18
Dec 10

Total lunar eclipse is coming on December 21st

Very early in the morning of December 21st, Europe will see the Moon's appearance change due to a total lunar eclipse. The Moon will become colourful from bright orange to blood red to dark brown and perhaps gray. The total lunar eclipse will begin when the moon moves into Earth's penumbral shadow on December 21st, 2010 at 5h29min (UTC).

This eclipse's maximum will occur at 08h17min (UTC) which means it will be early in the morning and that it will be visible at moonset in most western Europe. In America it will occur in the middle of the night and the Moon will be high above the horizon. The eclipse occurs as the moon passes through the northern portion of Earth's shadow, just four days before perigee, when the moon is closest to Earth.

The Lunar Eclipse of December 21st.
Image credit: Tom Ruen / Wikipedia

The EAAE's project Moonwalkers brings a new  challenge to school teachers and to all educators in general. Students and teachers are invited to share every kind of observations of the Moon that make and we will present your reports pictures or drawings on our webpage with due credit.


Lunar Eclipse - September 2007

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17
Dec 10

NASA Discovers Asteroid Delivered Assortment of Meteorites

Source: NASA


Image credit: Andreus / Dreamstime.com.

An international team of scientists studying remnants of an asteroid that crashed into the Nubian Desert in October 2008 discovered it contained at least 10 different types of meteorites. Some of them contained chemicals that form the building blocks of life on Earth, and those chemicals were spread through all parts of the asteroid by collisions.

Chemists at Stanford University found that different meteorite types share the same distinct fingerprint of polycyclic aromatic hydrocarbons (PAHs). These complex organic molecules are distributed throughout the galaxy and form on Earth from incomplete combustion.

A research team from NASA's Goddard Space Flight Center in Greenbelt, Md., found amino acids in strongly heated fragments of the asteroid, where all such molecules should have been destroyed. Both PAHs and amino acids are considered building blocks of life.

Before landing on Earth, the 13-foot asteroid was detected by a telescope from the NASA-sponsored Catalina Sky Survey based at the University of Arizona in Tucson. Hours prior to its demise, astronomers and scientists around the world tracked and scanned the asteroid. It was the first time a celestial object was observed prior to entering Earth's atmosphere.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., created a search grid and impact target area. The data helped Peter Jenniskens, an astronomer at NASA's Ames Research Center in Moffett Field, Calif., and the SETI Institute of Mountain View, Calif., guide a recovery team from the University of Khartoum in Sudan to search the desert landscape. During four expeditions, approximately 150 students recovered nearly 600 meteorite fragments weighing a total of more than 23 pounds.

"Right from the start, the students were surprised to find so much diversity in meteorite texture and hue," said Muawia Shaddad, an astronomer at the University of Khartoum, who led the search effort. "We estimate the asteroid initially weighed about 59 tons, of which about 86 pounds survived the explosion high in the atmosphere."

Subsequently, scientists determined most of the fragments are a rare type of meteorite called ureilites. Less than 10 of the nearly 1,000 known meteorites are ureilites. The recovery team made history when they found the first-ever freshly fallen mixed-composition, or polymict ureilite. The majority of the remaining fragments are similar to the more common types of meteorites called chondrites.

Other Ames researchers showed the ureilite fragments contained widely varying amounts of the minerals called olivine and pyroxene. Carnegie Institute of Washington researchers found these minerals have the full range of oxygen atom signatures detected in previous ureilites. Scientists believe this is evidence all ureilites originated from the same source, called the ureilite parent body. Astronomers theorize the parent body experienced a giant collision approximately 4.5 billion years ago and caused iron-rich minerals to smelt into metallic iron. However, the olivine and pyroxene didn't melt, which allowed the oxygen atoms in them to stay in the same arrangement as when they first formed.

Researchers at NASA's Johnson Space Center in Houston were able to deduce that much of the ureilite parent body was reduced to fragments measuring 30 to 300 feet during this giant collision. After the catastrophic collision, scientists believe the material that ended up making 2008 TC3 had a long history of violent collisions and impacts. These later collisions ground the fragments down into the smaller sand grain-sized pieces that gathered loosely together with many voids.

Researchers believe the amino acids were delivered to 2008 TC3 during the later impacts, or formed directly from trapped gases as the asteroid cooled following the giant collision. Other non-ureilite types of meteorites also became part of the asteroid. To date, ten different meteorite types have been identified, accounting for 20-30 percent of the asteroid's recovered remains.

"Asteroids have just become a lot more interesting," Jenniskens said. "We were surprised to find that not all of the meteorites we recovered were the same, even though we are certain they came from the same asteroid."

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17
Dec 10

Space Telescope European coordinating facility closes after 26 successful years

Source: ESA/Hubble Space Telescope

The Space Telescope European Coordinating Facility, a unique collaboration between the European Space Agency (ESA) and the European Southern Observatory, will close on 31 December 2010 after 26 years. ESA’s continuing partnership with NASA on the Hubble mission ensures that European astronomers will continue to have access to observing time.

The Space Telescope European Coordinating Facility (ST-ECF), the scientific and technical co-ordination centre for the Hubble Space Telescope in Europe, will close its doors at the end of December 2010. This is part of a process in which the European Space Agency is streamlining its operations and concentrating astronomical operations, archiving and data reduction expertise at its European Space Astronomy Centre (ESAC) in Spain.

The ST-ECF was formed in 1984, six years before Hubble’s launch, as a key plank in ESA’s partnership with NASA and as a vital element in maximising Europe’s scientific return in the pre-internet age. Rather than simply contribute to Hubble science and technology programmes in the US, ESA made the strategic decision to build capabilities in Europe. As a result, the ST-ECF was formed as a joint venture between ESA and the European Southern Observatory (ESO), combining the technical and scientific expertise of both organisations.

The ST-ECF’s primary function has been as a support facility, both by contributing to the Hubble project and providing expertise and advice to European astronomers using Hubble. But this work has also had knock-on benefits elsewhere. ESO Director General, Tim de Zeeuw explains: “Establishing the ST-ECF within ESO allowed a very productive cross-fertilisation of ideas to take place. For example, the ST-ECF’s work on software, imaging and data archives have fed back into NASA’s work on Hubble. Conversely, the experience of being involved in Hubble gave ESO invaluable expertise for our Very Large Telescope.”

One area where the ST-ECF has made a particular impact is in astronomical image processing. In the early days, techniques were developed to counteract the effects of Hubble’s flawed mirror (deconvolution). This work subsequently evolved, in collaboration with NASA’s Space Telescope Science Institute (STScI), to use a combination of multiple, slightly displaced exposures (dithering) with a combination technique (drizzling) to greatly improve the imaging capability of the telescope. This work has proved very productive for astronomy in general, not just for Hubble.

In addition, staff at the ST-ECF made important advances in the modelling of the performance of various astronomical instruments. This theoretical knowledge lets astronomers create highly sophisticated computer simulations of the instruments, allowing for precise calibration of observations and more accurate results. This modelling work has provided substantial improvements in the scientific data produced by Hubble over the years.

The ST-ECF was also a pioneer of the early internet. Communication and co-ordination with NASA in the US and sharing data with astronomers across Europe meant that effective computer networking was key. To this end, the facility pioneered online access to scientific data archives, and set up one of the very first websites in Europe in the summer of 1993.

In the last few years, the ST-ECF has developed sophisticated software to exploit a capability that enables Hubble’s cameras to be used for the simultaneous spectroscopy of many sources in the field of view. Applied from a telescope in space this slitless spectroscopy is an enormously powerful technique to study the motions and properties of objects that are so faint that they cannot be reached in any other way.

A separate and very important contribution of the ST-ECF to the ESA Science Programme over many years has been its responsibility for developing communications and outreach in Europe for Hubble.

While the ST-ECF’s closure marks the end for one aspect of Hubble activities in Europe, ESA remains a firm partner to NASA in the space telescope’s continuing mission. To this end, ESA’s Science Programme Committee recently voted unanimously to extend the ESA contribution to the end of 2014, with a further extension possible.

Martin Kessler, head of ESA’s science operations department said: “European astronomers will have access to ESA’s share of observing time for as long as Hubble remains in the sky. Additionally, we expect to preserve access to Hubble data via the European Space Astronomy Centre. As part of the ongoing collaboration with NASA, ESA will continue to deploy staff based at the Space Telescope Science Institute in Baltimore, USA.”

ESO will continue to support the ESA public outreach effort for Hubble, processing images for public release, running the ESA/Hubble website at www.spacetelescope.org and producing the popular Hubblecast podcast series.

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17
Dec 10

Zooniverse lauches PlanetHunters project

Source: Planet Hunters


Screenshot of Planet Hunters website

Ever dreamed of being the first to make a discovery? Want to find a planet of your own? Thanks to http://www.planethunters.org, the latest Zooniverse project, you might just be able to, using data from NASA's Kepler mission. Kepler's goal is to catch the slight dip in brightness that's caused by a planet passing in front of its parent star.

NASA's Kepler spacecraft is one of the most powerful tools in the hunt for extrasolar planets. The Kepler Team computers are sifting through the data, but we at Planet Hunters are betting that there will be planets which can only be found via the remarkable human ability for pattern recognition.

The Kepler Team computers are sifting through the data, but we at Planet Hunters are betting that there will be planets which can only be found via the remarkable human ability for pattern recognition. This is a gamble, a bet, if you will, on the ability of humans to beat machines just occasionally - and for us to have a chance we need your help. Fancy giving it a try? If you do, you could be the first to spot an new planet – it may be a Jupiter-size behemoth or even an Earth-sized rock.  (go to PlanetHunters Project)

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17
Dec 10

Building Blocks of Life Created in "Impossible" Place

Source: NASA


Hubble Space Telescope picture of what was first thought to be a comet but is probably an asteroid collision.

NASA-funded scientists have discovered amino acids, a fundamental building block of life, in a meteorite where none were expected.

"This meteorite formed when two asteroids collided," said Dr. Daniel Glavin of NASA’s Goddard Space Flight Center, Greenbelt, Md. "The shock of the collision heated it to more than 2,000 degrees Fahrenheit, hot enough that all complex organic molecules like amino acids should have been destroyed, but we found them anyway." Glavin is lead author of a paper on this discovery appearing December 15 in Meteoritics and Planetary Science. "Finding them in this type of meteorite suggests that there is more than one way to make amino acids in space, which increases the chance for finding life elsewhere in the Universe."

Amino acids are used to make proteins, the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins. Previously, scientists at the Goddard Astrobiology Analytical Laboratory have found amino acids in samples of comet Wild 2 from NASA’s Stardust mission, and in various carbon-rich meteorites. Finding amino acids in these objects supports the theory that the origin of life got a boost from space - some of life’s ingredients formed in space and were delivered to Earth long ago by meteorite impacts.

When Dr. Peter Jenniskens of the SETI Institute, Mountain View, Calif., and NASA's Ames Research Center, Moffett Field, Calif., approached NASA with the suggestion to search for amino acids in the carbon-rich remnants of asteroid 2008 TC3, expectations were that nothing was to be found. Because of an unusually violent collision in the past, this asteroid's ingredients for life were a "culinary disaster" and now mostly in the form of graphite. The small asteroid, estimated at six to fifteen feet across, was the first to be detected in space prior to impact on Earth on October 7, 2008. When Jenniskens and Dr. Muawia Shaddad of the University of Khartoum recovered remnants in the Nubian Desert of northern Sudan, the remnants turned out to be the first Ureilite meteorites found in pristine condition.

A meteorite sample was divided between the Goddard lab and a lab at the Scripps Institution of Oceanography at the University of California, San Diego. "Our analyses confirm those obtained at Goddard," said Professor Jeffrey Bada of Scripps, who led the analysis there. The extremely sensitive equipment in both labs detected small amounts of 19 different amino acids in the sample, ranging from 0.5 to 149 parts per billion. The team had to be sure that the amino acids in the meteorite didn’t come from contamination by life on Earth, and they were able to do so because of the way amino acids are made. Amino acid molecules can be built in two ways that are mirror images of each other, like your hands. Life on Earth uses left-handed amino acids, and they are never mixed with right-handed ones, but the amino acids found in the meteorite had equal amounts of the left and right-handed varieties. (read more)

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16
Dec 10

NASA's Mars Odyssey Spacecraft Sets Exploration Record on Mars

Source: NASA


Mars Odyssey and Mars. Image credit: NASA/JPL.

NASA's Mars Odyssey, which launched in 2001, will break the record Wednesday for longest-serving spacecraft at the Red Planet. The probe begins its 3,340th day in Martian orbit at 5:55 p.m. PST (8:55 p.m. EST) on Wednesday to break the record set by NASA's Mars Global Surveyor, which orbited Mars from 1997 to 2006.

Odyssey's longevity enables continued science, including the monitoring of seasonal changes on Mars from year to year and the most detailed maps ever made of most of the planet. In 2002, the spacecraft detected hydrogen just below the surface throughout Mars' high-latitude regions. The deduction that the hydrogen is in frozen water prompted NASA's Phoenix Mars Lander mission, which confirmed the theory in 2008. Odyssey also carried the first experiment sent to Mars specifically to prepare for human missions, and found radiation levels around the planet from solar flares and cosmic rays are two to three times higher than around Earth.

Odyssey also has served as a communication relay, handling most of the data sent home by Phoenix and NASA's Mars Exploration Rovers Spirit and Opportunity. Odyssey became the middle link for continuous observation of Martian weather by NASA's Mars Global Surveyor and NASA's Mars Reconnaissance Orbiter.

"Odyssey has proved itself to be a great spacecraft, but what really enables a spacecraft to reach this sort of accomplishment is the people behind it," said Gaylon McSmith, Odyssey project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This is a tribute to the whole Odyssey team."

Odyssey will support the 2012 landing of the Mars Science Laboratory and surface operations of that mission. Mars Science Laboratory, also known as the Curiosity rover, will assess whether its landing area has had environmental conditions favorable for microbial life and preserving evidence about whether life has existed there. The rover will carry the largest, most advanced set of instruments for scientific studies ever sent to the Martian surface.

"The Mars program clearly demonstrates that world-class science coupled with sound and creative engineering equals success and longevity," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington.

Other recent NASA spacecraft at Mars include the Mars Global Surveyor that began orbiting the Red Planet in 1997. The Spirit and Opportunity rovers landed on Mars in January 2004. They have been exploring for six years, far surpassing their original 90-day mission. Phoenix landed May 25, 2008, farther north than any previous spacecraft to the planet's surface. The mission's biggest surprise was the discovery of perchlorate, an oxidizing chemical on Earth that is food for some microbes, but potentially toxic for others. The solar-powered lander completed its three-month mission and kept working until sunlight waned two months later. MRO arrived at Mars in 2006 on a search for evidence that water persisted on the planet's surface for a long period of time.

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16
Dec 10

ESA makes the Sun available to everyone

Source: ESA Space Science News

New software developed by ESA makes available online to everyone, everywhere at anytime, the entire library of images from the SOHO solar and heliospheric observatory. Just download the viewer and begin exploring the Sun.


A screenshot from the program JHelioviewer, developed by ESA.
Image credits: ESA JHelioviewer Team

Helioviewer is new visualisation software that enables everyone to explore the Sun. Developed as part of the ESA/NASA Helioviewer Project, it provides a desktop program that enables users to call up images of the Sun from the past 15 years. More than a million images from SOHO can already be accessed, and new images from NASA’s Solar Dynamics Observatory are being added every day. The downloadable JHelioviewer is complemented by the website Helioviewer.org, a web-based image browser.

Helioviewer is new visualisation software that enables everyone to explore the Sun. Developed as part of the ESA/NASA Helioviewer Project, it provides a desktop program that enables users to call up images of the Sun from the past 15 years. More than a million images from SOHO can already be accessed, and new images from NASA’s Solar Dynamics Observatory are being added every day. The downloadable JHelioviewer is complemented by the website Helioviewer.org, a web-based image browser.


Another  screenshot from the program JHelioviewer, developed by ESA.
Image credits: ESA JHelioviewer Team

JHelioviewer is written in the Java programming language, hence the ‘J’ at the beginning of its name. It is open-source software, meaning that all its components are freely available so others can help to improve the program. The code can even be reused for other purposes; it is already being used for Mars data and in medical research. This is because JHelioviewer does not need to download entire datasets, which can often be huge – it can just choose enough data to stream smoothly over the Internet.  (read more)

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16
Dec 10

Hubble spots a celestial bauble

Source: ESA/Hubble


Hubble's image of SNR B0509-67.5.
Image credit:NASA, ESA, and the Hubble Heritage Team (STScI/AURA).
Acknowledgement: J. Hughes (Rutgers University)

Hubble has spotted a festive bauble of gas in our neighbouring galaxy, the Large Magellanic Cloud. Formed in the aftermath of a supernova explosion that took place four centuries ago, this sphere of gas has been snapped in a series of observations made between 2006 and 2010.

The delicate shell, photographed by the NASA/ESA Hubble Space Telescope, appears to float serenely in the depths of space, but this apparent calm hides an inner turmoil. The gaseous envelope formed as the expanding blast wave and ejected material from a supernova tore through the nearby interstellar medium. Called SNR B0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160 000 light-years from Earth.

Ripples seen in the shell’s surface may be caused either by subtle variations in the density of the ambient interstellar gas, or possibly be driven from the interior by fragments from the initial explosion. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 18 million km/h.

Astronomers have concluded that the explosion was an example of an especially energetic and bright variety of supernova. Known as Type Ia, such supernova events are thought to result when a white dwarf star in a binary system robs its partner of material, taking on more mass than it is able to handle, so that it eventually explodes.(read more)

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16
Dec 10

Light Dawns on Dark Gamma-ray Bursts

Source: ESO Science Release eso1049


Artist’s impression shows a dark gamma-ray burst in a star forming region.
Image credit: ESO/L.Calçada

Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don’t require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. (read more)

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16
Dec 10

Global Eruption Rocks the Sun

Source: NASA


Locations of key events are labeled in this extreme ultraviolet image of the sun,
obtained by the Solar Dynamics Observatory on August 1st.
White lines trace the sun's magnetic field.
Image credit: K Schrijver & A. Title

On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. Astronomers knew they had witnessed something big.

It was so big, it may have shattered old ideas about solar activity.

"The August 1st event really opened our eyes," says Karel Schrijver of Lockheed Martin’s Solar and Astrophysics Lab in Palo Alto, CA. "We see that solar storms can be global events, playing out on scales we scarcely imagined before."

For the past three months, Schrijver has been working with fellow Lockheed-Martin solar physicist Alan Title to understand what happened during the "Great Eruption." They had plenty of data: The event was recorded in unprecedented detail by NASA's Solar Dynamics Observatory and twin STEREO spacecraft. With several colleagues present to offer commentary, they outlined their findings at a press conference today at the American Geophysical Union meeting in San Francisco.

Explosions on the sun are not localized or isolated events, they announced. Instead, solar activity is interconnected by magnetism over breathtaking distances. Solar flares, tsunamis, coronal mass ejections--they can go off all at once, hundreds of thousands of miles apart, in a dizzyingly-complex concert of violence.

"To predict eruptions we can no longer focus on the magnetic fields of isolated active regions," says Title, "we have to know the surface magnetic field of practically the entire sun."

This revelation increases the work load for space weather forecasters, but it also increases the potential accuracy of their forecasts.(read more)

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16
Dec 10

Cassini Spots Potential Ice Volcano on Saturn Moon

Source: NASA/Cassini Mission

NASA's Cassini spacecraft has found possible ice volcanoes on Saturn's moon Titan that are similar in shape to those on Earth that spew molten rock.


Image of a Cassini flyover of an area of Saturn's moon Titan known as Sotra Facula.
Image credit: NASA/JPL-Caltech/USGS/University of Arizona

Topography and surface composition data have enabled scientists to make the best case yet in the outer solar system for an Earth-like volcano landform that erupts in ice. The results were presented today at the American Geophysical Union meeting in San Francisco.

"When we look at our new 3-D map of Sotra Facula on Titan, we are struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki in Iceland and even some small volcanic cones and flows near my hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping work, and is a Cassini radar team member and geophysicist at the U.S. Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also called cryovolcanoes, exist on ice-rich moons, and if they do, what their characteristics are. The working definition assumes some kind of subterranean geological activity warms the cold environment enough to melt part of the satellite's interior and sends slushy ice or other materials through an opening in the surface. Volcanoes on Jupiter's moon Io and Earth spew silicate lava.

Some cryovolcanoes bear little resemblance to terrestrial volcanoes, such as the tiger stripes at Saturn's moon Enceladus, where long fissures spray jets of water and icy particles that leave little trace on the surface. At other sites, eruption of denser materials might build up volcanic peaks or finger-like flows. But when such flows were spotted on Titan in the past, theories explained them as non-volcanic processes, such as rivers depositing sediment. At Sotra, however, cryovolcanism is the best explanation for two peaks more than 1,000 meters (3,000 feet) high with deep volcanic craters and finger-like flows.

"This is the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite," said Jeffrey Kargel, a planetary scientist at the University of Arizona, Tucson. "It's possible the mountains are tectonic in origin, but the interpretation of cryovolcano is a much simpler, more consistent explanation."

Kirk and colleagues analyzed new Cassini radar images. His USGS group created the topographic map and 3-D flyover images of Sotra Facula. Data from Cassini's visual and infrared mapping spectrometer revealed the lobed flows had a composition different from the surrounding surface. Scientists have no evidence of current activity at Sotra, but they plan to monitor the area.

"Cryovolcanoes help explain the geological forces sculpting some of these exotic places in our solar system," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "At Titan, for instance, they explain how methane can be continually replenished in the atmosphere when the sun is constantly breaking that molecule down."

Cassini launched Oct. 15, 1997, and began orbiting Saturn in 2004. Saturn has more than 60 known moons, with Titan being the largest. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency (ASI). JPL manages the mission for NASA's Science Mission Directorate at the agency's Headquarters in Washington.

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16
Dec 10

Hot Plasma Explosions Inflate Saturn's Magnetic Field

Source: NASA/JPL Press Release

A new analysis based on data from NASA's Cassini spacecraft finds a causal link between mysterious, periodic signals from Saturn's magnetic field and explosions of hot ionized gas, known as plasma, around the planet.


Artist's concept of the Saturnian plasma sheet.
Credit: NASA/JPL/JHUAPL

Scientists have found that enormous clouds of plasma periodically bloom around Saturn and move around the planet like an unbalanced load of laundry on spin cycle. The movement of this hot plasma produces a repeating signature "thump" in measurements of Saturn's rotating magnetic environment and helps to illustrate why scientists have had such a difficult time measuring the length of a day on Saturn.

"This is a breakthrough that may point us to the origin of the mysteriously changing periodicities that cloud the true rotation period of Saturn," said Pontus Brandt, the lead author on the paper and a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "The big question now is why these explosions occur periodically."

The data show how plasma injections, electrical currents and Saturn's magnetic field -- phenomena that are invisible to the human eye -- are partners in an intricate choreography. Periodic plasma explosions form islands of pressure that rotate around Saturn. The islands of pressure "inflate" the magnetic field.

A new animation showing the linked behavior is available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

The visualization shows how invisible hot plasma in Saturn's magnetosphere – the magnetic bubble around the planet -- explodes and distorts magnetic field lines in response to the pressure. Saturn's magnetosphere is not a perfect bubble because it is blown back by the force of the solar wind, which contains charged particles streaming off the sun.

The force of the solar wind stretches the magnetic field of the side of Saturn facing away from the sun into a so-called magnetotail. The collapse of the magnetotail appears to kick off a process that causes the hot plasma bursts, which in turn inflate the magnetic field in the inner magnetosphere.

Scientists are still investigating what causes Saturn's magnetotail to collapse, but there are strong indications that cold, dense plasma originally from Saturn's moon Enceladus rotates with Saturn. Centrifugal forces stretch the magnetic field until part of the tail snaps back.

The snapping back heats plasma around Saturn and the heated plasma becomes trapped in the magnetic field. It rotates around the planet in islands at the speed of about 100 kilometers per second (200,000 mph). In the same way that high and low pressure systems on Earth cause winds, the high pressures of space cause electrical currents. Currents cause magnetic field distortions.

A radio signal known as Saturn Kilometric Radiation, which scientists have used to estimate the length of a day on Saturn, is intimately linked to the behavior of Saturn's magnetic field. Because Saturn has no surface or fixed point to clock its rotation rate, scientists inferred the rotation rate from timing the peaks in this type of radio emission, which is assumed to surge with each rotation of a planet. This method has worked for Jupiter, but the Saturn signals have varied. Measurements from the early 1980s taken by NASA's Voyager spacecraft, data obtained in 2000 by the ESA/NASA Ulysses mission, and Cassini data from about 2003 to the present differ by a small, but significant degree. As a result, scientists are not sure how long a Saturn day is.

"What's important about this new work is that scientists are beginning to describe the global, causal relationships between some of the complex, invisible forces that shape the Saturn environment," said Marcia Burton, the Cassini fields and particles investigation scientist at NASA's Jet Propulsion Laboratory, Pasadena, California "The new results still don't give us the length of a Saturn day, but they do give us important clues to begin figuring it out. The Saturn day length, or Saturn's rotation rate, is important for determining fundamental properties of Saturn, like the structure of its interior and the speed of its winds."

Plasma is invisible to the human eye. But the ion and neutral camera on Cassini's magnetospheric imaging instrument provides a three-dimensional view by detecting energetic neutral atoms emitted from the plasma clouds around Saturn. Energetic neutral atoms form when cold, neutral gas collides with electrically-charged particles in a cloud of plasma. The resulting particles are neutrally charged, so they are able to escape magnetic fields and zoom off into space. The emission of these particles often occurs in the magnetic fields surrounding planets.

By stringing together images obtained every half hour, scientists produced movies of plasma as it drifted around the planet. Scientists used these images to reconstruct the 3-D pressure produced by the plasma clouds, and supplemented those results with plasma pressures derived from the Cassini plasma spectrometer. Once scientists understood the pressure and its evolution, they could calculate the associated magnetic field perturbations along the Cassini flight path. The calculated field perturbation matched the observed magnetic field "thumps" perfectly, confirming the source of the field oscillations.

"We all know that changing rotation periods have been observed at pulsars, millions of light years from our solar system, and now we find that a similar phenomenon is observed right here at Saturn," said Tom Krimigis, principal investigator of the magnetospheric imaging instrument, also based at the Applied Physics Laboratory and the Academy of Athens, Greece. "With instruments right at the spot where it's happening, we can tell that plasma flows and complex current systems can mask the real rotation period of the central body. That's how observations in our solar system help us understand what is seen in distant astrophysical objects."

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14
Dec 10

First four exoplanet system imaged directly

Source: KECK Observatory


An animation demonstrating plausible orbits of the HR 8799 planets through
one complete period (~465 years) of HR 8799b, the outermost planet.
Animation credit: LLNL & Q. M. Konopacky

Astronomers announced the discovery of a fourth giant planet joining three others orbiting a nearby star with information that challenges our current understanding of planet formation. The dusty young star named HR8799, located 129 light years away, was first recognized in 2008 when these same astronomers presented the first-ever images of a planetary system orbiting a star other than our sun.

Now, a research team from Lawrence Livermore National Laboratory (LLNL), National Research Council of Canada (NRC), the University of California Los Angeles, (UCLA) and Lowell Observatory has discovered a fourth planet that is about 7 times the mass of Jupiter – similar to the other three. Using high-contrast, near infrared adaptive optics on the Keck II telescope in Hawaii, the astronomers imaged the fourth planet (dubbed HR8799e) in 2009 and confirmed its existence and orbit in 2010. The research appears in the Dec. 8 edition of the journal, Nature.

“The images of this new inner planet in the system is the culmination of 10 years worth of innovations, making steady progress to optimize every observation and analysis step to allow the detection of planets located ever closer to their stars,” said Christian Marois, a former LLNL postdoc now at NRC, and first author of the new paper.

If this newly discovered planet was located in orbit around our sun, it would lie between Saturn and Uranus. This giant version of our solar system is young at about 30 million years old compared to our system, which is about 4.6 billion years old.

Scientific images of HR 8799.

Though the system is very much like our own, in other ways, it is much more extreme than our own – the combined mass of the four giant planets may be 20 times higher, and the asteroid and comet belts are dense and turbulent. In fact, the massive planets’ pull on each other gravitationally, and the system may be on the verge of falling apart.

This team of scientists simulated millions of years of evolution of the system, and showed that to have survived this long, the three inner planets may have to orbit like clockwork, with the new planet going around the star exactly four times while the second planet finishes two orbits in the time it takes the outer planet to complete one. This behavior was first seen in the moons of Jupiter but has never before been seen on this scale.

Studying the planet’s orbits also will help estimate their masses. “Our simulations show that if the objects were not planets, but supermassive ‘brown dwarfs’, the system would have fallen apart already,” said Quinn Konopacky, a postdoctoral researcher at LLNL’s Institute of Geophysics and Planetary Physics and a key author of the paper. “The implication is that we have truly found a unique new system of planets.” (Brown dwarfs are “failed stars”, too low in mass to sustain stable hydrogen fusion but larger than planets.) “We don’t yet know if the system will last for billions of years, or fall apart in a few million more. As astronomers carefully follow the HR 8799 planets during the coming decades, the question of just how stable their orbits are could become much clearer.”

The origin of these four giant planets remains a puzzle. It neither follows the “core accretion” model, in which planets form gradually close to stars where the dust and gas are thick or the “disk fragmentation” model in which a turbulent planet-forming disk rapidly cools and collapses out at its edges. Bruce Macintosh, a senior scientist at LLNL and the principal investigator for the Keck Observatory program, said: “There’s no simple model that can make all four planets at their current location. It’s a challenge for our theoretical colleagues.”

Previous observations had shown evidence for a dusty asteroid belt orbiting closer to the star – the new planet’s gravity helps account for the location of those asteroids, confining their orbits just like Jupiter does in our solar system. “Besides having four giant planets, both systems contain also two so-called “debris belts” composed of small rocky and/or icy objects along with lots of tiny dust particles, similar to the asteroid and Kuiper comet belts of our solar system”, noted co-author Ben Zuckerman, a professor of physics and astronomy at UCLA.

“Images like these bring the exoplanet field into the era of characterization. Astronomers can now directly examine the atmospheric properties of four giant planets orbiting another star that are all the same young age and that formed from the same building materials.” said Travis Barman, a Lowell Observatory exoplanet theorist and co-author of the current paper.

“I think there’s a very high probability that there are more planets in the system that we can’t detect yet,” Macintosh said. “One of the things that distinguishes this system from most of the extrasolar planets that are already known is that HR8799 has its giant planets in the outer parts - like our solar system does - and so has ‘room’ for smaller terrestrial planets – far beyond our current ability to see – in the inner parts.”

“It’s amazing how far we’ve come in a few years,” Macintosh said. “In 2007, when we first saw the system, we could barely see two planets out past the equivalent of Pluto’s orbit. Now we’re imaging a fourth planet almost where Saturn is on our solar system. It’s another step to the ultimate goal – still more than a decade away – of a picture showing another planet like Earth.”

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14
Dec 10

Voyager 1 sees solar wind decline on travel to interstellar space

Source:NASA

The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.

Artist's impression of Voyager 1. Image credit: NASA

Now hurtling toward interstellar space some 10.8 billion miles from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.

The event is a major milestone in Voyager 1's passage through the heliosheath, the turbulent outer shell of the sun's sphere of influence, and the spacecraft's upcoming departure from our solar system.

"The solar wind has turned the corner," said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. "Voyager 1 is getting close to interstellar space."

Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.

Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1's Low-Energy Charged Particle Instrument to deduce the solar wind's velocity.

When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft's speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 10.6 billion miles from the sun.

Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind's outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 45,000 mph each year since August 2007, when the solar wind was speeding outward at about 130,000 mph. The outward speed has remained at zero since June.

The results were presented at the American Geophysical Union meeting in San Francisco.

"When I realized that we were getting solid zeroes, I was amazed," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again."

Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere's structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate
Voyager 1 will cross that frontier in about four years.

"In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts," said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. "Once again, we face the predicament of redoing our models."

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12
Dec 10

The Geminids are coming

The night of December 13th and morning of the 14th will probably host the best meteor shower in the heavens this year. This meteor shower, the Geminids, is known for producing up to 60 multicolored meteors per hour at its peak.


Geminid meteor. Image credit: Wally Pacholka, TWAN

Some estimates say there could be as many as 120 meteors an hour can be visible from dark-sky locations. The radiant point for this shower, that gives the meteor shower its name, is  in the constellation Gemini. This year the Moon will set early in the evening setting the sky up for a spectacular show.

Best viewing will probably occur after midnight.

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11
Dec 10

ESA discovers that wind and water have shaped Schiaparelli on Mars

Source: ESA


Schiaparelli in perspective.
Image credits: ESA/DLR/FU Berlin (G. Neukum)

The small crater embedded in the northwestern rim of the Schiaparelli impact basin features prominently in this new image from ESA’s Mars Express. All around is evidence for past water and the great martian winds that periodically blow. (read more)

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11
Dec 10

WISE Sees an Explosion of Infrared Light

Source: NASA/JPL


Supernova remnant IC 443 as seen by WISE.
Image credit: NASA/JPL-Caltech/UCLA

A circular rainbow appears like a halo around an exploded star in this new view of the IC 443 nebula from NASA's Wide-field Infrared Survey Explorer, or WISE.

When massive stars die, they explode in tremendous blasts, called supernovae, which send out shock waves. The shock waves sweep up and heat surrounding gas and dust, creating supernova remnants like the one pictured here. The supernova in IC 443 happened somewhere between 5,000 and 10,000 years ago.

In this WISE image, infrared light has been color-coded to reveal what our eyes cannot see. The colors differ primarily because materials surrounding the supernova remnant vary in density. When the shock waves hit these materials, different gases were triggered to release a mix of infrared wavelengths.

The supernova remnant's northeastern shell, seen here as the violet-colored semi-circle at top left, is composed of sheet-like filaments that are emitting light from iron, neon, silicon and oxygen gas atoms and dust particles heated by a fast shock wave traveling at about 100 kilometers per second, or 223,700 mph.

The smaller southern shell, seen in bright bluish colors, is constructed of clumps and knots primarily emitting light from hydrogen gas and dust heated by a slower shock wave traveling at about 30 kilometers per second, or 67,100 miles per hour. In the case of the southern shell, the shock wave is interacting with a nearby dense cloud. This cloud can be seen in the image as the greenish dust cutting across IC 443 from the northwest to southeast.

IC 443 can be found near the star Eta Geminorum, which lies near Castor, one of the twins in the constellation Gemini.

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10
Dec 10

Akatsuki orbital insertion delayed for six years

Source: JAXA

Artist impression of the Akatsuki orbiting Venus.
Image credits: AFP/Akihiko Ikeshita.

The Japanese Space Agency, JAXA, has launched an investigation into a failed attempt to put a craft into orbit around Venus. Akatsuki, which blasted off in May, was due to study Venus's violent atmosphere and confirm if there are active volcanoes on its surface. However, yesterday the craft failed to reduce its speed sufficiently to fall into the gravitational pull of the planet. Astronomers will now have to wait over six years for the mission to return to Venus before attempting to put it into orbit again.

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10
Dec 10

Cosmic dark ages brought to light

Source: Physicsworld.com

A humble piece of kit located in the Australian outback has revealed how the universe emerged from a period called the cosmic dark ages nearly 13 billion years ago. This was the time when the first stars and galaxies began to assert their influence on cosmic evolution, by bombarding the intergalactic medium with ultraviolet light until it had become a warm, ionized plasma. (read more)

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8
Dec 10

Japan's first Venus probe struggling to enter orbit

Source: AFP


Artist impression of the Akatsuki orbiting Venus.
Image credits: AFP/Akihiko Ikeshita.

Japan’s first Venus space probe encountered problems while attempting orbit insertion and went into safe mode. It took  about an hour and a half to regain communications with the probe after a 22 minute blackout with the Akatsuki spacecraft, and controllers seem to still be trying to ascertain the spacecraft’s orbit.

The Planet-C Venus Climate Orbiter, a box-shaped golden satellite fitted with two paddle-shaped solar panels, blasted off from a space centre in southern Japan in May. The probe, nicknamed "Akatsuki" or "Dawn", reversed its engine to slow down and enter the planet's gravitational field but lost contact with ground control longer than had been anticipated, the Japan Aerospace Exploration Agency (JAXA) said.

It was presumed to have shifted itself into a "safe hold mode", and was able to communicate only by via one of its three antennae after the blackout ended.

From translated Twitter reports and a document posted on the JAXA website, it appears engineers confirmed ignition of the thruster before Akatsuki moved behind Venus, but had trouble pinpointing the spacecraft after the blackout should have ended. They have regained some radio communications.

“It is not known which path the probe is following at the moment,” a JAXA official Munetaka Ueno told reporters at the ground control late Tuesday, according to AFP. “We are making maximum effort to readjust the probe.” (read more)

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