Evidence of water ice clouds found outside solar system

Credit: A. Fujii

A team of scientists led by Carnegie's Jacqueline Faherty has discovered the first evidence of water ice clouds on an object outside of our own Solar System.

Water ice clouds exist on our own gas giant planets, Jupiter, Saturn, Uranus, and Neptune, but have not been seen outside of the planets orbiting our Sun until now.

Their findings are published by The Astrophysical Journal Letters.

At the Las Campanas Observatory in Chile, Faherty, along with a team including Carnegie's Andrew Monson, used the FourStar near infrared camera to detect the coldest brown dwarf ever characterised.

Their findings are the result of 151 images taken over three nights and combined.

The object, named WISE J085510.83-071442.5, or W0855, was first seen by NASA's Wide-Field Infrared Explorer mission and published earlier this year. But it was not known if it could be detected by Earth-based facilities.

"This was a battle at the telescope to get the detection," said Faherty.

Chris Tinney, an Astronomer at the Australian Centre for Astrobiology, UNSW Australia and co-author on the result stated: "This is a great result. This object is so faint and it's exciting to be the first people to detect it with a telescope on the ground."

Brown dwarfs aren't quite very small stars, but they aren't quite giant planets either.

They are too small to sustain the hydrogen fusion process that fuels stars.

Their temperatures can range from nearly as hot as a star to as cool as a planet, and their masses also range between star-like and giant planet-like.

They are of particular interest to scientists because they offer clues to star-formation processes. They also overlap with the temperatures of planets, but are much easier to study since they are commonly found in isolation.


A team of scientists led by Carnegie's Jacqueline Faherty has discovered the first evidence of water ice clouds on an object outside of our own Solar System. 

Water ice clouds exist on our own gas giant planets, Jupiter, Saturn, Uranus, and Neptune, but have not been seen outside of the planets orbiting our Sun until now.

Their findings are published by The Astrophysical Journal Letters. 

Credit: Produced and directed by Brian Patrick Abbott. Written by Jacqueline K. Faherty

W0855 is the fourth-closest system to our own Sun, practically a next-door neighbour in astronomical distances.

A comparison of the team's near-infrared images of W0855 with models for predicting the atmospheric content of brown dwarfs showed evidence of frozen clouds of sulphide and water.

"Ice clouds are predicted to be very important in the atmospheres of planets beyond our Solar System, but they've never been observed outside of it before now," Faherty said.

Evidence of forming planet discovered 335 light years from Earth

This graphic is an artist’s conception of the young massive star HD100546 and its surrounding disk. 

Credit: P. Marenfeld & NOAO/AURA/NSF

An international team of scientists led by a Clemson University astrophysicist has discovered new evidence that planets are forming around a star about 335 light years from Earth.

The team found carbon monoxide emission that strongly suggests a planet is orbiting a relatively young star known as HD100546. The candidate planet is the second that astronomers have discovered orbiting the star.

Theories of how planets form are well-developed. But if the new study's findings are confirmed, the activity around HD100546 would mark one of the first times astronomers have been able to directly observe planet formation happening.

New discoveries from the star could allow astronomers to test their theories and learn more about the formation of solar systems, including our own, said Sean Brittain, an associate professor of astronomy and astrophysics at Clemson.

"This system is very close to Earth relative to other disk systems," he said. "We're able to study it at a level of detail that you can't do with more distant stars. This is the first system where we've been able to do this.

"Once we really understand what's going on, the tools that we are developing can then be applied to a larger number of systems that are more distant and harder to see."

For more than a decade, the team has focused some of Earth's most powerful telescopes on a disk-shaped cloud of gas and dust that surrounds HD100546.

The star is about 2.5 times larger and 30 times brighter than the sun, Brittain said. It's in the constellation Musca, or The Fly, and can only be seen from the Southern Hemisphere.

Brittain made three trips to Chile as far back as 2003 to gather data for the research. He used telescopes at the Gemini Observatory and the European Southern Observatory.

The new planet astronomers believe they have found what would be an uninhabitable gas giant at least three times the size of Jupiter, Brittain said. Its distance from the star would be about the same distance that Saturn is from the sun.

The team used a technique called "spectro-astrometry," which enables small changes in the position of the carbon monoxide emission to be measured.

A source of excess carbon monoxide emission was detected that appears to vary in position and velocity. The varying position and velocity are consistent with orbital motion around the star.

More information: Astrophysical Journal paper - dx.doi.org/10.1088/0004-637X/791/2/136, Preprint on Arxiv: arxiv.org/abs/1409.0804

Astrophysical Journal Letters paper - iopscience.iop.org/2041-8205/766/1/L1/ , Preprint on Arxiv: arxiv.org/abs/1302.7122

Evidence of 'oceans worth' of water in Earth's mantle detected

Schematic cross section of the Earth’s interior highlighting the transition zone layer (light blue, 410-660 km depth), which has an anomalously high water storage capacity. 

The study by Schmandt and Jacobsen used seismic waves to detect magma generated near the top of the lower mantle at about 700 km depth.

Dehydration melting at those conditions, also observed in the study’s high-pressure experiments, suggests the transition zone may be nearly saturated with H2O dissolved in high-pressure rock. 

Credit: Steve Jacobsen/Northwestern University

Researchers have found evidence of a potential "ocean's worth" of water deep beneath the United States.

Although not present in a familiar form, the building blocks of water are bound up in rock located deep in the Earth's mantle, and in quantities large enough to represent the largest water reservoir on the planet, according to the research.

For many years, scientists have attempted to establish exactly how much water may be cycling between the Earth's surface and interior reservoirs through the action of plate tectonics.

Northwestern University geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt have found deep pockets of magma around 400 miles beneath North America, a strong indicator of the presence of H₂O stored in the crystal structure of high-pressure minerals at these depths.

"The total H₂O content of the planet has long been among the most poorly constrained 'geochemical parameters' in Earth science. Our study has found evidence for widespread hydration of the mantle transition zone," says Jacobsen.

For at least 20 years geologists have known from laboratory experiments that the Earth's transition zone, a rocky layer of the Earth's mantle located between the lower mantle and upper mantle, at depths between 250 and 410 miles, can, in theory, hold about 1 percent of its total weight as H₂O, bound up in minerals called wadsleyite and ringwoodite.

However, as Schmandt explains, up until now it has been difficult to figure out whether that potential water reservoir is empty, as many have suggested, or not.

If there does turn out to be a substantial amount of H₂O in the transition zone, then recent laboratory experiments conducted by Jacobsen indicate there should be large quantities of what he calls "partial melt" in areas where mantle flows downward out of the zone.

This water-rich silicate melt is molten rock that occurs at grain boundaries between solid mineral crystals and may account for about 1 percent of the volume of rocks.

"Melting occurs because hydrated rocks are carried from the transition zone, where the rocks can hold lots of H₂O, downward into the lower mantle, where the rocks cannot hold as much H₂O."

"Melting is the way to get rid of the H₂O that won't fit in the crystal structure present in the lower mantle," says Jacobsen.

He adds:
"When a rock starts to melt, whatever H₂O is bound in the rock will go into the melt right away. So the melt would have much higher H₂O concentration than the remaining solid. We're not sure how it got there."

"Maybe it's been stuck there since early in Earth's history or maybe it's constantly being recycled by plate tectonics."

Seismic Waves
Melt strongly affects the speed of seismic waves, the acoustic-like waves of energy that travel through the Earth's layers as a result of an earthquake or explosion.

This is because stiff rocks, like the silicate-rich ones present in the mantle, propagate seismic waves very quickly.

According to Schmandt, if just a little melt, even 1 percent or less, is added between the crystal grains of such a rock it causes it to become less stiff, meaning that elastic waves propagate more slowly.

"We were able to analyse seismic waves from earthquakes to look for melt in the mantle just beneath the transition zone," says Schmandt.

Brandon Schmandt (University of New Mexico, left) and Steve Jacobsen (Northwestern University, right) combined seismic observations from the US-Array with laboratory experiments to detect dehydration melting of hydrous mantle material beneath North America at depths of 700-800 km. 

Credit: University of New Mexico/Northwestern University

"What we found beneath the U.S. is consistent with partial melt being present in areas of downward flow out of the transition zone."

"Without the presence of H₂O, it is very difficult to explain melting at these depths. This is a good hint that the transition zone H₂O reservoir is not empty, and even if it's only partially filled that could correspond to about the same mass of H₂O as in Earth's oceans," he adds.

Jacobsen and Schmandt hope that their findings, published in the June issue of the journal Science, will help other scientists to understand how the Earth formed and what its current composition and inner workings are, as well as establish how much water is trapped in mantle rock.

"I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades," says Jacobsen

Schematic representation of seismometers placed in the US-Array between 2004 and 2014 and used in the study by Schmandt and Jacobsen to detect dehydration melting at the top of the lower mantle beneath North America. 

Credit: NSF-Earthscope

Crystals of laboratory-grown hydrous ringwoodite, a high-pressure polymorph of olivine that is stable from about 520-660 km depth in the Earth’s mantle. 

The ringwoodite pictured here contains around one weight percent of H2O, similar to what was inferred in the seismic observations made by Schmandt and Jacobsen. 

Credit: Steve Jacobsen/Northwestern University

NASA MARS MRO HiRise: Further Evidence of Dry Ice Gullies

Credit: NASA/JPL/University of Arizona.

Repeated high-resolution observations made by NASA's Mars Reconnaissance Orbiter (MRO) indicate the gullies on Mars' surface are primarily formed by the seasonal freezing of carbon dioxide, not liquid water.

The first reports of formative gullies on Mars in 2000 generated excitement and NASA Spacecraft Observes Further Evidence of Dry Ice Gullies on Mars because they suggested the presence of liquid water on the Red Planet, the eroding action of which forms gullies here on Earth.

Mars has water vapour and plenty of frozen water, but the presence of liquid water on the neighbouring planet, a necessity for all known life, has not been confirmed.

This latest report about gullies has been posted online by the journal Icarus.

"As recently as five years ago, I thought the gullies on Mars indicated activity of liquid water," said lead author Colin Dundas of the U.S. Geological Survey's (USGS) Astrogeology Science Center in Flagstaff, Arizona.

"We were able to get many more observations, and as we started to see more activity and pin down the timing of gully formation and change, we saw that the activity occurs in winter."

Dundas and collaborators used the High Resolution Imaging Science Experiment (HiRISE) camera on MRO to examine gullies at 356 sites on Mars, beginning in 2006.

Thirty-eight of the sites showed active gully formation, such as new channel segments and increased deposits at the downhill end of some gullies.

Using dated before-and-after images, researchers determined the timing of this activity coincided with seasonal carbon-dioxide frost and temperatures that would not have allowed for liquid water.

Frozen carbon dioxide, commonly called dry ice, does not exist naturally on Earth, but is plentiful on Mars.

It has been linked to active processes on Mars such as carbon dioxide gas geysers and lines on sand dunes plowed by blocks of dry ice.

One mechanism by which carbon-dioxide frost might drive gully flows is by gas that is sublimating from the frost providing lubrication for dry material to flow.

Another may be slides due to the accumulating weight of seasonal frost buildup on steep slopes.

The findings in this latest report suggest all of the fresh-appearing gullies seen on Mars can be attributed to processes currently underway, whereas earlier hypotheses suggested they formed thousands to millions of years ago when climate conditions were possibly conducive to liquid water on Mars.

"Much of the information we have about gully formation, and other active processes, comes from the longevity of MRO and other orbiters," said Serina Diniega, co-author of the paper.

"This allows us to make repeated observations of sites to examine surface changes over time."

More Information: Long-term monitoring of martian gully formation and evolution with MRO/HiRISE: DOI: 10.1016/j.icarus.2014.05.013

NASA Mars Curiosity Rover discovers evidence that water once flowed on Mars

Curiosity is finding evidence that water once flowed on Mars, an indication that life could have once existed on the planet. 

Credit: NASA Jet Propulsion Laboratory

After traveling 354 million miles and surviving a nail-biting descent to the surface of Mars, the Curiosity rover is finding that the Red Planet was once a lot like the Blue Planet.

Curiosity's exploration of Mars' barren landscape is revealing signs that water once flowed freely and that life could have existed on the planet.

"Our findings are showing that Mars is a planet that was once a whole lot like Earth," said UC Davis geology professor Dawn Sumner, co-investigator for NASA's Mars Science Laboratory team, which is exploring whether the planet ever had an environment capable of supporting microbial life.

Liquid water disappeared from Mars' surface millions of years ago, leaving behind tantalizing clues about the planet's ancient past—clues that Sumner has been deciphering since the rover landed in August 2012.

Sumner is working from Curiosity mission control at NASA's Jet Propulsion Laboratory in Pasadena while on sabbatical from UC Davis.

She helped choose which parts of the planet Curiosity should investigate. And she helps lead the team that analyzes the rocks and other geologic elements that the rover encounters.

"All the rocks we've seen on this mission are sediments that have been deposited by water," Sumner said. "We've found almost no sandstone deposited by wind."

BICEP2 Post Big Bang Discovery: Evidence spotted for universe's early expansion

In this 2007 photo provided by Steffen Richter, the sun sets behind the BICEP2 telescope, foreground, and the South Pole Telescope in Antarctica. 

In the faint glowing remains of the Big Bang, scientists found "smoking gun" evidence that the universe began with a split-second of astonishingly rapid growth from a seed far smaller than an atom. 

To find a pattern of polarization in the faint light left over from the Big Bang, astronomers scanned about 2 percent of the sky for three years with the BICEP2 at the south pole, chosen for its very dry air to aid in the observations, said the leader of the collaboration, John Kovac of Harvard. 

Credit: AP Photo/Steffen Richter

The universe was born almost 14 billion years ago, exploding into existence in an event called the Big Bang.

Now researchers say they've spotted evidence that a split-second later, the expansion of the cosmos began with a powerful jump-start.

Experts called the discovery a major advance if confirmed by others. Although many scientists already believed that initial, extremely rapid growth spurt happened, finding this evidence has been a key goal in the study of the universe.

Researchers reported Monday that they did it by peering into the faint light that remains from the Big Bang.

Lawrence Krauss

If verified, the discovery "gives us a window on the universe at the very beginning," when it was far less than one-trillionth of a second old, said theoretical physicist Lawrence Krauss of Arizona State University, who was not involved in the work.

"It's just amazing," he said. "You can see back to the beginning of time."

Alan Guth

Another outside expert, physicist Alan Guth of the Massachusetts Institute of Technology (MIT), said the finding already suggests that some ideas about the rapid expansion of the universe can be ruled out.

Right after the Big Bang, the universe was a hot soup of particles.

It took about 380,000 years to cool enough that the particles could form atoms, then stars and galaxies.

Billions of years later, planets formed from gas and dust that were orbiting stars. The universe has continued to spread out.

This image provided by the BICEP2 Collaboration shows slight temperature fluctuations, indicated by variations in colour, of the Cosmic Microwave Background (CMB) of a small patch of sky and the orientation of its polarisation, shown as short black lines.

Researchers say since the CMB is a form of light, it exhibits all the properties of light, including polarisation. 

The changes in a particular type of polarisation, indicated here, are theorised to be caused by gravitational waves. 

These waves are signals of an extremely rapid inflation of the universe in its first moments. 

Credit: AP Photo/BICEP2 Collaboration

Krauss said he thinks the new finding could rank with the greatest discoveries about the universe over the last 25 years, such as the Nobel prize-winning discovery that the universe's expansion is accelerating.

The new results were announced by a collaboration that includes researchers from the Harvard-Smithsonian Center for Astrophysics (CfA), the University of Minnesota, Stanford University, the California Institute of Technology (CalTech) and NASA's Jet Propulsion Laboratory.

The team plans to submit its results to a scientific journal this week, said its leader, John Kovac of Harvard.

Read the full article here

Massive neutrinos solve a cosmological conundrum

UK Scientists have solved a major problem with the current standard model of cosmology identified by combining results from the Planck spacecraft and measurements of gravitational lensing in order to deduce the mass of ghostly sub-atomic particles called neutrinos.

The UK team, from the universities of Manchester and Nottingham, used observations of the Big Bang and the curvature of space-time to accurately measure the mass of these elementary particles for the first time.

Planck spacecraft

The recent Planck spacecraft observations of the Cosmic Microwave Background (CMB) - the fading glow of the Big Bang - highlighted a discrepancy between these cosmological results and the predictions from other types of observations.

The CMB is the oldest light in the Universe, and its study has allowed scientists to accurately measure cosmological parameters, such as the amount of matter in the Universe and its age.

But an inconsistency arises when large-scale structures of the Universe, such as the distribution of galaxies, are observed.

Professor Richard Battye, from the University of Manchester's School of Physics and Astronomy, said: "We observe fewer galaxy clusters than we would expect from the Planck results and there is a weaker signal from gravitational lensing of galaxies than the CMB would suggest.

"A possible way of resolving this discrepancy is for neutrinos to have mass. The effect of these massive neutrinos would be to suppress the growth of dense structures that lead to the formation of clusters of galaxies."

Cosmic Microwave Background (CMB)

Neutrinos interact very weakly with matter and so are extremely hard to study.

They were originally thought to be massless but particle physics experiments have shown that neutrinos do indeed have mass and that there are several types, known as flavours by particle physicists.

The sum of the masses of these different types has previously been suggested to lie above 0.06 eV (much less than a billionth of the mass of a proton).

Adam Moss

In this paper, Professor Battye and co-author Dr Adam Moss, from the University of Nottingham, have combined the data from Planck with gravitational lensing observations in which images of galaxies are warped by the curvature of space-time.

They conclude that the current discrepancies can be resolved if massive neutrinos are included in the standard cosmological model.

They estimate that the sum of masses of neutrinos is 0.320 +/- 0.081 eV (assuming active neutrinos with three flavours).

Dr Moss said: "If this result is borne out by further analysis, it not only adds significantly to our understanding of the sub-atomic world studied by particle physicists, but it would also be an important extension to the standard model of cosmology which has been developed over the last decade."

More Information: 'Evidence for Massive Neutrinos from Cosmic Microwave Background and Lensing Observations' DOI:10.1103/PhysRevLett.112.051303

Scientific evidence reveals extent space missions damage human immune systems

Russian Cosmonaut Yelena Serova. 

Some speculate that space trips involve the development of "heat shock" proteins, which cling to Toll path receptors and cut down the immune system' detectors for finding pathogens. 

The end result is a small reaction to a possibly huge pathogen risk.

Evidence is coming to light just how much space missions take a toll on humans' immune systems.

At least 29 cases of infectious diseases being contracted on board a spacecraft were reported on during a 2012 study that looked into 106 flights and 742 crew members.

Head colds, fungal infections, and gastroenteritis were just some of the ailments that overtook the participants of the study.

What may be worse is the fact that they are million miles away from home and do not get to have sufficient bed-rest or comfort foods while under the weather.

It could be noted as quite an oddity, that space illness does not get the hype that it most likely deserves.

"The immune system can go on the fritz in space: wounds heal more slowly; infection-fighting T-cells send signals less efficiently; bone marrow replenishes itself less effectively; killer cells- another key immune system player-fight less energetically," states a 2012 Nasa article in Time.

In space, pathogens enjoy an easy time growing strong and creating a resistance wall to antimicrobials.

Specifically, herpes and staph have been reported as thriving in gravity-free environments of a spacecraft that are in extremely sterile conditions.

One particular study, which was released this week, checked out the space-born Drosophila flies.

Specimens of this type are often examined because of how close in comparison the flies' immune system is to that of humans.

It was discovered that in the instance of fungal infections microgravity wiped out the immune's response.

The researchers also studied the centrifuge-induced hypergravity, discovering that the flies' immune responses to fungi heighten as gravity increases way beyond the normal range.

On a lighter note, the immune response in the space flies to bacteria was mentioned as being "robust".

Induced gravity through the use of centrifuge seems to be the best bet at solving immune system errors, an idea thought of as resourceful for keeping on top of bone and muscle mass.

Increasing astronauts' immunity would be a plus for their experience on space missions.

It also raises the question regarding the health of Space Tourists.

Read more about Space medicines and threats to astronauts' health 

Chandra confirm evidence of jet in Milky Way's black hole

Composite image of Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way. 

Credit: X-ray: NASA /CXC /UCLA /Z. Li et al; Radio: NRAO /VLA

Astronomers have long sought strong evidence that Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is producing a jet of high-energy particles. 

Finally they have found it, in new results from NASA's Chandra X-ray Observatory and the National Science Foundation's Very Large Array (VLA) radio telescope.

Previous studies, using a variety of telescopes, suggested there was a jet, but these reports—including the orientation of the suspected jets—often contradicted each other and were not considered definitive.

"For decades astronomers have looked for a jet associated with the Milky Way's black hole. Our new observations make the strongest case yet for such a jet," said Zhiyuan Li of Nanjing University in China, lead author of a study appearing in an upcoming edition of the Astrophysical Journal and available online now.

Jets of high-energy particles are found throughout the universe, on large and small scales. They are produced by young stars and by black holes a thousand times larger than the Milky Way's black hole.

They play important roles in transporting energy away from the central object and, on a galactic scale, in regulating the rate of formation of new stars.

"We were very eager to find a jet from Sgr A* because it tells us the direction of the black hole's spin axis.

This gives us important clues about the growth history of the black hole," said Mark Morris of the University of California at Los Angeles, a co-author of the study.

The study shows the spin axis of Sgr A* is pointing in one direction, parallel to the rotation axis of the Milky Way, which indicates to astronomers that gas and dust have migrated steadily into Sgr A* over the past 10 billion years.

If the Milky Way had collided with large galaxies in the recent past and their central black holes had merged with Sgr A*, the jet could point in any direction.

The jet appears to be running into gas near Sgr A*, producing X-rays detected by Chandra and radio emission observed by the VLA.

The two key pieces of evidence for the jet are a straight line of X-ray emitting gas that points toward Sgr A* and a shock front—similar to a sonic boom—seen in radio data, where the jet appears to be striking the gas.

Additionally, the energy signature, or spectrum, in X-rays of Sgr A* resembles that of jets coming from supermassive black holes in other galaxies.

Scientists think jets are produced when some material falling toward the black hole is redirected outward. Since Sgr A* is presently known to be consuming very little material, it is not surprising that the jet appears weak.

A jet in the opposite direction is not seen, possibly because of gas or dust blocking the line of sight from Earth or a lack of material to fuel the jet.

The region around Sgr A* is faint, which means the black hole has been quiet in the past few hundred years.

However, a separate Chandra study announced last month shows that it was at least a million times brighter before then.

"We know this giant black hole has been much more active at consuming material in the past. When it stirs again, the jet may brighten dramatically," said co-author Frederick K. Baganoff of the Massachusetts Institute of Technology in Cambridge, Mass.

More information: "Evidence for a Parsec-scale Jet from the Galactic Center Black Hole: Interaction with Local Gas," Zhiyuan Li, Mark R. Morris, and Frederick K. Baganoff. xxx.lanl.gov/abs/1310.0146

NASA MRO Image: Strong evidence of Granite on Mars

NASA's Mars Reconnaissance Orbiter (MRO) is providing new spectral "windows" into the diversity of Martian surface materials. 

Here in a volcanic caldera, bright magenta outcrops have a distinctive feldspar-rich composition. 

Credit: NASA/JPL/JHUAPL/MSSS

Researchers now have stronger evidence of granite on Mars and a new theory for how the granite – an igneous rock common on Earth—could have formed there, according to a new study.

The findings suggest a much more geologically complex Mars than previously believed.

Large amounts of a mineral found in granite, known as feldspar, were found in an ancient Martian volcano.

Further, minerals that are common in basalts that are rich in iron and magnesium, ubiquitous on Mars, are nearly completely absent at this location.

The location of the feldspar also provides an explanation for how granite could have formed on Mars.

Granite, or its eruptive equivalent, rhyolite, is often found on Earth in tectonically active regions such as subduction zones.

This is unlikely on Mars, but the research team concluded that prolonged magmatic activity on Mars can also produce these compositions on large scales.

"We're providing the most compelling evidence to date that Mars has granitic rocks," said James Wray, an assistant professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology and the study's lead author.

The research was published November 17 in the Advance Online Publication of the journal Nature Geoscience. The work was supported by the NASA Mars Data Analysis Program.

More information: J Wray, et al. "Prolonged magmatic activity on Mars inferred from the detection of felsic rocks." Nature Geoscience, 2013. http://dx.doi.org/DOI: 10.1038/NGEO1994.

Russian researchers find more evidence that lightning is caused by cosmic rays

Russian physicists Alex Gurevich and Anatoly Karashtin claim, in a paper published in the journal Physical Review Letters, they have found more evidence to support their idea that lightning is caused by cosmic rays.

The notion was first proposed by Gurevich back in 1992, and has been a source of debate ever since.

No one really knows what causes lightning to form and strike—the prevailing view is that it comes about as a result of collisions between ice crystals in clouds and hail stones. But because clouds and the lightning they produce are unpredictable and hard to pin down, no one has been able to prove this theory.

Another theory, proposed by Gurevich twenty years ago, says that lightning is formed from the collisions between cosmic rays and water droplets present in thunderclouds. Now he and a colleague claim to have found evidence to support this idea.

Gurevich suggests that cosmic rays entering thunder clouds cause the air in them to be ionized, resulting in a lot of free electrons floating around. The electronic field already present in the cloud, he continues, leads to the free electrons being boosted to higher energies.

When the electrons present in the air collide with water atoms, more electrons are released, setting off what he describes as an avalanche of high-energy particles that eventually give way to a "runaway breakdown"—a discharge that is witnessed as a lightning strike.

As with other theories regarding the origins of lightning, Gurevich's ideas haven't been proved. But he hasn't been sitting still.

In this new effort, he along with Karashtin have been measuring and analyzing radio waves in storm clouds as lightning occurs. The idea is that if such strikes are due to interactions with cosmic rays, there should be measurable amounts of radio waves given off.

Gurevich and Karashtin set up equipment to monitor storm clouds over Russia and Kazakhstan—recording radio waves emitted during 3,800 lightning strikes. In analyzing the data, they found that hundreds, and perhaps even thousands of short radio wave pulses occurred just as a bolt of lightning was about to form.

Perhaps more importantly, they matched the models Gurevich had built years before. There was on hitch however, the amount of energy delivered by the cosmic rays in the model don't happen often enough in the real world to cause lightning strikes in most every thunderstorm.

Gurevich and Karashtin say the discrepancy can be explained by the addition of energy into the system by free electrons passing near hydrometeors (bits of hail or water droplets).

When that happens, very small discharges result, adding to the total charge. Taken together they say, enough energy is added to cause the cascade that leads to lightning formation.

More information: Runaway Breakdown and Hydrometeors in Lightning Initiation, Phys. Rev. Lett. 110, 185005 (2013). prl.aps.org/abstract/PRL/v110/i18/e185005

Scientists: Evidence for Speed of Gravity

Scientists have found evidence supporting the hypothesis that gravity travels at the speed of light based on data gleaned from observing Earth tides.

Scientists have been trying to measure the speed of gravity for years through experiments and observations, but few have found valid methods.

By conducting six observations of total and annular solar eclipses, as well as Earth tides, a team headed by Tang Keyun, a researcher with the Institute of Geology and Geophysics under the CAS, found that the Newtonian Earth tide formula includes a factor related to the propagation of gravity.

"Earth tide" refers to a small change in the Earth's surface caused by the gravity of the moon and sun.

Based on the data, the team, with the participation of the China Earthquake Administration (CEA) and the University of the CAS (UCAS), found that gravitational force released from the sun and gravitational force recorded at ground stations on Earth did not travel at the same speed, with the time difference exactly the same as the time it takes for light to travel from the sun to observation stations on Earth.

The scientists admitted that the observation stations are located near oceans, indicating that the influence of ocean tides might have been strong enough to interfere with the results.

Consequently, the team conducted separate observations of Earth tides from two stations in Free Tibet and China's Xinjiang, two inland regions that are far away from all four oceans, as well as took measures to filter out other potential disturbances.

By applying the new data to the propagation equation of gravity, the team found that the speed of gravity is about 0.93 to 1.05 times the speed of light with a relative error of about 5 percent, providing the first set of strong evidence showing that gravity travels at the speed of light.

Their findings have been published online in English by German science and technology publishing group Springer.

NASA LRO Finds Further Evidence of Water On The Moon

Scientists from NASA and Boston University have found small patches of ice in the Shackleton Crater, at the south pole of the Moon.

Five to 10 percent of the crater wall is made of ice, they said, after analyzing data obtained from the Mini-RF radar on Nasa's Lunar Reconnaissance Orbiter.

"These terrific results from the Mini-RF team contribute to the evolving story of water on the moon. Several of the instruments on LRO have made unique contributions to this story, but only the radar penetrates beneath the surface to look for signatures of blocky ice deposits," said John Keller, a scientist at NASA's Goddard Space Flight Center.

Scientists believe that because the interior of the Shackleton crater lies in permanent shadow it is cold enough for ice to accumulate.

"Inside the crater, we don't see evidence for glaciers like on earth. Glacial ice has a whopping radar signal, and these measurements reveal a much weaker signal consistent with rugged terrain and limited ice," said Bradley Thomson, researcher at Boston University.

DNA Evidence Can be Fabricated: Proof

Scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of what has been considered the gold standard of proof in criminal cases.

The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person.

“You can just engineer a crime scene,” said Dan Frumkin, lead author of the paper, which has been published online by the journal Forensic Science International: Genetics. “Any biology undergraduate could perform this.”

Dr. Frumkin is a founder of Nucleix, a company based in Tel Aviv that has developed a test to distinguish real DNA samples from fake ones that it hopes to sell to forensics laboratories.

The planting of fabricated DNA evidence at a crime scene is only one implication of the findings. A potential invasion of personal privacy is another.

Using some of the same techniques, it may be possible to scavenge anyone’s DNA from a discarded drinking cup or cigarette butt and turn it into a saliva sample that could be submitted to a genetic testing company that measures ancestry or the risk of getting various diseases.

Celebrities might have to fear “genetic paparazzi,” said Gail H. Javitt of the Genetics and Public Policy Center at Johns Hopkins University.

Tania Simoncelli, science adviser to the American Civil Liberties Union, said the findings were worrisome.