright Orion constellation.
The researchers describe the exomoon as an ‘extreme’ version of Jupiter’s moon Io — the most volcanically active body in our own solar system. Thus, painting a picture of an exotic and dangerous world — an ‘exo-Io’.
Apurva Oza, a postdoctoral fellow at the Physics Insitute of the University of Bern and associate of the NCCR PlanetS, describes the exomoon, comparing it to a famous sci-fi setting: “It would be a dangerous volcanic world with a molten surface of lava — a lunar version of close-in Super-Earths like 55 Cancri-e.
“A place where Jedis go to die, perilously familiar to Anakin Skywalker.”
More than a grain of sodium. Uniting theory and circumstantial evidence.
Astronomers have yet to discover a moon beyond our solar system meaning that the researchers base their suspicions of the existence of this exo-Io on circumstantial evidence — namely sodium gas in WASP-49b at an unusually high-altitude.
Oza explains: “The neutral sodium gas is so far away from the planet that it is unlikely to be emitted solely by a planetary wind.
“The sodium is right where it should be.”
Comparing this feature to observations of the Jupiter and Io system using low-mass calculations demonstrated to the team that an exo-Io could, indeed, be a plausible mechanism for sodium at WASP-49b.
The theory that large amounts of sodium around an exoplanet could point to a hidden moon or a ring of material was advance by Bob Johnson and Patrick Huggins in 2006. Following this, researchers from the University of Virginia calculated that a three-body system comprised of a star, close giant planet and a moon could remain stable for billions of years.
Oza took these theoretical predictions to form the basis of he and his colleagues’ work — published in the Astrophysical Journal.
The astrophysicist explains: “The enormous tidal forces in such a system are the key to everything.
“The energy released by the tides to the planet and its moon keeps the moon’s orbit stable, simultaneously heating it up and making it volcanically active.”
The researchers also demonstrate in their study that a small rocky moon would eject more sodium and potassium into space via this extreme volcanism than a large gas planet. This would especially be the case at high altitudes.
These emissions can then be identified by astronomers using the technique of spectroscopy. These particular elements are particularly useful to astronomers.
Oza adds: “Sodium and potassium lines are quantum treasures to us astronomers because they are extremely bright.
“The vintage street lamps that light up our streets with yellow haze, is akin to the gas we are now detecting in the spectra of a dozen exoplanets.”
When comparing their calculations with actual observations of sodium and potassium, the team found five candidate systems where a hidden exomoon could survive thermal evaporation. In the case of WASP-49b, the best explanation for the observed data was the presence of an exo-Io.
This isn’t the only explanation, however. As mention above, the observations of sodium at high altitudes could instead indicate the exoplanet is surrounded by a ring of material — most likely ionised gas.
Oza admits that the team need to find more clues, and as such, are relying on future observations with both ground and space-based telescopes. Also, as a few of these exo-Ios could eventually be destroyed as a result of extreme mass-loss, the team also want to search for evidence of such destruction.
Oza concludes: “While the current wave of research is going towards habitability and biosignatures, our signature is a signature of destruction.
“The exciting part is that we can monitor these destructive processes in real-time, like fireworks.”
Using giant Earth-based telescopes in tandem with the movement of Jupiter’s moons, astronomers were able to peer inside a huge lava lake on Io. This is the largest lava lake in the solar system and interestingly it produces huge lava waves on its surface.
On March 8, 2015, Jupiter’s moon Europa passed in front of Io, allowing detailed mapping of the bright volcanic crater called Loki Patera (upper left). The lower right feature is a different volcanic hotspot. Credit: UC Berkeley.
Io, the innermost of the four Galilean moons of the planet Jupiter, is the most volcanically active body in the solar system which explains Loki Patera, the huge lava lake in question. At 8,300 square miles, it’s like Lake Ontario, only made of a lava instead of water. Actually, because of tidal heating, most of Io’s crust is literally lava.
A simple glance of Io is enough to understand what I mean — hundreds and hundreds of outpouring of lava dot the moon’s surface. Some are short-lived eruptions, others are stable lava lakes like Loki Patera.
“If Loki Patera is a sea of lava, it encompasses an area more than a million times that of a typical lava lake on Earth,” said Katherine de Kleer, a UC Berkeley graduate student and the study’s lead author. “In this scenario, portions of cool crust sink, exposing the incandescent magma underneath and causing a brightening in the infrared.”
Loki Patera is the horseshoe-shaped dark object in this exquisite photo of Io. Credit: NASA.
To study Loki Patera, scientists used high-end telescopes but also the help of a rare natural phenomenon. On the 8th of March, 2015, another of Jupiter’s moons — Europa — passed between Io and Earth blocking infrared radiation emanating from Loki Patera for a few moments. As Europa blocked extraneous light, researchers operating the Large Binocular Telescope were able to measure the temperature of different parts of the huge lava lake.
Previously, observations suggested that temperature on the surface of the lake fluctuated greatly, rising sharply every 500 days or so. These new observations help explain why this happens. Periodically, the very top layer of lava of the lake forms a crust, cools into a dense mass, then sinks flushing out and exposing hotter lava. Using data from the new measurements and knowing cooling rates of lava lakes found here on Earth, the team was able to not only figure out how hot the lava of Loki Patera is but also how old it is.
From infrared measurements, the researchers could deduce the age of the lava at the surface of the lake. The youngest is in the lower right, having overturned most recently, about 75 days before the observations. Credit: Katherine de Kleer.
Apparently, the lava on the lake cools in two waves. One travels counterclockwise from the north part of the lake while the other travels clockwise. These waves of activity move slowly across the lake at a rate of about a kilometer/day. As the days go by, the waves will eventually offset despite starting at roughly the same time. According to Ashley Davies, one of the study’s authors, this may be due to the fact that there are two distinct sources of magma feeding each area of the lake. Each of these sources has a different composition of gas which ultimately makes the cooled crust sink at different rates, as reported in the journal Nature.
The video below shows a simulation of the two resurfacing waves sweeping around Loki Patera at different rates.
All of this very violent volcanic behavior is exciting for a number of reasons. Though 628 million kilometers away, Io is like a window into our own planet’s past. Earth, Mars, and Venus were all previously largely shaped and modified by eruption events that went on for millions of years. Let’s just say Earth had a very tumultuous youth.
Another important consideration is that the tidal heating that’s feeding Io’s surface with so much lava are similar to the same forces at work on Ganymede and Europa, Io’s neighbors. Not too long ago, NASA unveiled evidence of hydrogen molecules in the plumes gushing out of Europa’s surface — telltale signs of hot spots hidden beneath the moon’s icy crust which could support life. Who know what we might learn next when Europa blocks Ion again in 2021.
“This is a step forward in trying to understand volcanism on Io, which we have been observing for more than 15 years, and in particular the volcanic activity at Loki Patera,” said Imke de Pater, a UC Berkeley professor of astronomy.
Io’s atmosphere just collapsed, and according to astronomical observations, this isn’t even unusual. According to a study published in the Journal of Geophysical Research, every time Jupiter eclipses Io and blocks its access to the Sun (for about two hours, every day), the surface temperature plummets and the moon’s sulfur dioxide (SO2) collapses.
Artist’s concept of Jupiter’s volcanic moon Io, whose volcanoes create an ephemeral atmosphere during sunlit hours. Image: Southwest Research Institute
Io is one of the most hellish places in the solar system. Jupiter’s moon is the most volcanically active place around the Sun, and that’s not all of it. It’s a cold, frigid place and with a toxic, sulphurous atmosphere. As if that wasn’t even enough, now we know that its atmosphere collapses every single day.
“This research is the first time scientists have observed this phenomenon directly, improving our understanding of this geologically active moon,” said Tsang, a senior research scientist in SwRI’s Space Science and Engineering Division.
The findings were presented in a paper bluntly called “The Collapse of Io’s Primary Atmosphere in Jupiter Eclipse,” in which astronomers used the eight-meter Gemini North telescope in Hawaii and the Texas Echelon Cross Echelle Spectrograph (TEXES).
What basically happens is that for about two hours every day, Jupiter passes between the Sun and Io, blocking sun waves. Without this access to the Sun, Io starts to cool, and fast. Data showed that temperatures drop from -148 degrees Celsius (-235 Fahrenheit) in sunlight to -168 degrees Celsius (-270 Fahrenheit) during eclipse. By the time this cooling fully takes place, the atmosphere is like a punctured balloon – a thin coating around the planet. But as Jupiter’s shadow fades away, the atmosphere starts to re-sublimate, and a new atmosphere develops. Every single day.
“This confirms that Io’s atmosphere is in a constant state of collapse and repair, and shows that a large fraction of the atmosphere is supported by sublimation of SO2 ice,” study co-author John Spencer said in a statement. “We’ve long suspected this, but can finally watch it happen.”
It’s interesting to note that although Io’s sulphurous atmosphere is mostly produced by volcanoes, temperature still has a critical impact.
Prior to the study, no direct observations of Io’s atmosphere in eclipse had been possible because Io’s atmosphere is difficult to observe in the darkness of Jupiter’s shadow. The breakthrough was possible due to TEXES. The spectrograph measures the atmosphere using heat radiation, not sunlight, and the giant Gemini telescope can sense the faint heat signature of Io’s collapsing atmosphere.
An ocean of magma could explain why Jupiter’s moon Io has volcanoes in the “wrong place”. This would also mean that Io has an ocean of liquid water beneath its surface and might be potentially habitable. NASA’s research also suggests that this type of tidally stressed moon might be more common than previously thought.
This five-frame sequence of images from the New Horizons spacecraft captures the giant plume from Io’s Tvashtar volcano. Credits: NASA/JHU Applied Physics Laboratory/Southwest Research Institute
“This is the first time the amount and distribution of heat produced by fluid tides in a subterranean magma ocean on Io has been studied in detail,” said Robert Tyler of the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We found that the pattern of tidal heating predicted by our fluid-tide model is able to produce the surface heat patterns that are actually observed on Io.”
Tyler is lead author of a paper on this research published June 2015 in the Astrophysical Journal Supplement Series.
The 300-kilometer (190-mile) high plume from the Tvashtar volcano is at the 11 o’clock position on Io’s disk, with a smaller plume from the volcano Prometheus at the 9 o’clock position on the edge of Io’s disk, and the volcano Amirani between them along the line dividing day and night. Credits: NASA/JHU Applied Physics Laboratory/Southwest Research Institute
Io is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons. It’s also the driest place in the solar system, and has extremely active volcanoes. This extreme geologic activity is the result of friction generated within Io’s interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto, which are much smaller, but also closer. The volcanoes are so massive that they spew out lava up to 250 miles (about 400 kilometers) high.
Previously, it was thought that this heat interacted with Io as a solid, but deformable body – much like clay. However, when scientists compared computer models using this assumption to a map of the actual volcano locations on Io, they discovered that most of the volcanoes were offset 30 to 60 degrees to the East of where the models put them – and this came as a complete surprise. The pattern was consistent throughout the entire lunar surface, which meant it was more than just a coincidence. Something more was involved.
“It’s hard to explain the regular pattern we see in so many volcanoes, all shifting in the same direction, using just our classical solid-body tidal heating models,” said Wade Henning of the University of Maryland and NASA Goddard, a co-author of the paper.
The enigma called for another explanation, one that had to do with heat transfer and fluid dynamics.
“Fluids – particularly ‘sticky’ (or viscous) fluids – can generate heat through frictional dissipation of energy as they move,” said co-author Christopher Hamilton of the University of Arizona, Tucson. The team thinks much of the ocean layer is likely a partially molten slurry or matrix with a mix of molten and solid rock. As the molten rock flows under the influence of gravity, it may swirl and rub against the surrounding solid rock, generating heat. “This process can be extremely effective for certain combinations of layer thickness and viscosity which can generate resonances that enhance heat production,” said Hamilton.
This would have implications not only for Io, but for all similar moons, in terms of extraterrestrial life. It’s already confirmed that Europa has a subsurface ocean, and this raises new possibilities for other moons.
“Long-term changes in heating or cooling rates within a subsurface ocean are likely to produce a combination of ocean layer thickness and viscosity that generates a resonance and produces considerable heat,” said Hamilton. “Therefore the mystery may be not how such subsurface oceans could survive, but how they could perish. Consequently, subsurface oceans within Io and other satellites could be even more common than what we’ve been able to observe so far.”
Scientists analyzing data from the Large Binocular Telescope Observatory in Arizona spotted a huge lava lake on Io, one of Jupiter’s largest moons.
This global view of Io was obtained by NASA’s Galileo spacecraft on 19 September 1997 at a range of more than 500,000 km (310,000 miles). In this image, deposits of sulfur dioxide frost appear in white and grey hues while yellowish and brownish hues are probably due to other sulfurous materials. Bright red materials and ‘black’ spots with low brightness mark areas of recent volcanic activity and are usually associated with high temperatures and surface changes. Image credit: NASA / JPL / University of Arizona.
We’ve known for a while that Io is quite an amazing (and hellish) place; it’s the most geologically active place in the solar system, with extreme geologic activity occurring as a result of tidal friction. As both Jupiter and the other Galilean satellites – Europa, Ganymede and Callisto – tug and pull, Io’s interior generates huge amount of friction, which in turn generate very high levels of volcanism. Several volcanoes produce plumes of sulfur and sulfur dioxide that go as high as 500 km (300 mi) above Io’s surface. The satellite is dotted with over 100 high mountains created as a result of this extreme geology, with some of the mountains taller than Mount Everest – something remarkable for a satellite 4 times smaller than Earth.
The largest of these volcanic features is called Loki, after the Norse god of fire and chaos – and a fitting name it is. The Loki Patera depression is 202 kilometres (126 mi) in diameter, which is huge for a volcanic feature, but when you consider the distance from Earth to Io, it’s almost insignificant. In fact, until recently, it couldn’t be seen from Earth. But now, thanks to the Large Binocular Telescope Interferometer (LBTI), a group of astronomers was able to see it from Earth for the first time.
“We have seen bright emissions – always one unresolved spot – ‘pop-up’ at different locations in Loki Patera over the years. New images from the LBTI show for the first time that these emissions arise simultaneously from different sites in Loki Patera,” said Prof Imke de Pater of the University of California, Berkeley.
A huge area of Io’s volcanic plains is shown in this Voyager 1 image mosaic. Numerous volcanic calderas and lava flows are visible here. Loki Patera, an active lava lake, is the large shield-shaped black feature. Image via NASA/ JPL.
Their research confirms previous theories – that there’s a massive lava lake at the Loki Patera.
“This strongly suggests that the horseshoe-shaped feature is most likely an active overturning lava lake, as hypothesized in the past.”
Team member Dr Chick Woodward from the University of Minnesota added: “studying the very dynamic volcanic activity on Io, which is constantly reshaping the moon’s surface, provides clues to the interior structure and plumbing of this moon.”
But aside from finding a massive lava lake on what should be a frozen moon, this study could have massive implications for extraterrestrial life. Io itself is not habitable, but it’s the best place in our solar system to study tidal heating and tidal volcanism – which is crucial for potential extraterrestrial life on places like Europa, Saturn’s moon. It also helps with some of NASA’s (and other space agencies) future missions.
“It helps to pave the way for future NASA missions such as the Io Observer. Io’s highly elliptical orbit close to Jupiter is constantly tidally stressing the moon, like the squeezing of a ripe orange, where the juice can escape through cracks in the peel.”
Since it was first discovered more than four hundred years ago by Galileo Galilei, Jupiter’s innermost moon Io has played an important part in the development of astronomy. Still with secrets to be revealed, a team of US scientists have recently formulated the first complete global geologic map of Jupiter’s satellite.
The moon of Io is the most geologically active object in the Solar System, as result of tidal heating from friction generated within Io’s interior as it is pulled between Jupiter and the other Galilean satellites. This intense, tremendous heat ends up getting released through Io’s surface, hence the great volcanic activity – the moon is considered to be 25 times more volcanically active than Earth.
“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,” explained David Williams of ASU.
Galileo SSI high resolution (7–8 m/pixel) images of undivided patera floor material and white plains material in Chaac Patera, with lower resolution context. (c) David A. Williams
The map was published by the US Geological Survey (USGS) with the help of Arizona State University (ASU), and depicts the characteristics and relative ages of some of the most geologically unique and active volcanoes and lava flows ever documented in the Solar System. Included in the highly detailed, color map one can study paterae (caldera-like depressions or individual volcanic centers), 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 also identified 425 paterae, or individual volcanic centers. Curiously enough, though, not one impact crater was observed on the geological map of Io.
“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.”
There are hundreds of active volcanic spots on Jupiter’s satellite, but in spite of this, either they’re all mostly concentrated together in a small surface, or the geological and geographical changes resulted from their volcanic activity is relatively limited, being restricted to less than 15 percent of the surface.
“Our mapping has determined that most of the active hot spots occur in paterae, which cover less than 3 percent of Io’s surface,” Williams noted.
“Lava flow fields cover approximately 28 percent of the surface, but contain only 31 percent of hot spots. 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.”
The complete geological map of Io is actually a mosaic, as it was mapped and characterized using four distinct global image. These image mosaics, generated by the USGS, combine the best images from NASA’s Voyager 1 and 2 missions (acquired in 1979) as well as the Galileo orbiter (1995-2003).