vendredi 9 mars 2012

Hubble Image of Galaxies' El Dorado

NASA - Hubble Space Telescope patch.

March 9, 2012

NASA / ESA Hubble Space Telescope has produced this beautiful image of the galaxy NGC 1483. NGC 1483 is a barred spiral galaxy located in the southern constellation of Dorado — the dolphinfish (or Mahi-mahi fish) in Spanish. The nebulous galaxy features a bright central bulge and diffuse arms with distinct star-forming regions. In the background, many other distant galaxies can be seen.

The constellation Dorado is home to the Dorado Group of galaxies, a loose group comprised of an estimated 70 galaxies and located some 62 million light-years away. The Dorado group is much larger than the Local Group that includes the Milky Way (and which contains around 30 galaxies) and approaches the size of a galaxy cluster. Galaxy clusters are the largest groupings of galaxies (and indeed the largest structures of any type) in the universe to be held together by their gravity.

Barred spiral galaxies are so named because of the prominent bar-shaped structures found in their center. They form about two thirds of all spiral galaxies, including the Milky Way. Recent studies suggest that bars may be a common stage in the formation of spiral galaxies, and may indicate that a galaxy has reached full maturity.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information about Hubble visit: and

ESA Hubble site:

Image, Text, Credit: ESA / Hubble & NASA.

Best regards,

jeudi 8 mars 2012

Proba-2 sees large solar flares that threaten geomagnetic storm

ESA - PROBA-2 Mission logo / ESA / NASA - SOHO Mission patch.

8 March 2012

A pair of unusually large solar flares early yesterday generated a Coronal Mass Ejection that will reach Earth around mid-day today. It will likely cause at least a strong geomagnetic storm that could affect satellites in space and trigger auroral displays.

The effects at ground level are expected to be limited, but there is a good chance for some excellent auroral displays in the north.

Solar flare seen by Proba-2

The extra-large two solar flares occurred at 23:24 GMT on 6 March and 00:14 GMT yesterday, throwing off a huge cloud of magnetised plasma from the Sun's atmosphere – the corona – into interplanetary space.

These Coronal Mass Ejections (CMEs) often occur in association with a solar flare. 

Dramatic events spotted by ESA and NASA missions

These dramatic events were detected by the ESA/NASA SOHO and NASA SDO spaceborne solar observatories, as well as the Proba-2 microsatellite. Together with other space organisations, ESA experts are closely monitoring the storm.

The two flares followed an earlier flare, which occurred on 04:05 GMT on 5 March.

All three came from a new active region on the Sun that was first detected on 2 March.

Solar flare seen by SOHO

The plasma cloud left the Sun at an estimated 2300 km/s – unusually fast.

However, the angle combined with deceleration from the background solar wind means that it is expected to arrive some hours later than this initial estimated speed alone would indicate.

Satellites to experience increased effects

In addition, a strong stream of high-energy protons has been generated. This 'storm' of subatomic particles was created by the shock wave ahead of the CME.

"It is therefore likely that satellites orbiting Earth will experience increased radiation levels today as a result," says Juha-Pekka Luntama, Head of Space Weather in ESA’s Space Situational Awareness office.

Aurora Borealis

"Space radiation levels are expected to remain high throughout 8 March and possibly for one to two days longer."

"In addition, the arrival of the geomagnetic storm could affect systems including GPS navigation satellite signals and satellite communications."

ESA spacecraft already affected

The Venus Express spacecraft, now orbiting Venus and much closer to the Sun than Earth, was affected by the radiation on 7 March.

The startracker cameras that help Venus Express measure its position and orientation in space were ‘blinded’ starting at 01:41 GMT.

Venus Express

"The Mission Control Team has taken the startrackers out of service and is maintaining the spacecraft's attitude using gyroscopes until the solar effects fade," says Octavio Camino, Venus Express Spacecraft Operations Manager at ESA’s European Space Operations Centre in Darmstadt, Germany.

Alexi Glover, an ESA space weather scientist, says that the solar region causing the current activity has a complex magnetic configuration and is now close to the centre of the Sun's disc.

"So there is a good chance of more large events in the coming days," she notes.

More information

Media contacts plus extended information on Europe, space weather and Space Situational Awareness:

Related link:

ESA / NASA SOHO homepage:

Images, Videos, Text, Credits: ESA / NASA.

Best regards,

Earth’s magnetic field provides vital protection

ESA - Cluster II Mission patch.

8 March 2012

A chance alignment of planets during a passing gust of the solar wind has allowed scientists to compare the protective effects of Earth’s magnetic field with that of Mars’ naked atmosphere. The result is clear: Earth’s magnetic field is vital for keeping our atmosphere in place.

The alignment took place on 6 January 2008. Using ESA’s Cluster and Mars Express missions to provide data from Earth and Mars, respectively, scientists compared the loss of oxygen from the two planets’ atmospheres as the same stream of solar wind hit them. This allowed a direct evaluation of the effectiveness of Earth’s magnetic field in protecting our atmosphere.

Propagation of a solar wind stream

They found that while the pressure of the solar wind increased at each planet by similar amounts, the increase in the rate of loss of martian oxygen was ten times that of Earth’s increase.

Such a difference would have a dramatic impact over billions of years, leading to large losses of the martian atmosphere, perhaps explaining or at least contributing to its current tenuous state. 

The result proves the efficacy of Earth’s magnetic field in deflecting the solar wind and protecting our atmosphere.

Artist's impression of Mars’ magnetosphere

“The shielding effect of the magnetic field is easy to understand and to prove in computer simulations, thus it has become the default explanation,” says Yong Wei from the Max-Planck-Institut für Sonnensystemforschung, Germany, who led the study.

Now, by making measurements during a planetary alignment when the two planets were being hit by exactly the same part of the solar wind, the team have proved it in reality.

They now hope to extend their work by incorporating data from ESA’s Venus Express spacecraft, which also carries a sensor that can measure the loss of its atmosphere.

Venus will provide an important new perspective on the issue because like Mars, it has no global magnetic field, yet it is similar in size to Earth and has a much thicker atmosphere.

It will therefore provide unique data to help place the Earth and Mars results in context.

There are a number of upcoming planetary alignments that will provide good opportunities for such studies.

Artist’s impression of Venus, Earth and Mars interacting with the solar wind

“For the next few months there is a good alignment between the Sun, Earth, Venus and Mars, and observations made by many spacecraft, including Mars Express, Venus Express and NASA’s STEREO solar observatory, will be analysed together,” says Olivier Witasse, ESA Mars Express Project Scientist.

Cluster will continue to play an important role in these studies, too. It is the only mission in near-Earth space capable of taking such measurements.

In addition, scientists are keen to observe how the increase in solar activity associated with the current solar cycle may affect the loss of atmospheric particles from all three planets.

“The European family of Solar System missions, with their unique observational capabilities, will play a vital role in studying this behaviour during the approaching maximum in solar activity,” says Matt Taylor, ESA Cluster Project Scientist.

Related links:

Exploring the Sun-Earth connection:

Space Operations & Situational Awareness:

Cluster overview:

Cluster II operations:

In depth:

Cluster reveals Earth's bow shock is remarkably thin:

Images, Animation, Text, Credits: ESA.


mercredi 7 mars 2012

CERN experiment makes spectroscopic measurement of antihydrogen

CERN - European Organization for Nuclear Research logo.

March 7, 2012

Image above: Electrodes for the ALPHA Penning trap are inserted into the vacuum chamber and cryostat assembly. Positrons and antiprotons combine in the trap to form antihydrogen (Image: Niels Madsen ALPHA / Swansea).

In a paper published online today by the journal Nature, the ALPHA collaboration at CERN reports an important milestone on the way to measuring the properties of antimatter atoms. This follows news reported in June last year that the collaboration had routinely trapped antihydrogen atoms for long periods of time. ALPHA’s latest advance is the next important milestone on the way to being able to make precision comparisons between atoms of ordinary matter and atoms of antimatter, thereby helping to unravel one of the deepest mysteries in particle physics and perhaps understanding why a Universe of matter exists at all.

ALPHA experiment animation


CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 20 Member States.

Find out more:

    CERN press release:

    ALPHA website:

    CERN news:

    B-roll & interview:



    ALPHA spokesperson Jeffrey Hangst:

    The ALPHA facility:

    The Antiproton Decelerator:

Image (mentioned), Animation, Text, Credit: CERN.


NASA Mars Orbiter Catches Twister in Action

NASA - Mars Reconnaissance Orbiter (MRO) patch.


A towering dust devil, casts a serpentine shadow over the Martian surface in this image acquired by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Image Credit: NASA / JPL-Caltech / Univ. of Arizona.

An afternoon whirlwind on Mars lofts a twisting column of dust more than half a mile (800 meters) high in an image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

HiRISE captured the image on Feb. 16, 2012, while the orbiter passed over the Amazonis Planitia region of northern Mars. In the area observed, paths of many previous whirlwinds, or dust devils, are visible as streaks on the dusty surface.

The active dust devil displays a delicate arc produced by a westerly breeze partway up its height. The dust plume is about 30 yards or meters in diameter.

Artists impression of MRO orbiting Mars. Credit: NASA

The image was taken during the time of Martian year when that planet is farthest from the sun. Just as on Earth, winds on Mars are powered by solar heating. Exposure to the sun's rays declines during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.

Dust devils occur on Earth as well as on Mars. They are spinning columns of air, made visible by the dust they pull off the ground. Unlike a tornado, a dust devil typically forms on a clear day when the ground is heated by the sun, warming the air just above the ground. As heated air near the surface rises quickly through a small pocket of cooler air above it, the air may begin to rotate, if conditions are just right.

The Mars Reconnaissance Orbiter has been examining Mars with six science instruments since 2006. Now in an extended mission, the orbiter continues to provide insights into the planet's ancient environments and how processes such as wind, meteorite impacts and seasonal frosts continue to affect the Martian surface today. This mission has returned more data about Mars than all other orbital and surface missions combined.

More than 21,700 images taken by HiRISE are available for viewing on the instrument team's website: . Each observation by this telescopic camera covers several square miles, or square kilometers, and can reveal features as small as a desk.

HiRISE is operated by the University of Arizona, Tucson. The instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo. The Mars Reconnaissance Orbiter Project and the Mars Exploration Rover Project are managed by the Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology, also in Pasadena. Lockheed Martin Space Systems, Denver, built the orbiter. For more information about the Mars Reconnaissance Orbiter, see .

Images, Text, Credit: NASA / JPL / Guy Webster.


NASA's Twin GRAIL Spacecraft Begin Collecting Lunar Science Data

NASA - GRAIL Mission patch.


NASA's Gravity Recovery And Interior Laboratory (GRAIL) spacecraft orbiting the moon officially have begun their science collection phase. During the next 84 days, scientists will obtain a high-resolution map of the lunar gravitational field to learn about the moon's internal structure and composition in unprecedented detail. The data also will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

"The initiation of science data collection is a time when the team lets out a collective sigh of relief because we are finally doing what we came to do," said Maria Zuber, principal investigator for the GRAIL mission at the Massachusetts Institute of Technology in Cambridge, "but it is also a time where we have to put the coffee pot on, roll up our sleeves and get to work."

Artist concept of GRAIL mission. GRAIL will fly twin spacecraft in tandem orbits around the moon to measure its gravity field in unprecedented detail. Image credit: NASA/JPL.

The GRAIL mission's twin, washing-machine-sized spacecraft, named Ebb and Flow, entered lunar orbit on New Year's Eve and New Years Day. GRAIL's science phase began yesterday at 5:15 p.m. PST (8:15 p.m. EST). During this mission phase, the spacecraft will transmit radio signals precisely defining the rate of change of distance between the two. The distance between the spacecraft will change slightly as they fly over areas of greater and lesser gravity caused by visible features such as mountains, craters and masses hidden beneath the lunar surface. Science activities are expected to conclude on May 29, after GRAIL maps the gravity field of the moon three times.

"We are in a near-polar, near-circular orbit with an average altitude of about 34 miles (55 kilometers) right now," said David Lehman, GRAIL project manager from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "During the science phase, our spacecraft will orbit the moon as high as 31 miles (51 kilometers) and as low as 10 miles (16 kilometers). They will get as close to each other as 40 miles (65 kilometers) and as far apart as 140 miles (225 kilometers)."

The two spacecraft were previously named GRAIL A and B. The names Ebb and Flow were the result of a nationwide student contest to choose new names for them. The winning entry was submitted by fourth graders from the Emily Dickinson Elementary School in Bozeman, Mont. Nearly 900 classrooms with more than 11,000 students from 45 states, Puerto Rico and the District of Columbia, participated in the contest.

JPL manages the GRAIL mission for NASA's Science Mission Directorate in Washington. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft.

For more information about GRAIL, visit: .

Image (mentioned), Text, Credits: NASA / DC Agle / JPL / Dwayne Brown / Caroline McCall / MIT.


Galaxies Get Up Close and Personal

ESO - European Southern Observatory logo.

7 March 2012

VST captures collisions in young galaxy cluster

VST image of the Hercules galaxy cluster

The VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile has imaged a fascinating collection of interacting galaxies in the Hercules galaxy cluster. The sharpness of the new picture, and the hundreds of galaxies captured in great detail in less than three hours of observations, attest to the great power of the VST and its huge camera OmegaCAM to explore the nearby Universe.

Highlights of the VST image of the Hercules galaxy cluster

The Hercules galaxy cluster (also known as Abell 2151) lies about 500 million light-years away in the constellation of Hercules. It is unlike other nearby galactic assemblies in many ways. As well as being rather irregular in shape, it contains a wide variety of galaxy types, particularly young, star-forming spiral galaxies, and there are no giant elliptical galaxies in sight.

The new image was taken with the VST, the most recent addition to ESO’s Paranal Observatory in Chile (eso1119). The VST is a survey telescope equipped with OmegaCAM, a 268-megapixel camera that provides images covering very large areas on the sky. Normally only small telescopes can image large objects such as this in a single shot, but the 2.6-metre VST not only has a wide field, but can also exploit the superb conditions on Paranal to simultaneously obtain very sharp and deep images quickly.

The location of the Hercules galaxy cluster

Galaxy pairs getting up close and personal and on their way to merging into single, larger galaxies can be seen all over this image. The numerous interactions, and the large number of gas-rich, star-forming spiral galaxies in the cluster, make the members of the Hercules cluster look like the young galaxies of the more distant Universe [1]. Because of this similarity, astronomers believe that the Hercules galaxy cluster is a relatively young cluster. It is a vibrant and dynamic swarm of galaxies that will one day mature into one more similar to the older galaxy clusters that are more typical of our galactic neighbourhood.

Wide-field view of the Hercules galaxy cluster

Galaxy clusters are formed when smaller groups of galaxies come together due to the pull of their gravity. As these groups get closer to each other, the cluster becomes more compact and more spherical in shape. At the same time, the galaxies themselves get closer together and many start to interact. Even if spiral galaxies are dominant in the initial groups, the galactic collisions eventually distort their spiral structure and strip off their gas and dust, quenching most star formation. For this reason, most of the galaxies in a mature cluster are elliptical or irregular in shape. One or two large elliptical galaxies, formed from the merger of smaller galaxies and permeated by old stars, usually reside at the centres of these old clusters.

Zooming in on the Hercules galaxy cluster

The Hercules galaxy cluster is believed to be a collection of at least three small clusters and groups of galaxies that are currently being assembled into a larger structure. Furthermore, the cluster itself is merging with other large clusters to form a galaxy supercluster. These giant collections of clusters are some of the largest structures in the Universe. The wide field of view and image quality of OmegaCAM on the VST make it ideal for studying the outskirts of galaxy clusters where the poorly-understood interactions between clusters are taking place.

Panning across on the Hercules galaxy cluster

This beautiful image shows not only the galaxies of the Hercules galaxy cluster, but also many faint and fuzzy objects in the background, which are galaxies that are much further away from us. Closer to home, several brilliant Milky Way stars are also visible in the foreground and there are even a few asteroids that have left short trails as they moved slowly across the image during the exposures.


[1] Objects in the very distant Universe are seen as they were when much younger, because it takes several billion years for their light to reach us.

More information:

The VST programme is a joint venture between the INAF–Osservatorio Astronomico di Capodimonte, Naples, Italy and ESO. INAF designed and built the telescope with the collaboration of leading Italian industries and ESO was responsible for the enclosure and the civil engineering works at the site. OmegaCAM, the VST’s camera, was designed and built by a consortium including institutes in the Netherlands, Germany and Italy with major contributions from ESO. The facility is operated by ESO, which also archives and distributes data from the telescope.

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.


    Photos of VST:

    Photos of OmegaCAM:

Images, Text, Credits: ESO / Richard Hook / INAF-VST / OmegaCAM. Acknowledgement: OmegaCen / Astro-WISE/Kapteyn Institute / Videos: ESO / INAF-VST / OmegaCAM / A. Fujii / Digitized Sky Survey 2. Music: John Dyson (from the album Moonwind).

Best regards,

lundi 5 mars 2012

Observation Data of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard ISS

JAXA - Kibo Japanese Experiment Module patch,

March 5, 2012 (JST)

Public Release of Observation Data of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard Japanese Experiment Module “KIBO” on the International Space Station.

The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) implemented Earth’s atmosphere observation mission with unprecedented high-precision, owing to the superconducting detector cooled down to 4K (-269 deg C). SMILES was developed under cooperation between Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT), and it had been attached to the Japanese Experiment Module “KIBO” onboard the International Space Station.

JAXA and NICT have been carrying on improvement of retrieval of atmospheric minor constituents in order to demonstrate high performance of SMILES instrument and have been distributing level-2 observation data limited to the selected research groups among all applicants to the SMILES Research Announcement in August of 2009.

This time, we would like to release the SMILES observation data to the public, as we confirmed the high precision of these data. The data released to the public are the altitude distribution of 11 types of atmospheric minor constituents including ozone and chlorine compounds, retrieved from brightness temperature of 625-650 GHz electromagnetic emission measured by SMILES instrument. These data explain chemical phenomena of atmospheric minor constituents in stratosphere and lower mesosphere, therefore they contribute to the comprehensive analysis of Earth’s climate change including stratospheric ozone variation (such as “Ozone hole problem”) and global warming issues.

Image above: A sample of global distribution of atmospheric minor constituents (ozone) with processing the data in this public release.

SMILES: website for data release:

* To whom wish to download these data, we request to register on this website. Please send e-mail to with description of your name, affiliation and objectives for utilizing those data (around 50 words). We will reply to your application with some information how to download the data.


SMILES is an atmospheric observation sensor for measuring weak sub-millimeter wave emitted from atmospheric minor constituents with cryogenically-cooled superconducting detector. The superconducting detector can suppress its thermal noise to ultimate low levels, which improves its measurement performance. Compared with the existing spaceborne instruments without using superconducting detectors, SMILES revealed as one-digit higher performance than that of those instruments. As a result, SMILES carried out precise observation of minor constituents which were difficult to detect using previous instruments. SMILES was attached to the Exposed Facility of “KIBO” module in September 2009, and soon its operation started. SMILES acquired 6-month observation data of Earth’s atmosphere till its malfunction of the oscillator component inside the instrument in April 2010.

Screen shot of SMILES website for data release (

 The simplest sample of schematization with individual unit of SMILES data

Sample: Altitudinal profile of concentration of chlorine compounds (ClO)

This profile shows an observation sample over latitude 32 degree north and longitude 140 degree east. H-shaped horizontal lines mean errors of concentration at each altitude. (Short lines mean low errors, that is high precision.) A blue line (SMILES data) shows lower errors than a red dashed line (observation data near this point with the American earth observation satellite). Looking at distribution itself, the blue line shows mound-shaped distribution compared with the zigzag red line, so SMILES seems to capture the chemical process of atmosphere with higher precision.

Global distribution with processing released SMILES data

(Click on the image for enlarge)

Stratospheric ozone depletion and variation of related chlorine compounds in high latitude region in the northern hemisphere, which was observed on January 28, 2010.

This figure show a sample of observation from over east coast of Canada to China via northern Europe (upper right panel). Remaining three panels show the vertical distribution of concentration of ozone, ClO and HCl respectively.

    Upper left: It is pictured that ozone volume is lowered (dark blue) than the surrounding area (light blue) at altitude 20-25 km in latitude 60-65 deg N and longitude 20-55 deg E (over Europe).

    Lower left: Chlorine compounds chemically destroying ozone (ClO) are enhanced (light blue, yellow and red) than the surrounding area (dark blue) in the same region and altitude.

    Lower right: Chlorine compounds keeping chlorine atoms on stable state (HCl) are lowered (dark blue) than the surrounding area (red and yellow) in the same region and altitude.

    Upper right: This shows SMILES observation points where the data were obtained for drawing above three figures. The points surrounded with a purple circle show the region where ozone and chlorine compounds vary compared with the circumference.

Specifications of the Data for Public Release

Related Links: (Status of SMILES; including the first light on October 2009) (Official website for SMILES mission) (International Space Station in JAXA website) (SMILES website in NICT) (Quick look webpage for NICT research data product, *members-only service)

Images, Graphic, Text, Credit: Japan Aerospace Exploration Agency (JAXA) / National Institute of Information and Communications Technology (NICT).


Solar flare pushes plasma cloud toward Earth

NASA / ESA - SOHO Mission patch.

5 March 2012

A large solar flare erupted from the Sun earlier today, launching a coronal mass ejection (CME) into space. This plasma 'cloud' is expected to pass Earth in 2 to 3 days, potentially causing increased nighttime auroras. No major effects on Earth are expected.

The solar flare occurred at about 05:05 CET today, and the resulting CME was detected by the Large Angle and Spectrometric Coronagraph (LASCO) instrument on board the ESA/NASA Solar & Heliospheric Observatory (SOHO) mission.

The solar flare was categorised by scientists as an 'X-class' flare; these are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms.

A solar flare seen by the joint ESA/NASA SOHO mission, which reached its peak at about 04:13 UT on 5 March 2012. The flare caused a Coronal Mass Ejection (CME), which was ejected toward Earth.

If a CME is associated with a flare, the arrival of the CME at Earth can trigger a geomagnetic storm. For the CME detected this morning, which is expected to arrive around 7 or 8 March, no major geomagnetic impacts are expected due to the angle of approach of the cloud of plasma particles toward the Earth. 

"We had another significant solar event early this morning. While an X-flare is considered 'large,' the geomagnetic impact is expected to be only minor to moderate, as the travelling CME is expected to mostly miss the Earth," said Juha-Pekka Luntama, Head of Space Weather at ESA's Space Situational Awareness programme office.

"In fact, there is already some increase in the flow of energetic particles from the Sun toward the Earth due to an earlier, but smaller 'M-class', solar flare; both these are part of a continuing trend of increased solar activity."

It is important to monitor, track and assess space weather events such as solar flares.

Such events are more than capable of affecting space-based telecommunications, broadcasting, weather services and navigation through to power distribution and terrestrial communications, especially at northern latitudes.

For more information, visit:  and

Animation, Text, Credits: ESA / NASA.


dimanche 4 mars 2012

Cassini Detects Hint of Fresh Air at Dione

NASA / ESA - Cassini "Insider's" logo.

March 4, 2012

NASA's Cassini spacecraft has "sniffed" molecular oxygen ions around Saturn's icy moon Dione for the first time, confirming the presence of a very tenuous atmosphere. The oxygen ions are quite sparse – one for every 0.67 cubic inches of space (one for every 11 cubic centimeters of space) or about 2,550 per cubic foot (90,000 per cubic meter) – show that Dione has an extremely thin neutral atmosphere.

At the Dione surface, this atmosphere would only be as dense as Earth's atmosphere 300 miles (480 kilometers) above the surface. The detection of this faint atmosphere, known as an exosphere, is described in a recent issue of the journal Geophysical Research Letters.

This view highlights tectonic faults and craters on Dione, an icy world that has undoubtedly experienced geologic activity since its formation. Image credit: NASA/JPL/Space Science Institute.

"We now know that Dione, in addition to Saturn's rings and the moon Rhea, is a source of oxygen molecules," said Robert Tokar, a Cassini team member based at Los Alamos National Laboratory, Los Alamos, N.M., and the lead author of the paper. "This shows that molecular oxygen is actually common in the Saturn system and reinforces that it can come from a process that doesn't involve life."

Dione's oxygen appears to derive from either solar photons or energetic particles from space bombarding the moon's water ice surface and liberating oxygen molecules, Tokar said. But scientists will be looking for other processes, including geological ones, that could also explain the oxygen.

"Scientists weren't even sure Dione would be big enough to hang on to an exosphere, but this new research shows that Dione is even more interesting than we previously thought," said Amanda Hendrix, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not directly involved in the study. "Scientists are now digging through Cassini data on Dione to look at this moon in more detail."

Several solid solar system bodies – including Earth, Venus, Mars and Saturn's largest moon Titan – have atmospheres. But they tend to be typically much denser than what has been found around Dione. However, Cassini scientists did detect a thin exosphere around Saturn's moon Rhea in 2010, very similar to Dione. The density of oxygen at the surfaces of Dione and Rhea is around 5 trillion times less dense than that at Earth's surface.

Tokar said scientists suspected molecular oxygen would exist at Dione because NASA's Hubble Space Telescope detected ozone. But they didn't know for sure until Cassini was able to measure ionized molecular oxygen on its second flyby of Dione on April 7, 2010 with the Cassini plasma spectrometer. On that flyby, the spacecraft flew within about 313 miles (503 kilometers) of the moon's surface.

Cassini scientists are also analyzing data from Cassini's ion and neutral mass spectrometer from a very close flyby on Dec. 12, 2011. The ion and neutral mass spectrometer made the detection of Rhea's thin atmosphere, so scientists will be able to compare Cassini data from the two moons and see if there are other molecules in Dione's exosphere.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The Cassini plasma spectrometer team and the ion and neutral mass spectrometer team are based at Southwest Research Institute, San Antonio.

For more information about the mission, visit: and or

Image (mentioned), Text, Credit: NASA / JPL / Jia-Rui C. Cook.

Best regards,