Juno Solves 39-Year Old Mystery Of Jupiter Lightning







“Jupiter lightning distribution is inside out relative to Earth,” said Brown. “There is a lot of activity near Jupiter’s poles but none near the equator. You can ask anybody who lives in the tropics—this doesn’t hold true for our planet.”







NASA’s Juno spacecraft will make its 13th science flyby over Jupiter’s mysterious cloud tops on July 16.

NASA Finds Ancient Organic Material, Mysterious Methane On Mars








Seasonal Methane Releases




Finding Organic Molecules









As Solar Wind Blows, Our Heliosphere Balloons

What happens when the solar wind suddenly starts to blow significantly harder? According to two recent studies, the boundaries of our entire solar system balloon outward—and an analysis of particles rebounding off of its edges will reveal its new shape.

In late 2014, NASA spacecraft detected a substantial change in the solar wind. For the first time in nearly a decade, the solar wind pressure—a combined measure of its speed and density—had increased by approximately 50 percent and remained that way for several years thereafter. Two years later, the Interstellar Boundary Explorer, or IBEX, spacecraft detected the first sign of the aftermath. Solar wind particles from the 2014 pressure increase had reached the edge of the heliosphere, neutralized themselves, and shot all the way back to Earth. And they had a story to tell.

In two recent articles, scientists used IBEX data along with sophisticated numerical models to understand what these rebounding atoms can tell us about the evolving shape and structure of our heliosphere, the giant bubble carved out by the solar wind.

“The results show that the 2014 solar wind pressure increase has already propagated from the Sun to the outer heliosphere, morphing and expanding our heliosphere’s boundaries in their closest direction,” said David McComas, the principal investigator for the IBEX mission at Princeton University in Princeton, New Jersey. “IBEX data pouring in over the next few years will let us chart the expansion and evolving structure of the other portions of the heliosphere’s outer boundaries.”

From the Sun to the edge of the solar system—and backAt the crux of the story are energetic neutral atoms—high-energy particles produced at the very edge of our solar system.

As the solar wind flows out from the Sun at supersonic speeds, it blows up a bubble known as the heliosphere. The heliosphere encases all the planets in our solar system and much of the space beyond them, separating the domain of our Sun from that of interstellar space.

But the solar wind’s journey from the Sun is not a smooth ride. On its way to the very edge of our heliosphere, known as the heliopause, the solar wind passes through distinct layers. The first of these is known as the termination shock.

Before passing the termination shock, the solar wind expands rapidly, largely unimpeded by outside material.

“But at the termination shock, roughly 9.3 billion miles away from us in every direction, the solar wind slows down abruptly. Beyond this point it continues to move outwards, but it is much hotter,” said Eric Zirnstein, lead author of one of the papers at Princeton.

Once beyond the termination shock, solar wind particles enter a special limbo zone known as the heliosheath. While the termination shock is essentially spherical, the edges of the heliosphere are thought to describe more of an arc around the Sun as it moves through space—closer to the Sun toward the front, and extending long behind it, not unlike a comet with a tail. Along these boundaries, solar wind particles mix with particles from interstellar space. Collisions are inevitable: the hot, electrically-charged solar wind particles bang into the slower, colder neutral atoms from interstellar space, stealing an electron and becoming neutral themselves.

“From there they go travelling ballistically through space, and some make it all the way back to Earth,” Zirnstein said. “These are the energetic neutral atoms that IBEX observes.”

In late 2016, when IBEX’s energetic neutral atom imager began to pick up an unusually strong signal, Professor McComas and his team set out to investigate its cause. Their findings are reported in an article published on March 20, 2018, in the Astrophysical Journal Letters.

The energetic neutral atoms were coming from about 30 degrees south of the interstellar upwind direction, where the heliosheath was known to be closest to Earth.

To quantify its connection to the 2014 solar wind pressure increase, McComas and his team turned to numerical simulations, working out how such a pressure increase could affect the energetic neutral atoms that IBEX observes.

“These types of simulations involve a model for the physics, which then gets turned into equations, which are in turn solved on a supercomputer,” said Jacob Heerikhuisen, a coauthor on both papers at the University of Alabama in Huntsville.

Using computer models, the team simulated an entire heliosphere, jolted it with a solar wind pressure increase, and let it run the numbers. The simulation completed a story only hinted at by the data.

According to the simulation, once the solar wind hits the termination shock it creates a pressure wave. That pressure wave continues on to the edge of the heliosphere and partially rebounds backwards, forcing particles to collide within the (now much denser) heliosheath environment that it just passed through. That’s where the energetic neutral atoms that IBEX observed were born.

The simulations provided a compelling case: IBEX was indeed observing the results of the 2014 solar wind pressure increase, more than two years later.

But the simulation didn’t stop there. It also revealed that the 2014 solar wind pressure increase would, over time, continue to blow up the heliosphere even further. Three years after the solar wind pressure increase—by the time the article was published—the termination shock, the inner bubble within the heliosphere, should expand by seven astronomical units, or seven times the distance from Earth to the Sun. The heliopause, the outer bubble, should expand by two astronomical units, with an additional two the following year.

In short, by cranking up the pressure of the solar wind, our heliosphere today is bigger than it was just a few years ago.

The heliosphere’s new shape

McComas and colleagues studied the very first signs of the 2014 solar wind pressure increase. But watching the data over the coming years may tell us even more—this time about the evolving shape of our heliosphere.

“There have been many studies, some from quite a while ago, predicting what the heliosphere shape should look like,” Zirnstein, the lead author of the paper, reports. “But it’s still very much up for debate in the modelling community. We’re hoping that the 2014 solar wind pressure increase could help with that.”

Using the same data and simulations used in the previous paper, Zirnstein and colleagues ran the clock forward, modeling the heliosphere eight years after the 2014 solar wind pressure increase. The results describe not only the past, but also model the future. The paper was published on May 30, 2018, in The Astrophysical Journal.

“What we think we should see in the near future is a ring, expanding across the sky, marking the change in energetic neutral atom flux over time,” said Zirnstein. “This ring expands away from the point of initial contact in the outer heliosphere, towards the directions of the heliotail.”

Although the initial signal detected by IBEX in 2016 was a solid circle, it won’t stay that way. As the 2014 solar wind reaches points of the heliopause further and further away, they take longer to bounce back, like an echo off of a far-away wall. The heliosphere’s rounded shape causes this echo to reflect back in the form of a ring.

But the key finding came from watching the ring as it expands.

In their simulation, Zirnstein and colleagues found that the precise rate at which the ring expands depended in part on the distances between the various layers of the heliosphere: the termination shock, the heliopause, and the part of the heliosheath where the energetic neutrals were produced. Zirnstein realized he had found a new way to measure the size and shape of the heliosphere.

“We could estimate the distances to the different boundaries of the heliosphere just by looking at this ring changing over time in the sky,” said Zirnstein.

Zirnstein and colleagues used their simulated heliosphere to run a test study. By measuring the rate of expansion of the ring (and plugging it into the right equations), they could accurately reproduce the distances to key structures within their simulated heliosphere. Since they knew what those distances were in their simulation, they could check their work—validating that the technique got the right answers and should be accurate when applied to the real heliosphere.

Deformities in the ring—deviations from a perfect circle—could also reveal asymmetries in the heliosphere’s overall shape. “It depends on how symmetric or asymmetric the heliosphere is,” Zirnstein added. “If the heliosphere was an ideal ‘comet shape,’ the ring should expand symmetrically over time. But in reality that’s probably not going to happen—we’ll have to wait and see what IBEX tell us.”

Zirnstein expressed excitement about the possibility of learning the true shape of the heliosphere.

“Over the next few years with more IBEX data, my hope is that we can build a 3-D picture of the shape of the heliosphere,” said Zirnstein.

The results of these two studies have important practical implications. “Connecting changes in the Sun with energetic neutral atom observations will help us understand long term changes in the hazardous conditions for space radiation environment—a sort of space climate as opposed to space weather,” McComas said. “As the solar wind blows more and less hard, and our solar bubble expands and contracts, which directly affects the amount of cosmic rays that can enter the heliosphere, potentially endangering astronauts on long duration spaceflights.”

But the results also underscore the incredible power of our closest star. Changes on the Sun, including the solar wind, have significant consequences extending billions of miles into space where, to date, only the two Voyager spacecraft have ever ventured. With techniques like energetic neutral atom imaging, we cannot just picture, but precisely measure these far-off portions of the heliosphere—our home in the galaxy.

How Do You Weigh A Galaxy? Especially The One You’re In?

Pinning down the mass of a galaxy may seem like an esoteric undertaking, but scientists think it holds the key to unraveling the nature of the elusive, yet-to-be-seen dark matter, and the fabric of our cosmos.


Determining the mass of galaxies plays a crucial part in unraveling fundamental mysteries about the architecture of the universe. According to current cosmological models, a galaxy’s visible matter, such as stars, gas and dust, accounts for a mere 15 percent of its mass. The remaining 85 percent is believed to reside in dark matter, a mysterious component that never has been observed and whose physical properties remain largely unknown. The vast majority of a galaxy’s mass (mostly dark matter) is located in its halo, a vast, surrounding region containing few, if any, stars and whose shape is largely unknown.

In a widely accepted cosmological model, dark-matter filaments span the entire universe, drawing luminous (“regular”) matter with them. Where they intersect, gas and dust accumulate and coalesce into galaxies. Over billions of years, small galaxies merge to form into larger ones, and as those grow in size and their gravitational pull reaches farther and farther into space, they attract a zoo of other small galaxies, which then become satellite galaxies. Their orbits are determined by their host galaxy, much like the sun’s gravitational pull directs the movement of planets and bodies in the solar system.

“We now know that the universe is expanding,” says Patel, a fourth-year graduate student in the UA’s Department of Astronomy and Steward Observatory. “But when two galaxies come close enough, their mutual attraction is greater than the influence of the expanding universe, so they begin to orbit each other around a common center, like our Milky Way and our closest neighbor, the Andromeda Galaxy.”

Although Andromeda is approaching the Milky Way at 110 kilometers per second, the two won’t merge until about 4.5 billion years from now. According to Patel, tracking Andromeda’s motion is “equivalent to watching a human hair grow at the distance of the moon.”

Because it’s impossible to “weigh” a galaxy simply by looking at it — much less when the observer happens to be inside of it, as is the case with our Milky Way — researchers deduce a galaxy’s mass by studying the motions of celestial objects as they dance around the host galaxy, led by its gravitational pull. Such objects — also called tracers, because they trace the mass of their host galaxy — can be satellite galaxies or streams of stars created from the scattering of former galaxies that came too close to remain intact.

Unlike previous methods commonly used to estimate a galaxy’s mass, such as measuring its tracers’ velocities and positions, the approach developed by Patel and her co-authors uses their angular momentum, which yields more reliable results because it doesn’t change over time. The angular momentum of a body in space depends on both its distance and speed. Since satellite galaxies tend to move around the Milky Way in elliptical orbits, their speeds increase as they get closer to our galaxy and decrease as they get farther away. Because the angular momentum is the product of both position and speed, there is no net change regardless of whether the tracer is at its closest or farthest position in its orbit.

“Think of a figure skater doing a pirouette,” Patel says. “As she draws in her arms, she spins faster. In other words, her velocity changes, but her angular momentum stays the same over the whole duration of her act.”

The study, which Patel presents on Thursday, June 7, at the 232nd meeting of the of the American Astronomical Society in Denver, is the first to look at the full three-dimensional motions of nine of the Milky Way’s 50 known satellite galaxies at once and compare their angular momentum measurements to a simulated universe containing a total of 20,000 host galaxies that resemble our own galaxy. Together those simulated galaxies host about 90,000 satellite galaxies.

Patel’s team pinned down the Milky Way’s mass at 0.96 trillion solar masses. Previous estimates had placed our galaxy’s mass between 700 billion and 2 trillion solar masses. The results also reinforce estimates suggesting that the Andromeda Galaxy (M31) is more massive than our Milky Way.


“Our method allows us to take advantage of measurements of the speed of multiple satellite galaxies simultaneously to get an answer for what cold dark matter theory would predict for the mass of the Milky Way’s halo in a robust way,” Besla says. “It is perfectly suited to take advantage of the current rapid growth in both observational datasets and numerical capabilities.”

Thank The Moon For Earth’s Lengthening Day

A new study that reconstructs the deep history of our planet’s relationship to the moon shows that 1.4 billion years ago, a day on Earth lasted just over 18 hours. This is at least in part because the moon was closer and changed the way Earth spun around its axis.

“As the moon moves away, the Earth is like a spinning figure skater who slows down as they stretch their arms out,” explains Stephen Meyers, professor of geoscience at the University of Wisconsin-Madison and co-author of the study published this week [June 4, 2018] in the Proceedings of the National Academy of Sciences.

It describes a tool, a statistical method, that links astronomical theory with geological observation (called astrochronology) to look back on Earth’s geologic past, reconstruct the history of the solar system and understand ancient climate change as captured in the rock record.

“One of our ambitions was to use astrochronology to tell time in the most distant past, to develop very ancient geological time scales,” Meyers says. “We want to be able to study rocks that are billions of years old in a way that is comparable to how we study modern geologic processes.”

Earth’s movement in space is influenced by the other astronomical bodies that exert force on it, like other planets and the moon. This helps determine variations in Earth’s rotation around and wobble on its axis, and in the orbit Earth traces around the sun.

These variations are collectively known as Milankovitch cycles and they determine where sunlight is distributed on Earth, which also means they determine Earth’s climate rhythms. Scientists like Meyers have observed this climate rhythm in the rock record, spanning hundreds of millions of years.

But going back further, on the scale of billions of years, has proved challenging because typical geologic means, like radioisotope dating, do not provide the precision needed to identify the cycles. It’s also complicated by lack of knowledge of the history of the moon, and by what is known as solar system chaos, a theory posed by Parisian astronomer Jacques Laskar in 1989.

The solar system has many moving parts, including the other planets orbiting the sun. Small, initial variations in these moving parts can propagate into big changes millions of years later; this is solar system chaos, and trying to account for it can be like trying to trace the butterfly effect in reverse.

Last year, Meyers and colleagues cracked the code on the chaotic solar system in a study of sediments from a 90 million-year-old rock formation that captured Earth’s climate cycles. Still, the further back in the rock record he and others have tried to go, the less reliable their conclusions.

For instance, the moon is currently moving away from Earth at a rate of 3.82 centimeters per year. Using this present day rate, scientists extrapolating back through time calculated that “beyond about 1.5 billion years ago, the moon would have been close enough that its gravitational interactions with the Earth would have ripped the moon apart,” Meyers explains. Yet, we know the moon is 4.5 billion years old.

So, Meyers sought a way to better account for just what our planetary neighbors were doing billions of years ago in order to understand the effect they had on Earth and its Milankovitch cycles. This was the problem he brought with him to a talk he gave at Columbia University’s Lamont-Doherty Earth Observatory while on sabbatical in 2016.

In the audience that day was Alberto Malinverno, Lamont Research Professor at Columbia. “I was sitting there when I said to myself, ‘I think I know how to do it! Let’s get together!'” says Malinverno, the other study co-author. “It was exciting because, in a way, you dream of this all the time; I was a solution looking for a problem.”

The two teamed up to combine a statistical method that Meyers developed in 2015 to deal with uncertainty across time — called TimeOpt — with astronomical theory, geologic data and a sophisticated statistical approach called Bayesian inversion that allows the researchers to get a better handle on the uncertainty of a study system.

They then tested the approach, which they call TimeOptMCMC, on two stratigraphic rock layers: the 1.4 billion-year-old Xiamaling Formation from Northern China and a 55 million-year-old record from Walvis Ridge, in the southern Atlantic Ocean.

With the approach, they could reliably assess from layers of rock in the geologic record variations in the direction of the axis of rotation of Earth and the shape of its orbit both in more recent time and in deep time, while also addressing uncertainty. They were also able to determine the length of day and the distance between Earth and the moon.

“In the future, we want to expand the work into different intervals of geologic time,” says Malinverno.

The study complements two other recent studies that rely on the rock record and Milankovitch cycles to better understand Earth’s history and behavior.

A research team at Lamont-Doherty used a rock formation in Arizona to confirm the remarkable regularity of Earth’s orbital fluctuations from nearly circular to more elliptical on a 405,000 year cycle. And another team in New Zealand, in collaboration with Meyers, looked at how changes in Earth’s orbit and rotation on its axis have affected cycles of evolution and extinction of marine organisms called graptoloids, going back 450 million years.

“The geologic record is an astronomical observatory for the early solar system,” says Meyers. “We are looking at its pulsing rhythm, preserved in the rock and the history of life.”

Guatemala Volcano: Dozens Die as Fuego Volcano Erupts

Guatemala’s most violent volcanic eruption in more than a century has killed at least 25 people.

Another 46 people are missing, the country’s disaster agency says. Villages on the slopes of Fuego volcano were buried in volcanic ash, mud and rocks as the volcano erupted for 16 and a half hours on Sunday.


President Jimmy Morales has declared three days of national mourning. A further pyroclastic flow on Monday sparked alarm.

The official death toll is 25 but volunteer firefighters say they have found another five bodies, according to local media.

A powerful earthquake has also hit the Guatemalan coast, though there are no reports of damage so far.

What has happened?
Fuego, about 40km (25 miles) south-west of the capital Guatemala City, spewed rock, gas and ash into the sky. Fast-moving flows hit villages, killing people inside their homes.

Sergio Cabañas, head of the country’s National Disaster Management Agency (Conred), said the town of El Rodeo had been “buried”.

Other towns affected include Alotenango and San Miguel Los Lotes. Rescuers are still trying to reach a number of villages and the death toll is expected to rise.

Temporary shelters have been set up for about 3,000 residents who have been evacuated. Efrain Gonzalez, who fled El Rodeo with his  wife and one-year-old daughter, said he had had to leave behind his two older children, aged four and ten, trapped in the family home.

Local resident Ricardo Reyes was forced to abandon his home: “The only thing we could do was run with my family and we left our possessions in the house. Now that all the danger has passed, I came to see how our house was – everything is a disaster.”

A total of about 1.7 million people have been affected in four regions. The country’s main airport has now reopened. Officials have advised people to wear masks as protection against falling ash.

How exceptional was the eruption?
Fuego is one of Latin America’s most active volcanoes. A major eruption devastated nearby farms in 1974, but no deaths were recorded.

Another eruption in February this year sent ash 1.7km (1.1 mile) into the sky. Sunday’s event was on a much greater scale.

This eruption is Guatemala’s deadliest such event since 1902, when an eruption of the Santa Maria volcano killed thousands of people.

Guatemala’s national institute of volcanology, Insivumeh, told people to keep away from the affected ravines as there is a possibility of “a reactivation”.

The institute also warned of the possibility of lahars – when water mixes with volcanic deposits forming a destructive debris flow – which could affect villages and hamlets to the south, south-west and south-east.

Hawaii’s Kilauea Volcano Eruption Enters New Phase As Crater Falls Quiet

As lava continued to pour vigorously from the ground through fissures at the foot of Kilauea Volcano, the month-old eruption on Hawaii’s Big Island has entered a new, seemingly calmer phase inside the summit crater, government scientists have said.

But vulcanologists monitoring and measuring Kilauea’s every move during the past four weeks hastened to add the latest change in the volcano’s behaviour, while undoubtedly significant, leaves them uncertain about what will follow.

The summit crater, which began ejecting ash and volcanic rock in periodic, daily eruptions in mid-May, has largely fallen quiet since Wednesday, Kyle Anderson, a US Geological Survey (USGS) geophysicist, told reporters in a conference call.

The apparent reason, newly revealed in footage recorded by drone aircraft flown over the summit, is that tons of rocky material shaken loose from the inside walls of the crater vent have plugged up the bottom of the void, Anderson said.

What happens next is unknown.

“It’s possible that new explosions will blast through the rubble at the bottom of the vent, and these may or may not be larger than previous explosions,” he said. “It’s also possible that the vent could become permanently blocked, ending the explosions entirely.”

In any case, the volcano’s behaviour ultimately hinges on the ebb and flow of huge rivers of molten rock called magma, the term for lava while it remains underground.

The steady collapse of the crater’s inner walls, caused by magma draining out of the summit and oozing downslope under the volcano’s surface, has also greatly enlarged the mouth of the vent, which has grown in size from about 12 acres (4.9 hectares) to 120 acres (48.5 hectares), Anderson said.

At the same time, the Kilauea summit itself has sunken, or subsided, by at least 5 feet (1.50 meters) in elevation as the magma level continues to drop, exerting tremendous pressure on seismic faults to create numerous earthquakes, mostly small tremors, in the immediate vicinity.

Although the summit crater of Kilauea has fallen silent for the moment, many of the two dozen volcanic fissures running through populated areas on its eastern flank continued to spout and ooze lava and toxic gases that prompted the evacuation of some 2,500 residents. At least 75 homes — most of them in the hard-hit community of Leilani Estates — have been devoured by streams of red-hot molten rock creeping across the landscape since May 3. Lava flows also have knocked out power and telephone lines in the region, disrupting communications.

Another issue has been the occurrence of a phenomenon called Pele’s hair — fine, glass-like fibres of volcanic material produced by fountains of lava and carried aloft by the wind. The filament, named for the mythical goddess of volcanoes, can cause skin, eye and respiratory irritation like fibreglass.

Residents have been warned to avoid exposure to Pele’s hair, one of several airborne volcano hazards including emissions of sulphur dioxide gas, wind-blown ash and noxious clouds of laze – a term combining the words “lava” and “haze” – formed when lava reacts with seawater to form a mix of acid fumes, steam and glass-like specks.

The latest upheaval of Kilauea, one of the world’s most active volcanoes, comes on the heels of an earlier eruption cycle that began in 1983 and continued almost nonstop for 35 years, destroying 215 dwellings and other structures.