Saturday, September 13, 2014

How to Take Great Pictures of the Northern Lights

How to Take Great Pictures of the Northern Lights:

A group of amateur photographers set up on a beach on Lake Superior near Duluth to photograph the northern lights. To shoot the aurora you'll need a tripod and middle to high end digital camera. Pocket cameras work well in daylight and can be used to shoot bright northern lights, but the images will be noisy. Credit: Bob King

A group of amateur photographers take pictures of an aurora display from a beach along Lake Superior near Duluth. To shoot the aurora you’ll need a tripod and middle to high end digital camera. Pocket cameras work well in daylight and can be used to shoot bright northern lights, but the images will be noisy. Credit: Bob King
Everybody loves pictures of the northern lights? If you’ve never tried to shoot the aurora yourself but always wanted to, here are a few tips to get you started.

"T" stands for a terrific aurora seen last winter from near Duluth, Minn. US. Photo taken with a high-end digital camera (Canon Eos 1 Mark III) at ISO 800, 30-second exposure. Credit: Bob King

“T” stands for a terrific aurora seen last winter near Duluth, Minn. U.S. Photo taken with a high-end digital camera (Canon EOS 1-D Mark III) at ISO 800, 30-second exposure. Credit: Bob King
The strong G3 geomagnetic storm expected tonight should kick out a reasonably bright display, perfect for budding astrophotographers. Assuming the forecasters are correct, you’ll need a few things. A location with a nice open view to the north is a good start. The aurora has several different active zones. There are bright, greenish arcs, which loll about the northern horizon, parallel rays midway up in the northern sky and towering rays and diffuse aurora that can surge past the zenith. Often the aurora hovers low and remains covered by trees or buildings, so find a road or field with good exposure.

15-second time exposure of Vega rising taken with a typical digital pocket camera. Notice the grainy texture. Credit: Bob King

15-second time exposure of Vega rising taken with a typical digital pocket camera. Notice the grain or noise throughout. Credit: Bob King
Second, a tripod. You can do so much with this three-legged beast. No better astro tool in the universe. Even the brightest auroras will require a time exposure of at least 5 seconds. Since no human can be expected to hold a camera steady that long, a tripod is a necessity. After that, it comes down to a camera. Most “point-and-shoot” models have limited time exposure ability, often just 15 seconds. That may be long enough for brighter auroras, but to compensate, you’ll have to increase your camera’s sensitivity to light by increasing the “speed” or ISO. The higher you push the ISO, the grainier the images appear especially with smaller cameras. But you’ll be able to get an image, and that may be satisfaction enough.

I use a Canon EOS-1 Mark III camera to shoot day and night. While not the latest model, it does a nice job on auroras. The 16-35mm zoom wide-angle lens is my workhorse as the aurora often covers a substantial amount of sky. My usual routine is to monitor the sky. If I see aurora padding across the sky, I toss the my equipment in the car and drive out to one of several sites with a clear exposure to the north. Once the camera meets tripod, here’s what to do:

A bright, very active aurora. I used my zoom lens at 16mm at f/2.8 and a 15-second exposure at ISO 800.

A bright, active aurora. I used my zoom lens at 16mm at f/2.8 and about a 15-second exposure at ISO 800. Credit: Bob King
* Put the camera in manual mode and make sure my focus is set to infinity. Focusing is critical or the stars will look like blobs and the aurora green mush. There are a couple options. Use autofocus on a cloud or clouds in the daytime or the moon at night. Both are at “infinity” in the camera’s eye. Once focused at infinity, set the camera to manual and leave it there the rest of the evening to shoot the aurora. OR … note where the little infinity symbol (sideways 8) is on your lens barrel and mark it with a thin sharpie so you can return to it anytime. You can also use your camera in Live View mode, the default viewing option for most point-and-shoot cameras where you compose and frame live. Higher-end cameras use a viewfinder but have a Live View option in their menus. Once in Live View, manually focus on a bright star using the back of the camera. On higher-end cameras you can magnify the view by pressing on the “plus” sign. This allows for more precision focus.

* Set the lens to its widest open setting, which for my camera is f/2.8. The lower the f-stop number, the more light allowed in and the shorter the exposure. Like having really big pupils! You want to expose the aurora in as short a time as possible because it moves. Longer exposures soften its appearance and blur exciting details like the crispness of the rays.

My friend Glenn takes a night sky shot silhouetted against the northern lights. Credit: Bob King

A friend takes a night sky shot silhouetted against the glow of the northern lights. Credit: Bob King
*  Set the ISO to 800 for brighter auroras or 1600 for fainter ones and set the time to 30-seconds. If the aurora is bright and moving quickly, I’ll decrease exposure times to 10-15 seconds. The current crop of high end cameras now have the capacity to shoot at ISOs of 25,000. While those speeds may not give the smoothest images, dialing back to ISO 3200 and 6400 will make for photos that look like they were shot at ISO 400 on older generation cameras. A bright aurora at ISO 3200 can be captured in 5 seconds or less.

* Compose the scene in the viewfinder. If you’re lucky or plan well, you can include something interesting in the foreground like a building, a picturesque tree or lake reflection.

* OK, ready? Now press the button. When the image pops up on the viewing screen, does the image seem faint, too bright or just right. Make exposure adjustments as needed. If you need to expose beyond the typical maximum of 30 seconds, you can hold the shutter button down manually or purchase a cable release to hold it down for you.

It’s easy, right? Well then, why did it take me 400 words to explain it??? Have fun and good luck in your photography.

Tagged as:
aurora,
photography
Posted by Nelio Inacio at 6:08 AM 0 comments

Friday, September 12, 2014

Elemental Mystery: Lithium Is Also Rare Outside Of The Milky Way

Elemental Mystery: Lithium Is Also Rare Outside Of The Milky Way:



An image of globular cluster M54 taken by the Very Large Telescope Survey Telescope at the European Southern Observatory's Paranal Observatory in northern Chile. Credit: ESO

An image of globular cluster M54 taken by the Very Large Telescope Survey Telescope at the European Southern Observatory’s Paranal Observatory in northern Chile. Credit: ESO
This new picture of M54 — a part of a satellite galaxy to the Milky Way called the Sagittarius Dwarf Galaxy — is part of a “test case” astronomers have to figure out a mystery of missing lithium.

For decades, astronomers have been aware of a dearth of lithium in our own galaxy, the Milky Way. This image from the Very Large Telescope’s Survey Telescope represents the first effort to probe for the element outside of our galaxy.

“Most of the light chemical element lithium now present in the Universe was produced during the Big Bang, along with hydrogen and helium, but in much smaller quantities,” the European Southern Observatory stated.

“Astronomers can calculate quite accurately how much lithium they expect to find in the early Universe, and from this work out how much they should see in old stars. But the numbers don’t match — there is about three times less lithium in stars than expected. This mystery remains, despite several decades of work.”

In any case, observations of M54 show that the amount of lithium there is similar to the Milky Way — meaning that the lithium problem is not confined to our own galaxy. A paper based on the research was published in the Monthly Notices of the Royal Astronomical Society. The research was led by Alessio Mucciarelli at the University of Bologna in Italy.

Source: European Southern Observatory

Tagged as:
lithium,
m54,
messier 54,
sagitarrius dwarf galaxy,
very large telescope survey telescope
Posted by Nelio Inacio at 10:05 AM 0 comments

Aurora Watch! Two Solar Particle Blasts Could Start Smacking Into Earth Friday

Aurora Watch! Two Solar Particle Blasts Could Start Smacking Into Earth Friday:



A solar blast erupts in this picture captured by the Solar and Heliospheric Observatory on Sept. 10, 2014. Credit: ESA / NASA / SOHO

A solar blast erupts in this picture captured by the Solar and Heliospheric Observatory on Sept. 10, 2014. Credit: ESA / NASA / SOHO
Bim, bam, smash! The Sun hurled two clouds of particles in our general direction, putting space weather watchers on alert. There’s now a high chance of auroras on Sept. 12 (Friday), according to the National Oceanic and Atmospheric Administration, with more activity possible during the weekend.

The coronal mass ejections erupted Sept. 9 and Sept. 10 from sunspot AR2158. The Sept. 10 flare packed the strongest class punch the sun has, an X-flare, which briefly caused HF radio blackouts on Earth. We have some amateur shots of the sunspot and Sun below.

“Radio emissions from shock waves at the leading edge of the CME suggest that the cloud tore through the sun’s atmosphere at speeds as high as 3,750 km/s [2,330 miles per second],” wrote SpaceWeather.com. “That would make this a very fast moving storm, and likely to reach Earth before the weekend. Auroras are definitely in the offing.”

Photographer John Chumack captured the Sun and AR2158 in these pictures from Monday (Sept. 8). If you’ve got some great Sun shots to share, be sure to put it on our Universe Today Flickr group!

Sunspot AR2158 taken on Sept. 8, 2014. Credit: John Chumack

Sunspot AR2158 taken on Sept. 8, 2014. Credit: John Chumack
The Sun on Sept. 8, 2014, including active sunspots. Credit: John Chumack

The Sun on Sept. 8, 2014, including active sunspots. Credit: John Chumack
Tagged as:
ar2158,
sunspot,
X-class
Posted by Nelio Inacio at 10:04 AM 0 comments

A Lurking Companion Star Explains Enigmatic Supernova

A Lurking Companion Star Explains Enigmatic Supernova:



The above sequence depicts a rare supernova explosion. The topic panel

The above sequence depicts a rare supernova explosion. Hubble images (bottom panel) correspond to an artist’s conception (top panel). Credit: Kavli IPMU / NASA / Gastón Folatelli
Massive stars end their lives dramatically. Once the nuclear fuel deep within their cores is spent, there’s no longer any outward pressure to push against gravity, and the star collapses. But while the inner layers fall in to form a black hole or a neutron star, the outer layers fall faster, hitting the inner layers, and rebounding in a huge supernova explosion.

That’s the textbook definition. But some of these supernovae defy explanation. In 2011 one such explosion, dubbed SN 2011dh, pierced the Whirlpool galaxy, roughly 24 million-light years away. At the time astronomers were baffled. But now, thanks to NASA’s Hubble Space Telescope, they’ve discovered a companion star to this rare supernova and fit the final puzzle pieces together.

SN 2011dh is a Type IIb supernova, unusual in that it contains very little hydrogen and unexplainable via a textbook definition. Even so, astronomers can shed light on the progenitor star simply by digging through archived images from HST. Thanks to HST’s wealth of data and the fact that it observes the Whirlpool galaxy often, two independent research teams both detected a source — a yellow supergiant star — at the right location.

But astronomers don’t think yellow supergiant stars are capable of becoming supernovae … at least not in isolation.

At this point, controversy arose within the astronomical community. Several experts proposed that the observation was a false cosmic alignment and that the actual progenitor was an unseen massive star. Other experts proposed that the progenitor could have been the yellow supergiant, but that it must have belonged in a binary star system.

When a massive star in a binary system overflows its Roche lobe — the region outside that star where gravity dominates — it can pour material onto its smaller companion, therefore losing its hydrogen envelope and shrinking in mass.

At the time the mass-donor explodes, the companion star should be a massive blue star, having gained material during the mass transfer. Its high temperature should also cause it to emit mostly in the ultraviolet range, therefore rendering it invisible in any visible images.

So Gastón Folatelli from the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) and colleagues decided to take a second look at the mysterious supernova in ultraviolet light. And their observations matched their expectations. The original supernova had faded, and a different point source had taken its place.

“One of the most exciting moments in my career as an astronomer was when I displayed the newly arrived HST images and saw the object right there, where we had anticipated it to be all along,” said Folatelli in a news release.

The research illustrates the intricate interplay between theory and observation. Astronomers often rely on theories long before they gain the technology necessary to provide the correct observations or spend years trying to explain odd observations with complex theoretical modeling. More often, however, the two coexist as theory and observation banter back and forth.

The findings have been published in the Astrophysical Journal Letters and are available online.

Tagged as:
Type II Supernovae,
yellow hypergiant
Posted by Nelio Inacio at 10:04 AM 0 comments

‘Venus Zone': The Anti-Habitable Area Around A Star That Can Breed Hell

‘Venus Zone': The Anti-Habitable Area Around A Star That Can Breed Hell:



A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL

A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL
Our hothouse planet of the solar system, Venus, is possibly a product of how close it is to the Sun, new research reveals. The team who have come up with a definition of a “Venus zone” around stars, saying that knowing where this area is could help pin down other areas that are more habitable for potential life.

“We believe the Earth and Venus had similar starts in terms of their atmospheric evolution,” stated lead author Stephen Kane, an astronomer at San Francisco State University. “Something changed at one point, and the obvious difference between the two is proximity to the Sun.”

The habitable region around a star is poorly understood because scientists don’t quite know what conditions are necessary for life. It usually refers to the area where liquid water is possible, although this also depends on the climate of the planet itself. Clouds, terrain and atmospheric composition are just some of the variables that could affect habitability.

Artist’s impression of a massive asteroid belt in orbit around a star. Credit: NASA-JPL / Caltech / T. Pyle (SSC)

Artist’s impression of a massive asteroid belt in orbit around a star. Credit: NASA-JPL / Caltech / T. Pyle (SSC)
To better figure out where potential Venus-like exoplanets lurk, Kane’s team used data from the planet-hunting Kepler Space Telescope and examined solar flux — or how much solar energy a planet gets — to figure out where the Venus zone would be. The zone is then defined between two regions: where a planet could have the “runaway greenhouse effect” seen on Venus, and the spot where the planet is so close to its star that energy would wear away its atmosphere.

The first step would be pinpointing which planets reside within these zones. In future decades, astronomers could then examine the planetary atmospheres with telescopes to learn more about how they are composed — and how similar they are to Earth or Venus. Meanwhile, Kane’s team plans to model if carbon in the planet’s atmosphere could affect the boundaries of the zone.

“If we find all of these planets in the Venus Zone have a runaway greenhouse-gas effect, then we know that the distance a planet is from its star is a major determining factor,” Kane stated. “That’s helpful to understanding the history between Venus and Earth.”

A preprint version of the paper is available on the Arxiv website. The research has been accepted for publication in Astrophysical Journal Letters.

Source: San Francisco State University

Tagged as:
venus zone
Posted by Nelio Inacio at 10:03 AM 0 comments

Astrophoto: The Sun as a Work of Art

Astrophoto: The Sun as a Work of Art:



A stylized Coronal Mass Ejection: The Sun as work of art. Credit and copyright: Rick Ellis.

A stylized Coronal Mass Ejection: The Sun as work of art. Credit and copyright: Rick Ellis.
Here’s yesterday’s solar flare as seen with a little flair added! Astrophotographer Rick Ellis from Toronto, Canada created this “artsy” Sun by using a series of photoshop filters and effects. He tinkered with the contrast at specific color ranges, applied “equalization,” and used a filter called “accented edges.”

“Then I posterized it and ran it through the “posterize edges” filter which really brings out many details,” Rick said via email.

Rick admitted to some confusion about the difference between solar flares and coronal mass ejections, and so we figured this might be a good time to explain. They do have several similarities, however: both solar flares and CMEs are energetic events on the Sun that are both associated with high energy particles, and they both depend on magnetic fields on the Sun.

In the case of a CME, coronal material is ejected into space at high speeds. According to Berkeley University the most obvious difference between a solar flare and a CME is the spatial scale on which they occur.

“Flares are local events as compared to CMEs which are much larger eruptions of the corona,” says the Berkeley webpage, and sometimes a CME can be larger than the Sun itself. Solar flares and coronal mass ejections often occur together, but each can also take place in the absence of the other.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

Tagged as:
solar flare,
sun
Posted by Nelio Inacio at 10:03 AM 0 comments

Clear Skies Tonight? Go Out and See the Aurora

Clear Skies Tonight? Go Out and See the Aurora:



A low arc, glowing green from excited oxygen, spans the northern sky around 10:30 p.m Central Daylight Time from Duluth, Minn. The Big Dipper is off to the left. Credit: Bob King

A low arc, glowing green from excited oxygen, spans the northern sky around 9:30 p.m Central Daylight Time from Duluth, Minn. this evening September 11, 2014 at 9:30 p.m. CDTThe Big Dipper is off to the left. Credit: Bob King
Talk of aurora is in the air.  Our earlier story today by Elizabeth Howell alerted you to the possibility of northern lights. Well, it’s showtime!  As of 10:30 p.m. Eastern Daylight Time, the aurora has been active low in the northern sky.

Subtle pink rays stand above the green arc at 9:35 p.m. CDT. Credit: Bob King

Subtle pink rays stand above the green arc at 9:35 p.m. CDT. Credit: Bob King
From Duluth, Minn. U.S.,  a classic green arc low in the northern sky competed with the light of the rising gibbous moon. Once my eyes were dark-adapted, faint parallel rays stood streaked the sky above the arc. NOAA space weather forecasters expect this storm to peak between 1 a.m. CDT and sunrise Friday morning September 12 at a G2 or moderate level. Skywatchers across the northern tier of states and southern Canada should see activity across the northern sky. Moonlight will compromise the show to some degree

The approximate extent of the auroral oval forecast for 11:30 p.m. CDT from Ovation. Credit: NOAA

The approximate extent of the auroral oval forecast for 11:30 p.m. CDT from Ovation. Credit: NOAA
This is only the start. Things really kick into gear Friday night and Saturday morning with a G3 strong geomagnetic storm. Auroras might be visible as far south as Illinois and Kansas.

We’ll keep you in touch with the storm with regular updates over the next couple days. Here are some links to check during the night as you wait for the aurora to possibly put in an appearance at your house:

* Ovation oval – shows the approximate extent of the auroral oval that looks like a cap centered on Earth’s geomagnetic pole. During storms, the oval extends south into the northern U.S. and farther.

* Kp index – indicator of magnetic activity high overhead and updated every three hours. A Kp index of “5” means the onset of a minor storm; a Kp of “6”, a moderate storm.

* NOAA space weather forecast

* Advanced Composition Explorer (ACE) satellite plots – The magnetic field direction of the arriving wind from the sun. The topmost graph, plotting Bz, is your friend. When the curve drops into the negative zone that’s good! A prolonged stay at -10 or lower increases the chance of seeing the aurora.

Tagged as:
aurora,
flare,
northern lights,
oval
Posted by Nelio Inacio at 10:02 AM 0 comments

Lunar Love: Stunning Shots Abound In Phases Around The SuperMoon

Lunar Love: Stunning Shots Abound In Phases Around The SuperMoon:



The gibbous moon shines on Sept. 5, 2014. Credit: Christian Kamber

The gibbous moon shines on Sept. 5, 2014. Credit: Christian Kamber
While the SuperMoon of earlier this week got a lot of attention — and rightly so, given the Moon was closest in its orbit to Earth when it was full — the waning and waxing phases around our celestial neighbor are also beautiful. Haunting, in fact.

These shots were taken by members of our Universe Today Flickr pool, with the moon either entering or exiting the full moon phase. Got some stunning astronomy shots to share? Feel free to add your contributions to the group (which says you will give us permission to publish) and we may include them in a future story.

The moon in its waning gibbous phase on Sept. 12, 2014. Photo taken with a Canon 700D attached to a Maksutov 127mm telescope. Credit: Sarah&Simon Fisher

The moon in its waning gibbous phase on Sept. 12, 2014. Photo taken with a Canon 700D attached to a Maksutov 127mm telescope. Credit: Sarah&Simon Fisher
The moon shines red in this photo taken from Newcastle upon Tyne, England on Sept. 11, 2014. Credit: David Blanchflower

The moon shines red in this photo taken from Newcastle upon Tyne, England on Sept. 11, 2014. Credit: David Blanchflower
The large craters Atlas (left) and Hercules (below) on the moon. Taken using a Canon 1100D. Credit: Paul M. Hutchinson

The large craters Atlas (left) and Hercules (below) on the moon. Taken using a Canon 1100D. Credit: Paul M. Hutchinson
Tagged as:
astrophotography,
flickr,
Supermoon
Posted by Nelio Inacio at 10:02 AM 0 comments

Wow! Water Ice Clouds Suspected In Brown Dwarf Beyond The Solar System

Wow! Water Ice Clouds Suspected In Brown Dwarf Beyond The Solar System:



Artist's conception of brown dwarf WISE J085510.83-071442.5, which may host water ice clouds in its atmosphere. Credit: Rob Gizis (CUNY BMCC / YouTube (screenshot)

Artist’s conception of brown dwarf WISE J085510.83-071442.5, which may host water ice clouds in its atmosphere. Credit: Rob Gizis (CUNY BMCC / YouTube (screenshot)
What are planetary atmospheres made of? Figuring out the answer to that question is a big step on the road to learning about habitability, assuming that life tends to flourish in atmospheres like our own.

While there is a debate about how indicative the presence of, say, oxygen or water is of life on Earth-like planets, astronomers do agree more study is required to learn about the atmospheres of planets beyond our solar system.

Which is why this latest find is so exciting — one astronomy team says it may have spotted water ice clouds in a brown dwarf (an object between the size of a planet and a star) that is relatively close to our solar system. The find is tentative and also in an object that likely does not host life, but it’s hope that telescopes may get better at examining atmospheres in the future.

The object is called WISE J085510.83-071442.5, or W0855 for short. It’s the coldest brown dwarf ever detected, with an average temperature between 225 degrees Kelvin (-55 Fahrenheit, or -48 Celsius) and 265 Kelvin (17 Fahrenheit, or -8 Celsius.) It’s believed to be about three to 10 times the mass of Jupiter.

Astronomers looked at W0855 with an infrared mosaic imager on the 6.5-meter Magellan Baade telescope, which is located at Las Campanas Observatory in Chile. The team obtained 151 images across three nights in May 2014.



Astronomers plotted the brown dwarf on a color-magnitude chart, which is a variant of famous Hertzsprung-Russell diagram used to learn more about stars by comparing their absolute magnitude against their spectral types. “Color-Magnitude diagrams are a tool for investigating atmospheric properties of the brown dwarf population as well as testing model predictions,” the authors wrote in their paper.

Based on previous work on brown dwarf atmospheres, the team plotted W0855 and modelled it, discovering it fell into a range that made water ice clouds possible. It should be noted here that water ice is known to exist in all four gas giants of our own Solar System: Jupiter, Saturn, Uranus, and Neptune.

“Non-equilibrium chemistry or non-solar metallicity may change predictions,” the authors cautioned in their paper. “However, using currently available model approaches, this is the first candidate outside our own solar system to have direct evidence for water clouds.”

The research, led by the Carnegie Institution for Science’s Jacqueline Faherty, was published in Astrophysical Journal Letters. A preprint version of the paper is available on Arxiv.

Source: Carnegie Institution for Science

Tagged as:
brown dwarf,
W0855,
water ice,
WISE J085510.83-071442.5
Posted by Nelio Inacio at 10:01 AM 0 comments

An X-ray Tapestry

An X-ray Tapestry:

posted by chandra
on Wed, 2014-09-10 09:50


Puppis A

The destructive results of a powerful supernova explosion reveal themselves in a delicate tapestry of X-ray light, as seen in this image from NASA's Chandra X-Ray Observatory and the European Space Agency's XMM-Newton.

The image shows the remains of a supernova that would have been witnessed on Earth about 3,700 years ago. The remnant is called Puppis A, and is around 7,000 light years away and about 10 light years across. This image provides the most complete and detailed X-ray view of Puppis A ever obtained, made by combining a mosaic of different Chandra and XMM-Newton observations. Low-energy X-rays are shown in red, medium-energy X-rays are in green and high energy X-rays are colored blue.

More information at http://chandra.harvard.edu/photo/2014/puppisa/index.html

-Megan Watzke, CXC
Disclaimer: This service is provided as a free forum for registered users. Users' comments do not reflect the views of the Chandra X-ray Center and the Harvard-Smithsonian Center for Astrophysics.

Please note this is a moderated blog. No pornography, spam, profanity or discriminatory remarks are allowed. No personal attacks are allowed. Users should stay on topic to keep it relevant for the readers.

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Posted by Nelio Inacio at 9:30 AM 0 comments

NASA Launches New Era of Earth Science from Space Station

NASA Launches New Era of Earth Science from Space Station:

ISS International Space Station
Image Credit: NASA


September 08, 2014

The launch of a NASA ocean winds sensor to the International Space Station (ISS) this month inaugurates a new era of Earth observation that will leverage the space station's unique vantage point in space. Before the end of the decade, six NASA Earth science instruments will be mounted to the station to help scientists study our changing planet.

The first NASA Earth-observing instrument to be mounted on the exterior of the space station will launch from Cape Canaveral Air Force Station, Florida, on the next SpaceX Commercial Resupply Services flight, currently targeted for no earlier than Sept. 19. ISS-RapidScat will monitor ocean winds for climate research, weather predictions and hurricane monitoring from the space station.

The second instrument is the Cloud-Aerosol Transport System (CATS), a laser instrument that will measure clouds and the location and distribution of airborne particles such as pollution, mineral dust, smoke, and other particulates in the atmosphere. CATS will follow ISS-RapidScat on the fifth SpaceX space station resupply flight, targeted for December.

"We're seeing the space station come into its own as an Earth-observing platform," said Julie Robinson, chief scientist for the International Space Station Program at NASA's Johnson Space Center in Houston. "It has a different orbit than other Earth remote sensing platforms. It's closer to Earth, and it sees Earth at different times of day with a different schedule. That offers opportunities that complement other Earth-sensing instruments in orbit today."

The space station-based instruments join a fleet of 17 NASA Earth-observing missions currently providing data on the dynamic and complex Earth system. ISS-RapidScat and CATS follow the February launch of the Global Precipitation Measurement Core Observatory, a joint mission with the Japan Aerospace Exploration Agency, and the July launch of the Orbiting Carbon Observatory-2, making 2014 one of the busiest periods for new NASA Earth science missions in more than a decade.

Most of the agency's free-flying, Earth-observing satellites orbit the planet over the poles at altitudes higher than 400 miles in order to gather data from all parts of the planet. Although the space station does not pass over Earth's polar regions, its 240-mile-high orbit does offer logistical and scientific advantages.

"With the space station we don't have to build a spacecraft to gather new data -- it's already there," said Stephen Volz, associate director of flight programs in the Earth Science Division at NASA Headquarters in Washington. "The orbit enables rare, cross-disciplinary observations when the station flies under another sensor on a satellite. Designing instruments for the space station also gives us a chance to do high-risk, high-return instruments in a relatively economical way."

The data provided by ISS-RapidScat will support weather and marine forecasting, including tracking storms and hurricanes. The station's orbit will allow the instrument to make repeated, regular observations over the same locations at different times of day, providing the first near-global measurements of how winds change throughout the day. ISS-RapidScat was built by NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

CATS is a laser remote-sensing instrument, or lidar, that measures clouds and tiny aerosol particles in the atmosphere. These atmospheric components play a critical part in understanding how human activities such as pollution and fossil fuel burning contribute to climate change. CATS was built by NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Two additional NASA Earth science instruments are scheduled to launch to the station in 2016. The Stratospheric Aerosol and Gas Experiment III (SAGE III), will measure aerosols, ozone, water vapor and other gases in the upper atmosphere to help scientists assess how the ozone layer is recovering and better understand global climate change. SAGE III was developed by NASA's Langley Research Center in Hampton, Virginia, and built by Ball Aerospace of Boulder, Colorado.

The Lightning Imaging Sensor (LIS) will detect and locate lightning over tropical and mid-latitude regions of the globe. The first LIS was launched in 1997 as part of NASA's Tropical Rainfall Measuring Mission. The sensor will monitor lightning for Earth science studies and provide cross-sensor calibration and validation with other space-borne instruments and ground-based lightning networks. LIS was developed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

In July, NASA selected proposals for two new instruments that will observe changes in global vegetation from the space station, giving scientists new ways to observe how forests and ecosystems are affected by changes in climate and land use change. Both sensors will be completed before the end of the decade.

The Global Ecosystem Dynamics Investigation (GEDI) will use a laser-based system to study forest canopy structure in a range of ecosystems, from the tropics to the high northern latitudes. The observations will help scientists better understand the changes in carbon storage within forests from both human activities and natural climate variations. GEDI is managed by scientists at the University of Maryland, College Park.

The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) is a high-resolution multiple wavelength thermal imaging spectrometer that will study water use and water stress in vegetation. Measurements of the loss of water from growing leaves and evaporation from the soil will help reveal how ecosystems change with climate and provide a critical link between the water cycle and plant health in both natural and agricultural ecosystems. ECOSTRESS is managed by JPL.

The space station provides several capabilities useful to both instruments. The space station orbit provides more observation time of forests and vegetation over temperate land masses than possible with the polar orbit commonly used for other types of Earth observations. The GEDI laser requires significant power resources, which the space station can provide.

For more information on Earth science activities aboard the space station, visit:

http://www.nasa.gov/issearthscience

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA's Earth science activities in 2014, visit:

http://www.nasa.gov/earthrightnow

Steve Cole / Joshua Buck
NASA Headquarters, Washington

202-358-0918 / 202-358-1100

stephen.e.cole@nasa.gov / jbuck@nasa.gov


Alan Buis

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-0474

alan.buis@jpl.nasa.gov

2014-301
Posted by Nelio Inacio at 9:29 AM 0 comments

Bright Clumps in Saturn Ring Now Mysteriously Scarce

Bright Clumps in Saturn Ring Now Mysteriously Scarce:

Shadows and Rings
Cassini spied just as many regular, faint clumps in Saturn's narrow F ring, like those pictured here, as Voyager did, but it saw hardly any of the long, bright clumps that were common in Voyager images. Image credit: NASA/JPL-Caltech/SSI
› Full image and caption


September 08, 2014

Compared to the age of the solar system -- about four-and-a-half billion years -- a couple of decades are next to nothing. Some planetary locales change little over many millions of years, so for scientists who study the planets, any object that evolves on such a short interval makes for a tempting target for study. And so it is with the ever-changing rings of Saturn.

Case in point: Saturn's narrow, chaotic and clumpy F ring. A recent NASA-funded study compared the F ring's appearance in six years of observations by the Cassini mission to its appearance during the Saturn flybys of NASA's Voyager mission, 30 years earlier. The study team found that, while the overall number of clumps in the F ring remained the same, the number of exceptionally bright clumps of material plummeted during that time. While the Voyagers saw two or three bright clumps in any given observation, Cassini spied only two of the features during a six-year period. What physical processes, they wondered, could cause only the brightest of these features to decline sharply?

While a variety of features in Saturn's many rings display marked changes over multiple years, the F ring seems to change on a scale of days, and even hours. Trying to work out what is responsible for the ring's tumultuous behavior is a major goal for ring scientists working on Cassini.

"Saturn's F ring looks fundamentally different from the time of Voyager to the Cassini era," said Robert French of the SETI Institute in Mountain View, California, who led the study along with SETI Principal Investigator Mark Showalter. "It makes for an irresistible mystery for us to investigate."

The researchers hypothesize that the brightest clumps in the F ring are caused by repeated impacts into its core by small moonlets up to about 3 miles (5 kilometers) wide, whose paths around Saturn lie close to the ring and cross into it every orbit. They propose that the diminishing number of bright clumps results from a drop in the number of these little moonlets between the Voyager and Cassini eras.

As for what might have caused the moonlets to become scarce, the team has a suspect: Saturn's moon Prometheus. The F ring encircles the planet at a special location, near a place called the Roche limit -- get any closer to Saturn than this, and tidal forces from the planet's gravity tear apart smaller bodies. "Material at this distance from Saturn can't decide whether it wants to remain as a ring or coalesce to form a moon," French said. Prometheus orbits just inside the F ring, and adds to the pandemonium by stirring up the ring particles, sometimes leading to the creation of moonlets, and sometimes leading to their destruction.

Every 17 years, the orbit of Prometheus aligns with the orbit of the F ring in such a way that its influence is particularly strong. The study team thinks this periodic alignment might spur the creation of many new moonlets. The moonlets would then crash repeatedly through the F ring, like cars in a Hollywood high-speed chase, creating bright clumps as they smash across lanes of ring material. Fewer clumps would be created as time goes by, because the moonlets themselves are eventually destroyed by all the crashes.

As with any good scientific hypothesis, the researchers offer a way to test their ideas. It happens that the Voyager encounters with Saturn occurred a few years after the 1975 alignment between Prometheus and the F ring, and Cassini was present for the 2009 alignment. If the moon's periodic influence is indeed responsible for creating new moonlets, then the researchers expect that Cassini would see the F ring return to a Voyager-like number of bright clumps in the next couple of years.

"Cassini's continued presence at Saturn gives us an interesting opportunity to test this prediction," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, who was not involved in the study. "Whatever the result, we're certain to learn something valuable about how rings, as well as planets and moons, form and evolve."

The study by French and colleagues was published in the online edition of the Journal Icarus on July 15, 2014.

NASA's Jet Propulsion Laboratory manages the Voyager and Cassini-Huygens missions for NASA's Science Mission Directorate at NASA Headquarters in Washington.

More information about Cassini is available at:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

Preston Dyches 818-354-5011

Jet Propulsion Laboratory, Pasadena, Calif.

preston.dyches@jpl.nasa.gov



Seth Shostak 650-960-4530

SETI Institute, Mountain View, Calif.

seth@seti.org



2014-302
Posted by Nelio Inacio at 9:29 AM 0 comments

Spitzer's SPLASH Project Dives Deep for Galaxies

Spitzer's SPLASH Project Dives Deep for Galaxies:

Scientists
Scientists "fish" for galaxies in this playful, digitally altered photo. The researchers are part of a program called SPLASH, which is using NASA's Spitzer Space Telescope to dive deep into the cosmic sea and find some of the most remote galaxies known. Early results are turning up surprisingly big "fish" -- massive galaxies -- in the darkest reaches of the universe, dating back to a time when our universe was less than one billion years old. Image credit: NASA/JPL-Caltech
› Full image and caption


September 09, 2014

A new survey of galaxies by NASA's Spitzer Space Telescope is taking a plunge into the deep and uncharted waters of our cosmos. In one of the longest surveys the telescope will have ever performed, astronomers have begun a three-month expedition trawling for faint galaxies billions of light-years away.

The results are already yielding surprises.

"If you think of our survey as fishing for galaxies in the cosmic sea, then we are finding many more big fish in deep waters than previously expected," said Charles Steinhardt of NASA's Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology in Pasadena. Steinhardt is lead author of a new study appearing in the Astrophysical Journal Letters.

These early results from the SPLASH project, an international effort officially called the Spitzer Large Area Survey with Hyper-Suprime-Cam, build on previous evidence from Spitzer and other telescopes showing that the universe's earliest galaxies are more massive than expected. The project is turning up hundreds of hefty galaxies 100 times the mass of our own Milky Way, dating back to a time when our universe was less than one billion years old. (Our universe is 13.8 billion years old.)

The findings cast doubt on current models of galaxy formation, which struggle to explain how these remote and young galaxies grew so big so fast.

"Galaxies were being assembled faster than we thought, and we can only see this by finding large numbers of them with a survey like SPLASH," said Peter Capak, also of IPAC, and principal investigator of SPLASH.

While astronomers have seen such massive galaxies before, SPLASH is unique in finding large numbers of them. Now that Spitzer is in the "warm" phase of its mission, it dedicates more time to long-term projects such as this one. The telescope ran out of the coolant needed to chill some of its instruments in 2009, but two of its infrared channels work at the slightly warmer temperature. With fewer instruments, the telescope spends more time surveying large patches of sky.

By the end of the SPLASH survey, Spitzer will have spent 2,475 hours staring at two sky fields known as the Cosmic Evolution Survey (COSMOS) and Subaru/XMM-Newton deep field (SXDS), equivalent in size to about eight full moons. These are two of the darkest patches of sky, away from the plane of our Milky Way galaxy's flat spiral disk and its bright starlight. Many telescopes have studied these regions extensively at multiple wavelengths of light, spying the faint glow of millions of galaxies beyond our own. Spitzer's infrared vision helps weigh the galaxies, revealing their masses.

Astronomers are surprised by the early SPLASH results and its catch of "big fish." Current theories of star formation hold that the very first galaxies collided and merged, bulking up in size. In these models, the stars formed in bursts as these smaller galaxies smashed into each other. But this process takes time. Spitzer's finding of massive galaxies in an era between 800 and 1,600 million years after the birth of our universe barely leaves enough time for the galaxies' roughly one hundred billion stars to have formed.

"It's really hard to form something so massive so quickly," said Josh Speagle, co-author of the study from Harvard University, Cambridge, Massachusetts. "So it's entirely possible that these galaxies have been forming stars continuously since the moment they were born."

Another explanation is that the first-ever galaxies got their foothold in the universe sooner than thought. Astronomers think the first galaxies formed around 500 million years after the Big Bang. If galaxies started forming earlier than this, by about 400 million years after the Big Bang, then they might have had the time needed to merge with other galaxies and ultimately grow into the behemoths found by Spitzer.

Follow-up observations with a host of telescopes are now being planned to figure out exactly how these galaxies got so big. Japan's Subaru telescope atop Mauna Kea in Hawaii will collect deep optical images of the galaxies over the course of several years.

The technical Astrophysical Journal Letters paper is online at

http://iopscience.iop.org/2041-8205/791/2/L25/

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit:

http://spitzer.caltech.edu

http://www.nasa.gov/spitzer

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-4673

whitney.clavin@jpl.nasa.gov


2014-303
Posted by Nelio Inacio at 9:28 AM 0 comments

NASA Research Aids Response to California Napa Quake

NASA Research Aids Response to California Napa Quake:

NASA's UAVSAR Studies Ground Deformation from Napa California Quake
NASA Uninhabited Aerial Vehicle Synthetic Aperture Radar data from flights over Napa Valley, California, on May 29 and Aug. 29 were used to measure ground deformation from the Aug. 24 magnitude 6.0 quake in South Napa. The analyses found the quake's surface rupture was more complex than anticipated. Image credit: NASA/JPL-Caltech/ASI/Google Earth
› Full image and caption


September 10, 2014

NASA data and expertise are proving invaluable in California's ongoing response to the Aug. 24 magnitude 6.0 earthquake in Napa Valley, northeast of San Francisco. The quake was the strongest to occur in the San Francisco Bay Area in a quarter-century and caused significant regional damage.

Analyses by scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, of airborne data from NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), GPS data and radar imagery from the Italian Space Agency's COSMO-SkyMed satellites, are revealing important details of how the ground deformed in the region and the nature of the fault movements. In addition, a NASA-funded disaster decision support system has provided a series of rapid-response data maps to decision makers at the California Earthquake Clearinghouse. Those maps are being used to better direct response efforts.

NASA has been monitoring active earthquake faults in California using a variety of remote sensing and ground-based techniques. The JPL-developed UAVSAR, in use since 2009, is an L-band Interferometric Synthetic Aperture Radar instrument that flies mounted underneath a NASA C-20A Earth science research aircraft from NASA's Armstrong Flight Research Center, Edwards, California. UAVSAR is able to detect minute changes in Earth's surface that occur over time between flights of the instrument. UAVSAR has monitored the Napa area about every six months since November 2009.

A comparison of UAVSAR data collected on May 29, 2014, three months before the quake, and on Aug. 29, 2014, five days after the quake, reveals that multiple strands of the fault slipped near the quake's epicenter. A new UAVSAR image showing these changes is available at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18801

The image colors represent the amount of ground motion between the two flights in the direction from a point on the ground to the instrument, which flies at an altitude of 41,000 feet (12,497 meters). Preliminary results indicate several inches/centimeters of horizontal slip occurred on the various strands of the fault.

Further UAVSAR data analyses will reveal how deep beneath Earth's surface the faults slipped and the amount of the slip. Initial GPS analyses, shown in the image by the yellow arrows, indicate an average slip of nearly 23.6 inches (60 centimeters) along a 9.3-mile-long (15-kilometer) fault. That is equivalent to a magnitude 6.1 earthquake. This suggests that the strands of the fault continued to slip after the main earthquake, but did not produce any large aftershocks.

The Aug. 29 UAVSAR flight was conducted to assess if the earthquake damaged any of the water conveyance infrastructure of the Sacramento Delta. By Aug. 31, UAVSAR data of ground movement along the San Pablo Bay shoreline were in the hands of the California Department of Water Resources, who used it to assess levee and aqueduct damage in support of their emergency response activities. It was also provided to the United States Geological Survey to direct their ground survey crews.

"NASA's UAVSAR radar imagery of the magnitude 6.0 Napa earthquake is being widely used to identify fault slip across the full Napa fault zone for the scientific, engineering and damage assessment communities and may result in the most comprehensive fault map ever produced for an earthquake in the United States," said Gerald Bawden, program scientist at NASA Headquarters, Washington.

JPL scientists, in collaboration with the Italian Space Agency's (ASI) Center for the Interpretation of Earth Observation Data and the Universita degli studi della Basilicata, also analyzed interferometric synthetic aperture radar images from ASI's COSMO-SkyMed satellites to calculate a map of the deformation of Earth's surface caused by the quake. The deformation is shown in a new false-color map that has been combined with shaded relief topography in gray. A pair of new maps created from these data can be viewed at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=pia18798

The colors in the top map indicate the amount of permanent surface movement that occurred almost entirely due to the quake, as viewed by the satellite, during a one-month interval between two COSMO-SkyMed images acquired on July 26 and Aug. 27, 2014. Scientists use these maps to build detailed models of the fault and associated land movements to better understand the impact on future earthquake activity.

The second radar map is based on the same data as the first map, but highlights very small-scale ground deformation and evidence of the fault rupture visible on Earth's surface. The inset map shows a close-up of the color cycles, revealing a discontinuity in the color cycles that identifies a potential fault rupture cutting through the Napa County Airport. United States Geological Survey and California Geological Survey field crews investigated this feature and were able to verify that the fault did break Earth's surface at this location, along a previously unidentified fault rupture.

The full COSMO-SkyMed interferogram was processed by the NASA JPL-Caltech Advanced Rapid Imaging and Analysis (ARIA) team as part of a joint collaboration between JPL; the California Institute of Technology, Pasadena; ASI's Centro Interpretazione Dati di Osservazione della Terra (CIDOT); and the Universita degli Studi della Basilicata.

The rapid response data maps developed under NASA's E-DECIDER (Emergency Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response) disaster decision support system were provided to the California Earthquake Clearinghouse to help decision makers direct response efforts. The E-DECIDER products may be viewed at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18797

They include an aftershock forecast map that highlights where aftershocks are likely to occur; a strain magnitude map that highlights areas where the greatest ground deformation has occurred based on a fault model; and InLET (Internet Loss Estimation Tool), which provides immediate post-event estimates of casualties and building damage for planning purposes and early response after an earthquake before more detailed data become available.

For more on the UAVSAR Napa earthquake studies, visit:

http://www.jpl.nasa.gov/news/news.php?release=2014-293

The NASA UAVSAR project serves as a technology and applications testbed for a NASA spaceborne L-band synthetic aperture radar mission now under formulation. When launched, this mission would extend the UAVSAR regional capability to a global scope. More information on this mission can be found at:

http://nisar.jpl.nasa.gov

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA's Earth science activities in 2014, visit:

http://www.nasa.gov/earthrightnow

Alan Buis

Jet Propulsion Laboratory, Pasadena, California

818-354-0474

alan.buis@jpl.nasa.gov


2014-306
Posted by Nelio Inacio at 9:27 AM 0 comments

NEWS : First Map of Rosetta's Comet

First Map of Rosetta's Comet:

Distinct Terrains on Rosetta's Comet
This view of the "belly" and part of the "head" of comet 67P/Churyumov-Gerasimenko indicates several morphologically different regions. Image credit: ESA/Rosetta/MPS for OSIRIS Team/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

› Full image and caption


September 11, 2014

Scientists have found that the surface of comet 67P/Churyumov-Gerasimenko -- the target of study for the European Space Agency's Rosetta mission -- can be divided into several regions, each characterized by different classes of features. High-resolution images of the comet reveal a unique, multifaceted world.

ESA's Rosetta spacecraft arrived at its destination about a month ago and is currently accompanying the comet as it progresses on its route toward the inner solar system. Scientists have analyzed images of the comet's surface taken by OSIRIS, Rosetta's scientific imaging system, and defined several different regions, each of which has a distinctive physical appearance. This analysis provides the basis for a detailed scientific description of 67P's surface. A map showing the comet's various regions is available at:

http://go.nasa.gov/1pU26L2

"Never before have we seen a cometary surface in such detail," says OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Science (MPS) in Germany. In some of the images, one pixel corresponds to a scale of 30 inches (75 centimeters) on the nucleus. "It is a historic moment -- we have an unprecedented resolution to map a comet," he says.

The comet has areas dominated by cliffs, depressions, craters, boulders and even parallel grooves. While some of these areas appear to be quiet, others seem to be shaped by the comet's activity, in which grains emitted from below the surface fall back to the ground in the nearby area.

"This first map is, of course, only the beginning of our work," says Sierks. "At this point, nobody truly understands how the surface variations we are currently witnessing came to be."

As both comet 67P and Rosetta travel closer to the sun during the next few months, the OSIRIS team and other instruments on the payload will monitor the surface to look for changes. While scientists do not expect the borderlines they have identified for the comet's different regions to vary dramatically, even subtle transformations of the surface may help to explain how cometary activity created such a breathtaking world.

The new comet maps will offer valuable insights for members of the Rosetta team, who plan to gather in Toulouse, France, on September 13 and 14, to determine a primary and backup landing site from five candidates they previously had selected.

The scientific imaging system, OSIRIS, was built by a consortium led by the Max Planck Institute for Solar System Research (Germany) in collaboration with Center of Studies and Activities for Space, University of Padua (Italy), the Astrophysical Laboratory of Marseille (France), the Institute of Astrophysics of Andalusia, CSIC (Spain), the Scientific Support Office of the European Space Agency (Netherlands), the National Institute for Aerospace Technology (Spain), the Technical University of Madrid (Spain), the Department of Physics and Astronomy of Uppsala University (Sweden) and the Institute of Computer and Network Engineering of the TU Braunschweig (Germany). OSIRIS was financially supported by the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain, and Sweden and the ESA Technical Directorate.

Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta will be the first mission in history to rendezvous with a comet, escort it as it orbits the sun, and deploy a lander to its surface.

For more information on the U.S. instruments aboard Rosetta, visit:

http://rosetta.jpl.nasa.gov

More information about Rosetta is available at:

http://www.esa.int/rosetta

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

818-393-9011

agle@jpl.nasa.gov


2014-308
Posted by Nelio Inacio at 9:27 AM 0 comments

Sunday, September 7, 2014

A New Marker Might Better Track the Solar Cycle

A New Marker Might Better Track the Solar Cycle:



This image from the Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet Imaging Telescope (EIT) image shows large magnetically active regions and a pair of curving erupting prominences on June 28, 2000 during the current solar cycle 23 maximum. Prominences are huge clouds of relatively cool dense plasma suspended in the Sun's hot, thin corona. Magnetically active regions cause the principal total solar irradiance variations during each solar cycle. The hottest areas appear almost white, while the darker red areas indicate cooler temperatures. Credit: NASA & European Space Agency (ESA)

This image from the Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet Imaging Telescope (EIT) shows large magnetically active regions and a pair of curving erupting prominences on June 28, 2000 during the solar cycle 23 maximum. Credit: NASA & European Space Agency (ESA)
Approximately every 11 years the Sun becomes violently active, putting on a show of magnetic activity for aurora watchers and sungazers alike. But the timing of the solar cycle is far from precise, making it hard to determine the exact underlying physics.

Typically astronomers use sunspots to map the course of the solar cycle, but now an international team of astronomers have discovered a new marker: brightpoints, small bright spots in the solar atmosphere that allow us to observe the constant turmoil of material inside the Sun.

The new markers provide a new method in understanding how the Sun’s magnetic field evolves over time, suggesting a deeper and longer cycle.

A well-behaved Sun flips its north and south magnetic poles every 11 years. The cycle begins when the field is weak and dipolar. But the Sun’s rotation is faster at its equator than at its poles, and this difference stretches and tangles the magnetic field lines, ultimately producing sunspots, prominences, and sometimes flares.

“Sunspots have been the perennial marker for understanding the mechanisms that rule the sun’s interior,” said lead author Scott McIntosh, from the National Center for Atmospheric Research, in a news release. “But the processes that make sunspots are not well understood, and far less, those that govern their migration and what drives their movement.”

So McIntosh and colleagues developed a new tracking devise: spots of extreme ultraviolet and X-ray light, known as brightpoints in the Sun’s atmosphere, or corona.

“Now we can see there are bright points in the solar atmosphere, which act like buoys anchored to what’s going on much deeper down,” said McIntosh. “They help us develop a different picture of the interior of the sun.”

McIntosh and colleagues dug through the wealth of data available from the Solar and Heliospheric Observatory and the Solar Dynamics Observatory. They noticed that multiple bands of these markers also move steadily toward the equator over time. But they do so on a different timescale than sunspots.

At solar minimum there might be two bands in the northern hemisphere (one positive and one negative) and two bands in the southern hemisphere (one negative and one positive). Due to their close proximity, bands of opposite charge easily cancel one another, causing the Sun’s magnetic system to be calmer, producing fewer sunspots and eruptions.

But once the two low-latitude bands reach the equator, their polarities cancel each other out and the bands abruptly disappear — a process that takes 19 years on average.

The Sun is now left with just two large bands that have migrated to about 30 degrees latitude. Without the nearby band, the polarities don’t cancel. At this point the Sun’s calm face begins to become violently active as sunspots start to grow rapidly.

Solar maximum only lasts so long, however, because the process of generating a new band of opposite polarity has already begun at high latitudes.



In this scenario, it is the magnetic band’s cycle that truly defines the solar cycle. “Thus, the 11-year solar cycle can be viewed as the overlap between two much longer cycles,” said coauthor Robert Leamon, from Montana State University in Bozeman.

The true test, however, will come with the next solar cycle. McIntosh and colleagues predict that the Sun will enter a solar minimum somewhere in the last half of 2017, and the first sunspots of the next cycle will appear near the end of 2019.

The findings have been published in the Sept. 1 issue of the Astrophysical Journal and are available online.
Posted by Nelio Inacio at 3:51 PM 0 comments
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