Sunday, September 30, 2012

NASA's Solar Fleet Peers Into Coronal Cavities

Scientists want to understand what causes giant explosions in the sun's atmosphere, the corona, such as this one. The eruptions are called coronal mass ejections or CMEs and they can travel toward Earth to disrupt human technologies in space. To better understand the forces at work, a team of researchers used NASA data to study a precursor of CMEs called coronal cavities. Credit: NASA/Solar Dynamics Observatory (SDO) 

The sun's atmosphere dances. Giant columns of solar material – made of gas so hot that many of the electrons have been scorched off the atoms, turning it into a form of magnetized matter we call plasma – leap off the sun's surface, jumping and twisting. Sometimes these prominences of solar material, shoot off, escaping completely into space, other times they fall back down under their own weight.

The prominences are sometimes also the inner structure of a larger formation, appearing from the side almost as the filament inside a large light bulb. The bright structure around and above that light bulb is called a streamer, and the inside "empty" area is called a coronal prominence cavity.

Such structures are but one of many that the roiling magnetic fields and million-degree plasma create in the sun's atmosphere, the corona, but they are an important one as they can be the starting point of what's called a coronal mass ejection, or CME. CMEs are billion-ton clouds of material from the sun’s atmosphere that erupt out into the solar system and can interfere with satellites and radio communications near Earth when they head our way.

"We don't really know what gets these CMEs going," says Terry Kucera, a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "So we want to understand their structure before they even erupt, because then we might have a better clue about why it's erupting and perhaps even get some advance warning on when they will erupt."

Kucera and her colleagues have published a paper in the Sept. 20, 2012, issue of The Astrophysical Journal on the temperatures of the coronal cavities. This is the third in a series of papers -- the first discussed cavity geometry and the second its density -- collating and analyzing as much data as possible from a cavity that appeared over the upper left horizon of the sun on Aug. 9, 2007 (below). By understanding these three aspects of the cavities, that is the shape, density and temperature, scientists can better understand the space weather that can disrupt technologies near Earth.

The faint oval hovering above the upper left limb of the sun in this picture is known as a coronal cavity. NASA’s Solar and Terrestrial Relations Observatory (STEREO) captured this image on Aug. 9, 2007. A team of scientists extensively studied this particular cavity in order to understand more about the structure and magnetic fields in the sun's atmosphere. Credit: NASA/STEREO 

The Aug. 9 cavity lay at a fortuitous angle that maximized observations of the cavity itself, as opposed to the prominence at its base or the surrounding plasma. Together the papers describe a cavity in the shape of a croissant, with a giant inner tube of looping magnetic fields -- think something like a slinky -- helping to define its shape. The cavity appears to be 30% less dense than the streamer surrounding it, and the temperatures vary greatly throughout the cavity, but on average range from 1.4 million to 1.7 million Celsius (2.5 to 3 million Fahrenheit), increasing with height.

Trying to describe a cavity, a space that appears empty from our viewpoint, from 93 million miles away is naturally a tricky business. "Our first objective was to completely pin down the morphology," says Sarah Gibson, a solar scientist at the High Altitude Observatory at the National Center for Atmospheric Research (NCAR) in Boulder, Colo. who was an author on all three cavity papers. "When you see such a crisp clean shape like this, it’s not an accident. That shape is telling you something about the physics of the magnetic fields creating it, and understanding those magnetic fields can also help us understand what’s at the heart of CMEs."

To do this, the team collected as much data from as many instruments from as many perspectives as they could, including observations from NASA’s Solar Terrestrial Relations Observatory (STEREO), ESA and NASA’s Solar and Heliospheric Observatory (SOHO), the JAXA/NASA mission Hinode, and NCAR's Mauna Loa Solar Observatory.

They collected this information for the cavity’s entire trip across the face of the sun along with the sun’s rotation. Figuring out, for example, why the cavity was visible on the left side of the sun but couldn’t be seen as well on the right held important clues about the structure’s orientation, suggesting a tunnel shape that could be viewed head on from one perspective, but was misaligned for proper viewing from the other. The cavity itself looked like a tunnel in a crescent shape, not unlike a hollow croissant. Magnetic fields loop through the croissant in giant circles to support the shape, the way a slinky might look if it were narrower on the ends and tall in the middle – the entire thing draped in a sheath of thick plasma. The paper describing this three-dimensional morphology appeared in The Astrophysical Journal on Dec. 1, 2010.

Next up, for the second paper, was the cavity’s density. Figuring out density and temperature was a trickier prospect since one’s point of view of the sun is inherently limited. Because the sun’s corona is partially transparent, it is difficult to tease out differences of density and temperature along one’s line of sight; all the radiation from a given line hits an instrument at the same time in a jumble, information from one area superimposed upon every other.

Using a variety of techniques to tease density out from temperature, the team was able to determine that the cavity was 30% less than that of the surrounding streamer. This means that there is, in fact, quite a bit of material in the cavity. It simply appears dim to our eyes when compared with the denser, brighter areas nearby. The paper on the cavity’s density appeared in The Astrophysical Journal on May 20, 2011.

"With the morphology and the density determined, we had found two of the main characteristics of the cavity, so next we focused on temperature," says Kucera. "And it turned out to be a much more complicated problem. We wanted to know if it was hotter or cooler than the surrounding material – the answer is that it is both."

Ultimately, what Kucera and her colleagues found was that the temperature of the cavity was not – on average – hotter or cooler than the surrounding plasma.

However, it was much more varied, with hotter and cooler areas that Kucera thinks link the much colder 10,000 degrees Celsius (17,000 F) prominence at the bottom to the million to two million degrees Celsius (1.8 million to 3.6 million degrees Fahrenheit) corona at the top. Other observations of cavities show that cavity features are constantly in motion creating a complicated flow pattern that the team would like to study further.

While these three science papers focused on just the one cavity from 2007, the scientists have already begun comparing this test case to other cavities and find that the characteristics are fairly consistent. More recent cavities can also be studied using the high-resolution images from NASA’s Solar Dynamics Observatory (SDO), which launched in 2010.

"Our point with all of these research projects into what might seem like side streets, is ultimately to figure out the physics of magnetic fields in the corona," says Gibson. "Sometimes these cavities can be stable for days and weeks, but then suddenly erupt into a CME. We want to understand how that happens. We’re accessing so much data, so it’s an exciting time – with all these observations, our understanding is coming together to form a consistent story."

NASA Mars Rover Targets Unusual Rock on Its Journey

The drive by NASA's Mars rover Curiosity during the mission's 43rd Martian day, or sol, (Sept. 19, 2012) ended with this rock about 8 feet (2.5 meters) in front of the rover. Image credit: NASA/JPL-Caltech 
NASA's Mars rover Curiosity has driven up to a football-size rock that will be the first for the rover's arm to examine.
Curiosity is about 8 feet (2.5 meters) from the rock. It lies about halfway from the rover's landing site, Bradbury Landing, to a location called Glenelg. In coming days, the team plans to touch the rock with a spectrometer to determine its elemental composition and use an arm-mounted camera to take close-up photographs.
Both the arm-mounted Alpha Particle X-Ray Spectrometer and the mast-mounted, laser-zapping Chemistry and Camera Instrument will be used for identifying elements in the rock. This will allow cross-checking of the two instruments.
The rock has been named "Jake Matijevic." Jacob Matijevic (mah-TEE-uh-vik) was the surface operations systems chief engineer for Mars Science Laboratory and the project's Curiosity rover. He passed away Aug. 20, at age 64. Matijevic also was a leading engineer for all of the previous NASA Mars rovers: Sojourner, Spirit and Opportunity.
Curiosity now has driven six days in a row. Daily distances range from 72 feet to 121 feet (22 meters to 37 meters).
"This robot was built to rove, and the team is really getting a good rhythm of driving day after day when that's the priority," said Mars Science Laboratory Project Manager Richard Cook of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The team plans to choose a rock in the Glenelg area for the rover's first use of its capability to analyze powder drilled from interiors of rocks. Three types of terrain intersect in the Glenelg area -- one lighter-toned and another more cratered than the terrain Curiosity currently is crossing. The light-toned area is of special interest because it retains daytime heat long into the night, suggesting an unusual composition.
"As we're getting closer to the light-toned area, we see thin, dark bands of unknown origin," said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology, Pasadena. "The smaller-scale diversity is becoming more evident as we get closer, providing more potential targets for investigation."
Researchers are using Curiosity's Mast Camera (Mastcam) to find potential targets on the ground. Recent new images from the rover's camera reveal dark streaks on rocks in the Glenelg area that have increased researchers' interest in the area. In addition to taking ground images, the camera also has been busy looking upward.
On two recent days, Curiosity pointed the Mastcam at the sun and recorded images of Mars' two moons, Phobos and Deimos, passing in front of the sun from the rover's point of view. Results of these transit observations are part of a long-term study of changes in the moons' orbits. NASA's twin Mars Exploration Rovers, Spirit and Opportunity, which arrived at Mars in 2004, also have observed solar transits by Mars' moons. Opportunity is doing so again this week.
"Phobos is in an orbit very slowly getting closer to Mars, and Deimos is in an orbit very slowly getting farther from Mars," said Curiosity's science team co-investigator Mark Lemmon of Texas A&M University, College Station. "These observations help us reduce uncertainty in calculations of the changes."
In Curiosity's observations of Phobos this week, the time when the edge of the moon began overlapping the disc of the sun was predictable to within a few seconds. Uncertainty in timing is because Mars' interior structure isn't fully understood.
Phobos causes small changes to the shape of Mars in the same way Earth's moon raises tides. The changes to Mars' shape depend on the Martian interior which, in turn, cause Phobos' orbit to decay. Timing the orbital change more precisely provides information about Mars' interior structure.
During Curiosity's two-year prime mission, researchers will use the rover's 10 science instruments to assess whether the selected field site inside Gale Crater ever has offered environmental conditions favorable for microbial life. 
                       View the original article here 

Friday, September 28, 2012

Dark energy camera snaps first images ahead of survey

Dark energy camera snaps first images ahead of survey
T he camera comprises 62 separate CCDs, the same  kind of detector familiar from consumer cameras

 The camera comprises 62 separate CCDs, the same
 kind of detector familiar from consumer cameras

Dark energy camera’s first image Fornax galaxy cluster
The most powerful sky-scanning camera yet built has begun its quest to pin down the mysterious stuff that makes up nearly three-quarters of our Universe.
The Dark Energy Survey's 570-million-pixel camera will scan some 300 million galaxies in the coming five years.
The goal is to discover the nature of dark energy, which is theorised to be responsible for the ever-faster expansion of the Universe.
Its first image, taken 12 September, focussed on the Fornax galaxy cluster.
In time, along with its massive haul of individual galaxies, it        
will study 100,000 galaxy clusters - the largest stable     structures we know of - and 4,000 supernovae, the bright dying throes of stars.      
This enormous survey is a collaboration between US, UK, Brazilian, Spanish and German astronomers.
The phone box-sized Dark Energy Camera or DECam is mounted on the 4m Victor M Blanco telescope at the Cerro Tololo Inter-American Observatory in central Chile.
While it is not the biggest astronomical camera - that honour goes to the Pan-Starss instrument in Hawaii - its extraordinary sensitivity arguably makes it the world's most powerful device of its type.
DECam is particularly sensitive to red and infrared light, to better study cosmic objects as distant as eight billion light-years away.
   What is redshift?
·         The term "redshift" arises from the fact that light from more distant objects shows up on Earth more red than when it left its source
·         The colour shift comes about because of the Doppler effect, which acts to "stretch" or "compress" waves from moving objects
·         It is at work in the sound of a moving siren: an approaching siren sounds higher-pitched and a receding one sounds lower-pitched
·         In the case of light, approaching objects appear more blue and receding objects appear more red
·         The expansion of the Universe is accelerating, so in general, more distant objects are moving away from us (and each other, and everything else) more quickly than nearer ones
·         At cosmic distances, this "cosmological redshift" can greatly affect the colour - the factor by which the wavelength is "stretched" is called redshift

More distant objects are moving away from us - and each other - faster than nearer objects, which causes a shift of their apparent colour toward the red end of the spectrum - a "redshift". But the very stretching of space can cause the same effect.
Careful studies of the shifted light from distant supernovae were what first demonstrated an acceleration in this expansion of the Universe, leading to the 2011 Nobel prize in physics.
What is believed to be causing this increase in the speed of expansion is called dark energy, making up more than 70% of the mass-energy - all of the "stuff" - of the Universe and the focus of the DECam's mission.
Other efforts hope to get to the bottom of the mystery, including the Boss survey and a future space telescope dedicated to the effort called Euclid.
But for now, Will Percival from the University of Portsmouth, a Dark Energy Survey collaborator, said DECam is an exciting prospect.
"This will be the largest galaxy survey of its kind, and the galaxy shapes and positions will tell us a great deal about the nature of the physical process that we call dark energy, but do not currently understand," he said.
The survey will tackle the problem in four ways.
It will study the same kind of supernovae that led to the Nobel prize, in a bid to unravel the "expansion history" of the Universe - when its expansion increased and decreased over billions of years.
It will also map out in 3D the distribution of galaxy clusters, measuring what are known as baryon acoustic oscillations - literally relics of the sound echoes of the Big Bang.

Dark energy and dark matter mysteries
·         Gravity acting across vast distances does not seem to explain what astronomers see
·         Galaxies, for example, should fly apart; some other mass must be there holding them together
·         Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
·         At the greatest distances, the Universe's expansion is accelerating
·         Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
·         The current theory holds that 73% of the Universe is dark energy, 23% is dark matter, and just 4% the kind of matter we know well

By counting the clusters and plotting out when they evidently formed, the survey can feed back to computer models that map out how we think the Universe organised itself in its earliest years.
And studies of the way galaxies and galaxy clusters bend passing light - in a process called weak gravitational lensing - will help to pin down the equally mysterious "dark matter" that is believed to make up more than 80% of the Universe's mass - most of the Universe's stuff that is not energy.
DECam will now be run through a series of tests and will begin the official survey in December.
With each snapshot it acquires, it will see an apparent area of the sky 20 times larger than the full moon.
In its full five-year run, it should capture an eighth of the full sky.
"The achievement of first light through the Dark Energy Camera begins a significant new era in our exploration of the cosmic frontier," said James Siegrist, associate director of science for high-energy physics at the US Department of Energy, which oversaw the instrument's construction.
"The results of this survey will bring us closer to understanding the mystery of dark energy and what it means for the Universe."

Sunday, September 23, 2012

Latest Smartphones Details

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Latest Smartphones

At a time when alomost all telecom companies are vying for a better hold in the smartphone market, new smartphone handsets have been launched in the market keeping in mind the performnance and luxury in mind. Here, we bring you some of the smarphones that have been launched lately. 

Nokia Lumia 920

*Windows 8 OS
*4.5" 720p PureMotionHD+ display (curved glass)
*1.5GHz dual-core Krait processor
*Adreno 225 GPU with 1GB RAM
*PureMotion HD+ (screen color and brightness will adjusts automatically, depending on the ambient light)
*8 megapixel Carl Zeiss with image stabilisation
*1080p video recording (LED Flash)
*NFC and LTE connectivity
*32GB internal memory (+7GB SkyDrive cloud storage)
*2,000 mAh battery
*weight 185 grams
*micro-SIM cards
*lacks memory expansion slot
*Wireless charging

Nokia Lumia 820

*4.3" AMOLED display of WVGA resolution
*Windows 8 OS
*1.5GHz Krait processor and 1GB of RAM
*1650mAh battery
*Fatboy pillow charging (Wireless)
*8GB of built-in storage expanable (and 7GB of SkyDrive cloud storage)
*Carl Zeiss lens and an 8MP sensor
*LTE connectivity
*NFC-based features
*weighs 160gms

Motorola RAZR HD

*4.7" edge-to-edge Super AMOLED display (720p resolution)
*8 MP camera with 1080p video recording and LED flash
*Android 4.0 Ice Cream Sandwich (upgradable to Jelly Bean)
*1GB RAM and Adreno 225 GPU
*Pre-installed Chrome
*2,530mAh battery (16 hrs talk time)
*weighs 146 gms


*3,300mAh battery (21 hrs talktime, 27 hours music streaming, 10 hours video streaming)
*weighs 157 gms
*NFC connectivity
*dual-band Wi-Fi
*Bluetooth 4.0
*HDMI port
*16GB of built-in memory

Hubble Catches Glowing Gas and Dark Dust in a Side – On Spiral

Hubble Catches Glowing Gas and Dark Dust
in a Side – On Spiral

TThe NASA/ESA Hubble Space Telescope has produced a sharp image of NGC 4634, a spiral galaxy seen exactly side-on. Its disk is slightly warped by ongoing interactions with a nearby galaxy, and it is crisscrossed by clearly defined dust lanes and bright nebulae.

NGC 4634, which lies around 70 million light-years from Earth in the constellation of Coma Berenices, is one of a pair of interacting galaxies. Its neighbor, NGC 4633, lies just outside the upper right corner of the frame, and is visible in wide-field views of the galaxy. While it may be out of sight, it is not out of mind: its subtle effects on NGC 4634 are easy to see to a well-trained eye.

Gravitational interactions pull the neat spiral forms of galaxies out of shape as they get closer to each other, and the disruption to gas clouds triggers vigorous episodes of star formation. While this galaxy’s spiral pattern is not directly visible thanks to our side-on perspective, its disk is slightly warped, and there is clear evidence of star formation.

Along the full length of the galaxy, and scattered around parts of its halo, are bright pink nebulae. Similar to the Orion Nebula in the Milky Way, these are clouds of gas that are gradually coalescing into stars. The powerful radiation from the stars excites the gas and makes it light up, much like a fluorescent sign. The large number of these star formation regions is a telltale sign of gravitational interaction.

The dark filamentary structures that are scattered along the length of the galaxy are caused by cold interstellar dust blocking some of the starlight.

Hubble’s image is a combination of exposures in visible light produced by Hubble’s Advanced Camera for Surveys and the Wide Field and Planetary Camera 2.

Tuesday, September 18, 2012

Photographs a Tendril-Like Solar Eruption in Stunning Detail

An Amazing CME Erupts from the Sun Captured August 31, 2012 by NASA's Solar Dynamics Observatory NASA Goddard Space Flight Center via Flickr
We’ve covered some pretty amazing coronal mass ejections (CMEs) here on PopSci, but we might have to crown this one the best yet. Blasting forth from the solar surface at 900 miles per second on August 31, it was captured in all of its tendril-esque glory by NASA’s Solar Dynamics Observatory (SDO). If the image doesn’t look real, rest assured that it is. But the SDO clearly doesn’t capture imagery of the sun in the same way the human eye does. This image is a blended version of the 304 and 171 angstrom wavelengths. I couldn’t begin to tell you why those are the proper wavelengths to capture this sort of thing, but I will endorse the choice. This is one magnificent image of our local star. Oh, and though you would’ve heard about it by now if this particular CME posed any threat to the home planet, you can also rest assure it does not. It was not directed toward Earth, though it was close; it interfered with our magnetosphere enough to cause auroras to appear on the night of September 3. Which is as close as you want a solar eruption like this to get.

Saturday, September 15, 2012

More planets could harbour life

More planets could harbour life

New computer models suggest there could be many more habitable planets out there than previously thought.
Scientists have developed models to help them identify planets in far-away solar systems that are capable of supporting life.
Estimates of habitable planet numbers have been based on the likelihood of them having surface water.
But a new model allows scientists to identify planets with underground water kept liquid by planetary heat.
The research was presented at the British Science Festival in Aberdeen.
Water is fundamental for life as we know it.
Planets too close to their sun lose surface water to the atmosphere through evaporation.
Surface water on planets located in the more frigid distant reaches from their sun is locked away as ice.
The dogma was, for water to exist in its life-giving liquid form, a planet had to be the right distance from its sun - in the habitable zone.
As Sean McMahon, the PhD student from Aberdeen University who is carrying out the work explained: "It's the idea of a range of distances from a star within which the surface of an Earth-like planet is not too hot or too cold for water to be liquid.
"So traditionally people have said that if a planet is in this Goldilocks zone - not too hot and not too cold - then it can have liquid water on its surface and be a habitable planet"
But researchers are starting to think that the Goldilocks theory is far too simple.
Planetary heat
• A planet is warmed by two sources of heat - solar energy and internal heat
• The further away a planet is from its sun the less energy it receives and surface water freezes
• As the distance increases underground water also starts to freeze
• But if the planet is large enough and produces enough internal heat, it could still contain deep reservoirs of liquid water capable of supporting life, no matter how far away from the sun
Planets can receive two sources of heat - heat direct from the star and heat generated deep inside the planet.
As you descend through the crust of the Earth, the temperature gets higher and higher. Even when the surface is frozen, water can exist below ground.
Immense quantities of water in fact - teeming with primitive life.
As Prof John Parnell, also from Aberdeen University said: "There is a significant habitat for microorganisms below the surface of the Earth, extending down several kilometres.
"And some workers believe that the bulk of life on Earth could even reside in this deep biosphere."
So the Aberdeen team are developing models to predict which far-flung planets might harbour underground reservoirs of liquid water with the possibility of alien life.
Explaining their rationale, Mr McMahon said: "If you take into account the possibility of deep biospheres, then you have a problem reconciling that with the idea of a narrow habitable zone defined only by conditions at the surface."
As you move away from the star the amount of heat a planet receives from the star decreases and the surface water freezes - but any water held deep inside will stay liquid if the internal heat is high enough - and that water could support life.
Even a planet so far from the star that it receives almost no solar heat could still maintain underground liquid water.
According to Mr McMahon, "There will be several times more [habitable] planets".