Geochemist: Helium and Lead isotopes provide insight into Earth's core

This map of the Samoan hotspot shows its division into three parallel volcanic lineaments. 

Credit: UCSB

A UC Santa Barbara geochemist studying Samoan volcanoes has found evidence of the planet's early formation still trapped inside the Earth.

Known as hotspots, volcanic island chains such as Samoa can ancient primordial signatures from the early solar system that have somehow survived billions of years.

Matthew Jackson, an associate professor in UCSB's Department of Earth Science, and colleagues utilized high-precision lead and helium isotope measurements to unravel the chemical composition and geometry of the deep mantle plume feeding Samoa's volcanoes.

Their findings appear today in the journal Nature.

In most cases, volcanoes are located at the point where two tectonic plates meet, and are created when those plates collide or diverge.

Hotspot volcanoes, however, are not located at plate boundaries but rather represent the anomalous melting in the interior of the plates.

Such intraplate volcanoes form above a plume-fed hotspot where the Earth's mantle is melting.

The plate moves over time, at approximately the rate human fingernails grow (3 inches a year), and eventually the volcano moves off the hotspot and becomes extinct.

Another volcano forms in its place over the hotspot and the process repeats itself until a string of volcanoes evolves.

"So you end up with this linear trend of age-progressive volcanoes," Jackson said. "On the Pacific plate, the youngest is in the east and as you go to the west, the volcanoes are older and more deeply eroded."

"Hawaii has two linear trends of volcanoes, most underwater, which are parallel to each other. There's a southern trend and a northern trend."

Because the volcanic composition of parallel Hawaiian trends is fundamentally different, Jackson and his team decided to look for evidence of this in other hotspots.

In Samoa, they found three volcanic trends exhibiting three different chemical configurations as well as a fourth group of a late-stage eruption on top of the third trend of volcanoes. These different groups exhibit distinct compositions.

"Our goal was to figure out how we could use this distribution of volcano compositions at the surface to reverse-engineer how these components are distributed inside this upwelling mantle plume at depth," Jackson said.

Each of the four distinct geochemical compositions, or endmembers, that the scientists identified in Samoan lavas contained low Helium-3 (He-3) and Helium-4 (He-4) ratios.

The surprising discovery was that they all exhibited evidence for mixing with a fifth, rare primordial component consisting of high levels of He-3 and He-4.

"We have really strong evidence that the bulk of the plume is made of the high Helium-3, -4 component," Jackson said.

"That tells us that most of this plume is primordial material and there are other materials hosted inside of this plume with low Helium-3, -4, and these are likely crustal materials sent into the mantle at ancient subduction zones."

The unique isotopic topology revealed by the researchers' analysis showed that the four low-helium endmembers do not mix efficiently with one another. However, each of them mixes with the high He-3 and He-4 component.

"This unique set of mixing relationships requires a specific geometry for the four geochemical flavors within the upwelling plume: They must be hosted within a matrix that is composed of the rare fifth component with high He-3," Jackson explained.

"This new constraint on plume structure has important implications for how deep mantle material is entrained in plumes, and it gives us the clearest picture yet for the chemical structure of an upwelling mantle plume."

More Information
Helium and lead isotopes reveal the geochemical geometry of the Samoan plume - M. G. Jackson, S. R. Hart, J. G. Konter, M. D. Kurz, J. Blusztajn & K. A. Farley Corresponding Author: Nature 514, 355–358 (16 October 2014) doi:10.1038/nature13794

Evidence of forming planet discovered 335 light years from Earth

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

Credit: P. Marenfeld & NOAO/AURA/NSF

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Early Earth: A Battered, Hellish World with Water Oases for Life

Asteroids and comets that repeatedly smashed into the early Earth covered the planet's surface with molten rock during its earliest days, but still may have left oases of water that could have supported the evolution of life, scientists say.

The new study reveals that during the planet's infancy, the surface of the Earth was a hellish environment, but perhaps not as hellish as often thought, scientists added.

Earth formed about 4.5 billion years ago. The first 500 million years of its life are known as the Hadean Eon.

Although this time amounts to more than 10 percent of Earth's history, little is known about it, since few rocks are known that are older than 3.8 billion years old.

An artistic conception of the early Earth-moon system showing the Earth's surface after being bombarded with large impacts, causing magma extrusion on the surface, though some liquid water was retained. Image released on July 30, 2014. 

Credit: Simone Marchi

Earth's violent youth
For much of the Hadean, Earth and its sister worlds in the inner solar system were pummeled with an extraordinary number of cosmic impacts.

"It was thought that because of these asteroids and comets flying around colliding with Earth, conditions on early Earth may have been hellish," said lead study author Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colorado.

Simone Marchi

This imagined hellishness gave the eon its name, Hadean comes from the word Hades, the lord of the underworld in Greek mythology.

However, in the past dozen years or so, a radically different picture of the Hadean began to emerge.

Analysis of minerals trapped within microscopic zircon crystals dating from this eon "suggested there was liquid water on the surface of the Earth back then, clashing with the previous picture that the Hadean was hellish," Marchi said.

This could explain why the evidence of the earliest life on Earth appears during the Hadean, maybe the planet was less inhospitable during that eon than previously thought.

This artist's illustration shows a close-up of the early Earth, revealing magma extrusion on the surface and the scars from severe cosmic bombardment. Image released on July 30, 2014.

Credit: Simone Marchi

Cosmic bombardment history
The exact timing and magnitude of the impacts that smashed Earth during the Hadean are unknown.

To get an idea of the effects of this bombardment, Marchi and his colleagues looked at the moon, whose heavily cratered surface helped model the battering that its close neighbour Earth must have experienced back then.

"We also looked at highly siderophile elements (elements that bind tightly to iron), such as gold, delivered to Earth as a result of these early collisions, and the amounts of these elements tells us the total mass accreted by Earth as the result of these collisions," Marchi said.

Prior research suggests these impacts probably contributed less than 0.5 percent of the Earth's present-day mass.

The researchers discovered that "the surface of the Earth during the Hadean was heavily affected by very large collisions, by impactors larger than 100 kilometers (60 miles) or so, really, really big impactors," Marchi said.

"When Earth has a collision with an object that big, that melts a large volume of the Earth's crust and mantle, covering a large fraction of the surface," Marchi added.

These findings suggest that Earth's surface was buried over and over again by large volumes of molten rock, enough to cover the surface of the Earth several times. This helps explain why so few rocks survive from the Hadean, the researchers said.

However, although these findings might suggest that the Hadean was a hellish eon, the researchers found that "there were time gaps between these large collisions," Marchi said.

"Generally speaking, there may have been something on the order of 20 or 30 impactors larger than 200 km (120 miles) across during the 500 million years of the Hadean, so the time between such impactors was relatively long," Marchi said.

Any water vapourised near these impacts "would rain down again," Marchi said, and "there may have been quiet tranquil times between collisions, there could have been liquid water on the surface."

The researchers suggested that life emerging during the Hadean was probably resistant to the high temperatures of the time.

Marchi and his colleagues detailed their findings in the July 31 issue of the journal Nature.

More Information: Widespread mixing and burial of Earth’s Hadean crust by asteroid impacts. - Authors: S. Marchi, W. F. Bottke, L. T. Elkins-Tanton, M. Bierhaus, K. Wuennemann, A. Morbidelli & D. A. Kring - doi:10.1038/nature13539

SETI Kelper: Planet bonanza hints at worlds similar to our own

The artist concept depicts multiple-transiting planet systems, which are stars with more than one planet. 

The planets eclipse or transit their host star from the vantage point of the obplanetserver. This angle is called edge-on. 

Credit: NASA

For hunters, this has been a bountiful year. A team lead of astronomers at the SETI Institute and NASA Ames Research Center have used data from NASA's Kepler space telescope to uncover 715 new exoplanets.

The newly-verified objects orbit 305 different stars, and therefore include multi-world systems that are reminiscent of the Sun's own planetary family.

The announcement of these discoveries was followed by news that Kepler had also found the first Earth-size planet in the habitable zone of its star, Kepler 186f.

This is a significant milestone in the task of determining the prevalence of terrestrial planets in the Milky Way galaxy.

Jason Rowe

"These results are showing us that not only are Earth-sized planets common, but so are multi-planet systems containing potentially habitable worlds," notes Jason Rowe, a SETI Institute astronomer who co-led the study.

"Most of the new planets orbit their host star much closer than Mercury, but a few are beginning to bear a similarity to our own solar system."

The deluge of new planets has been intensified by a new analysis scheme called verification by multiplicity.

This technique can be applied to many planets at once, allowing the researchers to verify hundreds of new planetary systems in wholesale fashion, rather than teasing them from the Kepler data one-by-one as done in the past.

The new technique uses probability arguments based on the recognition that, of the 150,000 stars observed by Kepler, hundreds were found that have multiple planet candidates.

David Black

On this basis, the researchers are assured that their results are not distorted by binary stars that can mimic a multi-world system.

The new discoveries increase the total number of known exoplanets to over 1,700.

"From this work we've also learned that planets in these multiple systems are small, and their orbits are flat and circular, much like our own solar system," Rowe said.

On April 17th, the Kepler team announced the discovery of Kepler 186f, the first Earth-sized planet found in the habitable zone of its host star, marking a major milestone in determining the frequency of Earth-like planets in the Milky Way galaxy.

"Uncovering these worlds and showing that habitable worlds could be very common has increased the likelihood that there is life, perhaps abundant life, elsewhere in the cosmos," notes David Black, President and CEO of the SETI Institute.

Data collection from the Kepler mission ended in the spring of last year, due to the failure of a second on-board reaction wheel, essential to accurate pointing of the telescope.

However, on May 20th, NASA announced the approval of the K2 mission, intended to repurpose Kepler to use the pressure of sunlight hitting the side of the spacecraft to act as a third wheel.

"We can't continue to look at the original Kepler star field," said Douglas Caldwell, Kepler Instrument Scientist at the SETI Institute, "but spacecraft are built and operated by very smart people, and thanks to the hard work of the entire Kepler team we can now search for planets in a wide variety of environments and conditions, including star forming regions. Doing so will teach us more about how our own planetary system formed and evolved."

"The more we explore the more we find worlds among the stars that remind us of home," Rowe notes.

More information: Jason Rowe is presenting these results at this week's annual meeting of the Canadian Astronomical Society (CASCA) in Quebec: casca2014.craq-astro.ca/index_en.php

ESA Venus Express VITRIS: Ready to aerobrake through planet's atmosphere

This global view of the southern hemisphere of Venus is a mosaic of images obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board ESA’s Venus Express on 16 May 2006. 

The night-side hemisphere (in red at the top) is made of infrared images taken at 1.74 micrometres, showing the lower layers of the cloud deck surrounding the planet at about 45-km altitude. 

The day-side hemisphere (in blue at the bottom) is made of ultraviolet images taken at 480 nanometres. 

It shows the cloud top layer at about 65-km altitude. 

The red part of the central panel was taken at 3.8 micrometres, and shows the double vortex at the south pole, at an altitude of about 60 km, surrounded by a collar of ‘cold’ air. 

Credit: ESA /VIRTIS-VenusX IASF-INAF, Observatoire de Paris (R.Hueso, Univ. Bilbao)

Newly discovered celestial object defies categories

This is an image of the ROXs 42B system obtained with the Keck telescope. 

The star is located in the center of the masked region. 

ROXs 42Bb orbits at about 150 astronomical units (AU). 

(1 AU=the distance from Earth to the Sun.) 

The other object ("c") is a likely unrelated background star. 

Credit: Thayne Currie

An object discovered by astrophysicists at the University of Toronto (U of T) nearly 500 light years away from the Sun may challenge traditional understandings about how planets and stars form.

The object is located near and likely orbiting a very young star about 440 light years away from the Sun, and is leading astrophysicists to believe that there is not an easy-to-define line between what is and is not a planet.

Thayne Currie

"We have very detailed measurements of this object spanning seven years, even a spectrum revealing its gravity, temperature, and molecular composition. Still, we can't yet determine whether it is a planet or a failed star – what we call a 'brown dwarf'. Depending on what measurement you consider, the answer could be either," said Thayne Currie, a post-doctoral fellow in U of T's Department of Astronomy & Astrophysics and lead author of a report on the discovery published this week in Astrophysical Journal Letters.

Named ROXs 42Bb for it's proximity to the star ROXs 42B, the object is approximately nine times the mass of Jupiter, below the limit most astronomers use to separate planets from brown dwarfs, which are more massive.

However, it is located 30 times further away from the star than Jupiter is from the Sun.

"This situation is a little bit different than deciding if Pluto is a planet. For Pluto, it is whether an object of such low mass amongst a group of similar objects is a planet," said Currie.

"Here, it is whether an object so massive yet so far from its host star is a planet. If so, how did it form?"

Most astronomers believe that gas giant planets like Jupiter and Saturn formed by core accretion, whereby the planets form from a solid core that then accretes a massive gaseous envelope.

Core accretion operates most efficiently closer to the parent star due to the length of time required to first form the core.

An alternate theory proposed for forming gas giant planets is disk instability – a process by which a fragment of a disk gas surrounding a young star directly collapses under its own gravity into a planet. This mechanism works best farther away from the parent star.

More information: The discovery is reported in a study titled "Direct imaging and spectroscopy of a candidate companion below/near the deuterium-burning limit in the young binary star system, ROXs 42B" which can also be viewed on arXiv.org at arxiv.org/abs/1310.4825.

Currie will present these and other findings at the annual meeting of the American Astronomical Society in Washington, DC this week.

KOI-314c: Newfound planet is Earth-mass but gassy

KOI-314c, shown in this artist's conception, is the lightest planet to have both its mass and physical size measured. 

Surprisingly, although the planet weighs the same as Earth, it is 60 percent larger in diameter, meaning that it must have a very thick, gaseous atmosphere. 

It orbits a dim, red dwarf star (shown at left) about 200 light-years from Earth. 

KOI-314c interacts gravitationally with another planet, KOI-314b (shown in the background), causing transit timing variations that allow astronomers to measure the masses of both worlds. 

This serendipitous discovery resulted from analysis as part of the Hunt for Exomoons with Kepler (HEK) project. 

Credit: C. Pulliam & D. Aguilar (CfA)

An international team of astronomers has discovered the first Earth-mass planet that transits, or crosses in front of, its host star.

KOI-314c is the lightest planet to have both its mass and physical size measured. Surprisingly, although the planet weighs the same as Earth, it is 60 percent larger in diameter, meaning that it must have a very thick, gaseous atmosphere.

"This planet might have the same mass as Earth, but it is certainly not Earth-like," says David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery.

"It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants."

Kipping presented this discovery today in a press conference at the 223rd meeting of the American Astronomical Society.

The team gleaned the planet's characteristics using data from NASA's Kepler spacecraft. KOI-314c orbits a dim, red dwarf star located approximately 200 light-years away.

It circles its star every 23 days. The team estimates its temperature to be 220 degrees Fahrenheit, too hot for life as we know it.

KOI-314c is only 30 percent denser than water. This suggests that the planet is enveloped by a significant atmosphere of hydrogen and helium hundreds of miles thick.

It might have begun life as a mini-Neptune and lost some of its atmospheric gases over time, boiled off by the intense radiation of its star.

Weighing such a small planet was a challenge. Conventionally, astronomers measure the mass of an exoplanet by measuring the tiny wobbles of the parent star induced by the planet's gravity.

This radial velocity method is extremely difficult for a planet with Earth's mass. The previous record holder for a planet with a measured mass (Kepler-78b) weighed 70 percent more than Earth.

To weigh KOI-314c, the team relied on a different technique known as transit timing variations (TTV). This method can only be used when more than one planet orbits a star.

The two planets tug on each other, slightly changing the times that they transit their star.

David Nesvorny

"Rather than looking for a wobbling star, we essentially look for a wobbling planet," explains second author David Nesvorny of the Southwest Research Institute (SwRI).

"Kepler saw two planets transiting in front of the same star over and over again. By measuring the times at which these transits occurred very carefully, we were able to discover that the two planets are locked in an intricate dance of tiny wobbles giving away their masses."

The second planet in the system, KOI-314b, is about the same size as KOI-314c but significantly denser, weighing about 4 times as much as Earth.

It orbits the star every 13 days, meaning it is in a 5-to-3 resonance with the outer planet.

TTV is a very young method of finding and studying exoplanets, first used successfully in 2010. This new measurement shows the potential power of TTV, particularly when it comes to low-mass planets difficult to study using traditional techniques.

"We are bringing transit timing variations to maturity," adds Kipping.

The planet was discovered by chance by the team as they scoured the Kepler data not for exoplanets, but for exomoons.

The Hunt for Exomoons with Kepler (HEK) project, led by Kipping, scans through Kepler's planet haul looking for TTV, which can also be a signature of an exomoon.

"When we noticed this planet showed transit timing variations, the signature was clearly due to the other planet in the system and not a moon. At first we were disappointed it wasn't a moon but then we soon realized it was an extraordinary measurement," says Kipping.

Does a planet need life to create continents?

Earth may not have possessed the continents it does now if not for life, instead becoming a planet covered nearly entirely in ocean.

If not for life, Earth may not have possessed the continents it does now, instead becoming a planet covered nearly entirely in ocean, researchers say.

These new findings suggest that any continents astronomers may one day see on alien worlds may potentially be signs of extraterrestrial life, scientists added.

Earth is currently the only known planet in the universe that has liquid water on its surface.

There is life virtually wherever there is liquid water on Earth, so one main focus of the search for extraterrestrial life as we know it is the region around a star where it is neither too hot nor too cold for liquid water to exist on a planet, an area known as the star's habitable zone.

Although water covers most of Earth's surface, nearly 30 percent of the planet is covered by land, sustaining a dazzling variety of life.

Scientists might one day be capable of telling if distant planets are similarly covered by land, oceans and clouds by looking for reddish, bluish or grayish tints in the colour of those worlds.

Researchers have already developed maps of clouds on a giant planet orbiting a distant star.

Now researchers suggest Earth would have been a water world with very few continents, if any at all, without the presence of life.

A great deal of research has shown that life has had a major impact on the evolution of Earth's atmosphere and oceans.

Plants and other photosynthetic life generate oxygen, giving Earth the only known atmosphere in the universe with significant levels of oxygen.

Life also greatly influences how much carbon is in the atmosphere and oceans in the form of carbon dioxide and methane.

These greenhouse gases trap heat and can dramatically affect Earth's climate, which in turn has an effect on how much of Earth's water is frozen as ice.

Oxygen can also indirectly cool Earth's climate by removing methane from the atmosphere—in fact, the dramatic rise of oxygen in Earth's atmosphere about 2.4 billion years ago, known as the Great Oxidation Event, may have cooled the planet enough to for it become a frozen "Snowball Earth."

"However, much less is known about whether life has had any effects on the deeper interior of Earth," said study author Tilman Spohn, a planetary scientist at DLR, the German Aerospace Center's Institute of Planetary Research in Berlin.

Past research noted the oldest signs of life found so far are roughly 3.5 billion years old, about the same time continents began growing, and suggested a potential link between these events.

The scientists then explored whether or not the evolution of life on Earth could have influenced the evolution of the planet.

The investigators focused on biological weathering, by which life breaks down rock.

This crumbled rock gets blown and washed away by wind and water, sediment that eventually makes its way to subduction zones, the areas where one tectonic plate of the Earth's crust dives or subducts under another.

NASA's Cassini Spacecraft: Saturn's rings cast shadows on the planet

The spectacular rings of Saturn cast dark shadows on the ringed planet as the winter season approaches in Saturn's southern hemisphere in this view from the Cassini spacecraft. 

With the cold season comes a blue hue on Saturn that is likely caused by a drop in ultraviolet sunlight and haze it produces. This image was taken on July 29, 2013 and released on Dec. 23.

Credit: NASA /JPL-Caltech /Space Science Institute

NASA's Cassini spacecraft has capped 2013 with a spectacular new collection of Saturn photos showcasing the planet's beauty, as well with its trademark rings and strange moons.

The newly released Saturn photos by Cassini include two views of Enceladus, Saturn's sixth-largest moon. Enceladus is a winter-appropriate ice world.

Geysers at its poles shoot ice particles into space, some of which make it into orbit around Saturn. Some of this space "snow" becomes part of Saturn's E ring, Saturn's second outermost ring that is made of microscopic particles.

Other images highlight Saturn's largest moon, Titan. There are no jolly elves at Titan's north pole; liquid methane and ethane seas appear as splotchy features near the moon's poles.

At the south pole, a high-altitude vortex swirls. The hazy orange atmosphere of Titan is thought to resemble the atmosphere of early Earth.

NASA Messenger: Sunlight on the Side of the Planet Mercury

Another day, another beautiful view of Mercury's horizon. 

In this scene, which was acquired looking from the shadows toward the sunlit side of the planet, a 120-km (75 mi.) impact crater stands out near the center.

Emanating from this unnamed crater are striking chains of secondary craters, which gouged linear tracks radially away from the crater.

While this crater is not especially fresh (its rays have faded into the background), it does appear to have more prominent secondary crater chains than many of its peers.

This image was acquired on Oct. 2, 2013 by the Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) aboard NASA's MESSENGER spacecraft, as part of the MDIS's limb imaging campaign.

Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb.

These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere.

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the solar system's innermost planet.

During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Strange solitary planet without companion star in Milky Way

Artist's conception of PSO J318.5-22. Credit: MPIA/V. Ch. Quetz

An international team of astronomers has discovered an exotic young planet that is not orbiting a star.

This free-floating planet, dubbed PSO J318.5-22, is just 80 light-years away from Earth and has a mass only six times that of Jupiter.

The planet formed a mere 12 million years ago—a newborn in planet lifetimes.

It was identified from its faint and unique heat signature by the Pan-STARRS 1 (PS1) wide-field survey telescope on Haleakala, Maui.

Follow-up observations using other telescopes in Hawaii show that it has properties similar to those of gas-giant planets found orbiting around young stars. And yet PSO J318.5-22 is all by itself, without a host star.

"We have never before seen an object free-floating in space that that looks like this.

Michael Liu

It has all the characteristics of young planets found around other stars, but it is drifting out there all alone," explained team leader Dr. Michael Liu of the Institute for Astronomy at the University of Hawaii at Manoa.

"I had often wondered if such solitary objects exist, and now we know they do."

During the past decade, extrasolar planets have been discovered at an incredible pace, with about a thousand found by indirect methods such as wobbling or dimming of their host stars induced by the planet.

However, only a handful of planets have been directly imaged, all of which are around young stars (less than 200 million years old).

PSO J318.5-22 is one of the lowest-mass free-floating objects known, perhaps the very lowest. But its most unique aspect is its similar mass, color, and energy output to directly imaged planets.

"Planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars. PSO J318.5-22 is not orbiting a star so it will be much easier for us to study.

It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth," said Dr. Niall Deacon of the Max Planck Institute for Astronomy in Germany and a co-author of the study.

More information: The discovery paper of PSO J318.5-22 is being published by Astrophysical Journal Letters and is available at arxiv.org/abs/1310.0457

Nasa Cassini Image: Saturn's rings form a majestic arc over the planet

Saturn's rings appear to form a majestic arc over the planet in this image from NASA's Cassini spacecraft.

This view looks toward the sunlit side of the rings from about 17 degrees above the ringplane. 

The image was taken with the Cassini spacecraft wide-angle camera on June 15, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 705 nanometers.

The view was acquired at a distance of approximately 657,000 miles (1.1 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 2 degrees. Image scale is 37 miles (60 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. 

The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology (CalTech) in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C.

The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Image Credit: NASA/JPL-Caltech/Space Science Institute

Ozone hole might slightly warm planet

A map of ozone concentrations in the Southern Hemisphere shows thinning of the ozone layer over the South Pole. 

This region of reduced ozone, which is called the "ozone hole," causes changes in wind patterns and cloud cover. 

Credit: NASA

A lot of people mix up the ozone hole and global warming, believing the hole is a major cause of the world's increasing average temperature. Scientists, on the other hand, have long attributed a small cooling effect to the ozone shortage in the hole.

Now a new computer-modeling study suggests that the ozone hole might actually have a slight warming influence, but because of its effect on winds, not temperatures.

The new research suggests that shifting wind patterns caused by the ozone hole push clouds farther toward the South Pole, reducing the amount of radiation the clouds reflect and possibly causing a bit of warming rather than cooling.

Kevin Grise

"We were surprised this effect happened just by shifting the jet stream and the clouds," said lead author Kevin Grise, a climate scientist at Lamont-Doherty Earth Observatory of Columbia University in New York City.

Grise notes this small warming effect may be important for climatologists trying to predict the future of Southern Hemisphere climate.

The work is detailed in Geophysical Research Letters, a journal of the American Geophysical Union.

Each ozone molecule consists of three oxygen atoms bound together. These ozone molecules gather in the lower portion of the stratosphere about 20 to 30 kilometers (12 to 19 miles) above the ground—about twice as high as commercial airliners fly.

Thankfully for the living things below, this layer of ozone shields Earth from some of the hazardous ultraviolet radiation barraging the atmosphere. Unchecked, these ultraviolet rays can cause sunburns, eye damage and even skin cancer.

In the 1980s, scientists discovered thinning of the ozone layer above Antarctica during the Southern Hemisphere's spring months.

The cause of this "hole" turned out to be chlorofluorocarbons, such as Freon, from cooling systems, aerosols cans and degreasing solvents, which break apart ozone molecules.

Even though the1987 Montreal Protocol banned these chlorofluorocarbons worldwide, the ozone hole persists decades later.

More information: The Ozone Hole Indirect Effect: Cloud-Radiative Anomalies Accompanying the Poleward Shift of the Eddy-Driven Jet in the Southern Hemisphere, in Geophysical Research Letters. onlinelibrary.wiley.com/doi/10.1002/grl.50675/abstract

NASA Messenger: Mercury's Volcanic Past Made Planet Look Younger

Even the oldest areas of Mercury's surface (outlined in white) are still younger than the planet itself. Image released on July 3, 2013.

CREDIT: John Hopkins APL

Mercury is looking good for its age.

Even the oldest parts of the surface of the planet closest to the sun are only 4 billion to 4.1 billion years old, not 4.5 billion years old — the age at which the planet formed, a new study finds.

"If the oldest surface visible on Mercury is 4 billion or 4.1 billion years old, then that would imply that the first perhaps 500 million or 400 million years of the planet have been erased," said Simone Marchi, a Southwest Research Institute planetary scientist and lead author of the study.

 "They are gone. There is no record of the oldest surface of Mercury, and we expect that Mercury pretty much formed like the Earth or the moon around 4.5 billion years ago."

Marchi's research suggests that widespread volcanic activity on Mercury during its early years as a planet is to blame for the artificially young surface.

One reason for this could be that when the solar system was pelted with asteroids early in its history, Mercury's thin crust was punctured by space rocks, Marchi said.

The impacts may have caused increased volcanism on the planet, effectively resurfacing the entire planet a short time after Mercury formed.

The team used a detailed map of Mercury by NASA's Messenger spacecraft in orbit around the planet to characterize the oldest regions on the planet's surface.

"Unfortunately we do not have samples from Mercury so we cannot really have precise age estimates of the terrains, but therefore the only thing we can possibly do is just look at the craters," Marchi told reporters.

"If there are more craters, this implies that the surface is older."

Older bits of the planet's face have had the most time to be impacted by errant space rocks, therefore making them the most cratered parts of a planetary body, Marchi said.

Scientists used this to their advantage. By characterizing the most pockmarked parts of the planet, Marchi and his team could compare the number of craters on any given part of Mercury to the number of craters on certain parts of the moon — a celestial object whose surface age is well documented.

"One of the major outcomes of the Apollo program was that those data allow us to make a connection between the number of craters that were observed on some lunar terrain and the true age of those terrains," Marchi said.

"In that way, we calibrated the model and we know how many craters you have as a function of age of the terrain."

"That information we extrapolated out to Mercury using current astronomical models that predict what the impact flux from asteroids is on the moon and what the impact rate [is] on Mercury, so this model will tell us how we have to scale or extrapolate this lunar crater chronology to Mercury," Marchi added.

The model shows that for every one crater formed on a given surface on the moon per year, a similar surface on Mercury is dotted with three new craters in the same amount of time, Marchi said.

NASA's $446 million Messenger probe (which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was launched in 2004 and has been in orbit around Mercury since 2011.

The new research is detailed in this week's issue of the journal Nature.

Geoscientists predict new compounds change our view of what planets are made of

Structures of the newly predicted magnesium oxides: On the left, MgO2; on the right, Mg3O2. Green – Mg atoms, red – O atoms. Isosurfaces show regions of high electron localization.

A team of researchers led by Artem R. Oganov, a professor of theoretical crystallography in the Department of Geosciences, Stony Brook University, has made a startling prediction that challenges existing chemical models and current understanding of planetary interiors—magnesium oxide, a major material in the formation of planets, can exist in several different compositions.

Artem R. Oganov

The team's findings, "Novel stable compounds in the Mg-O system under high pressure," are published in the online edition of Physical Chemistry Chemical Physics.

The existence of these compounds—which are radically different from traditionally known or expected materials—could have important implications.

"For decades it was believed that MgO is the only thermo-dynamically stable magnesium oxide, and it was widely believed to be one of the main materials of the interiors of the Earth and other planets," said Qiang Zhu, the lead author of this paper and a postdoctoral student in the Oganov laboratory.

"We have predicted that two new compounds, MgO2 and Mg3O2, become stable at pressures above one and five million atmospheres, respectively. This not only overturns standard chemical intuition but also implies that planets may be made of totally unexpected materials. We have predicted conditions (pressure, temperature, oxygen fugacity) necessary for stability of these new materials, and some planets, though probably not the Earth, may offer such conditions," added Oganov.

In addition to their general chemical interest, MgO2 and Mg3O2 might be important planet-forming minerals in deep interiors of some planets. Planets with these compounds would most likely be the size of Earth or larger.

Qiang Zhu

The team explained how its paper predicted the structures in detail by analysing the electronic structure and chemical bonding for these compounds. For example, Mg3O2 is forbidden within "textbook chemistry," where the Mg ions can only have charges "+2," O ions are "-2, and the only allowed compound is MgO.

In the "oxygen-deficient" semiconductor Mg3O2, there are strong electronic concentrations in the "empty space" of the structure that play the role of negatively charged ions and stabilize this material.

Curiously, magnesium becomes a d-element (i.e. a transition metal) under pressure, and this almost alchemical transformation is responsible for the existence of the "forbidden" compound Mg3O2.

The findings were made using unique methods of structure prediction, developed in the Oganov laboratory.

"These methods have led to the discovery of many new phenomena and are used by a number of companies for systematically discovering novel materials on the computer—a much cheaper route, compared to traditional experimental methods," said Zhu.

"It is known that MgO makes up about 10 percent of the volume of our planet, and on other planets this fraction can be larger. The road is now open for a systematic discovery of new unexpected planet-forming materials," concluded Oganov.

More information: 
Zhu Q., Oganov A.R., Lyakhov A.O. (2013). Novel stable compounds in the Mg-O system under high pressure. Phys. Chem. Chem. Phys., in press. pubs.rsc.org/en/content/articlelanding/2013/cp/c3cp50678a

NASA Messenger Spacecraft: Completes Map of Planet Mercury

Scientists use images from NASA's Messenger spacecraft to create these global views of Mercury, the most complete maps ever. The images were released on Feb. 22, 2013.

CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The surface of the planet Mercury has been completely mapped for the first time in history, scientists say.

The closest planet to the sun hasn't received as much scientific attention as some of its more flashy solar system neighbours, such as Mars, but NASA's Messenger spacecraft is helping to close the gap.

Papers published in Science Express provide support for the long-held hypothesis that Mercury's permanently shadowed polar craters contain water ice. 

The probe has been in orbit around Mercury since March 2011, and its team announced Feb. 28 that the spacecraft had finished mapping the planet's surface.

"We can now say we have imaged every square meter of Mercury's surface from orbit," said Messenger principal investigator Sean Solomon of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Admittedly, some regions are in permanent shadow, but we're actually peering into those shadows with our imaging systems."



Before Messenger, less than half the surface had been imaged by NASA's Mariner 10 spacecraft, which made several flybys of Mercury in 1974 and 1975.

Messenger is the first probe to orbit the planet. In addition to photographing the unseen parts of Mercury, the spacecraft substantially improved on the resolution of existing maps.

"When we set out with the Messenger mission we didn't know if the planet would look like the other half that was seen in the '70s," Solomon reported.

"There was a great debate over how important volcanism was in the history of Mercury."

Messenger quickly showed that not only did volcanism occur during Mercury's past, but it might have been widespread.

The spacecraft also revealed never-before-seen types of terrain on the planet, such as surface pockmarks called hollows that scientists suspect are created when volatile materials sublimate off the surface.

"Unstable material is exposed to the temperatures and space environment, and slowly over thousands, maybe millions, of years, it's lost to Mercury's atmosphere and to space, to create a depression or hollow in an area where there are often many such hollows that etch the terrain," Solomon said.

Subaru Optics Image: Spiral structure of disk may reveal planets

An image of the disk around SAO 206462 captured with Subaru's  HiCIAO. A coronagraph blocks the direct light of the central star, which appears as the black, circular area in the image. Arrows show the two arms of the spiral structure around the star. Credit: NAOJ 

An international team of astronomers has used HiCIAO (High Contrast Instrument for the Subaru Next Generation Optics) to observe a disk around the young star SAO 206462.

They succeeded in capturing clear, detailed images of its disk, which they discovered has a spiral structure with two discernable arms.

On the basis of their observations and modeling according to spiral density wave theory, the team suspects that dynamic processes, possibly resulting from planets in the disk, may be responsible for its spiral shape.

This research may provide the basis for another indirect method of detecting planets. Scientists have known that planets form in a broad disk of dust and gas surrounding a star, a so-called "protoplanetary disk."

However, the composition of these special disks as well as the process by which they give rise to planets have remained a mystery.

The bright light of a central star makes it difficult to detect fainter objects around it or to capture a detailed image of the composition of the disk itself.

Recent research with HiCIAO, Subaru Telecope's "planet-hunter", has overcome some of those obstacles.

By masking the bright light from the central star, the instrument can then detect more detailed features of the star's disk and the objects that it contains. 

Earth Type planet in Alpha Centauri system

An Earth-mass planet has been found orbiting a star in the Alpha Centauri system, the Sun's next door neighbour in space.

This is an artist's impression of a planet orbiting the star Alpha Centauri B.

Picture: AFP/Getty Images

Scientists Discover Planet with Diamond Mantle - Twice The Size Of Our Sun

Scientists have announced the discovery of a planet made almost entirely of diamonds.

The planet, called 55 Cancri e, is located in a solar system inside the constellation of Cancer, reports NBC News.

It was discovered in 2004, and scientists have been working since then to determine its mass and radius, as well as study its host star’s composition.

The planet is called a “super-Earth,” and scientists believe that the rocky world is composed mostly of carbon (in the form of either graphite or diamond). It also includes iron, silicon carbide, and possibly silicates.

Scientists also believe, based on their research, that at least one-third of the planet’s mass is pure diamond. Lead researcher Nikku Madhusudhan of Yale University stated:

“This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth. The surface of this planet is likely covered in graphite and diamond rather than water and granite.”

While worlds like the “diamond planet” of 55 Cancri e have been theorized before, and at least one has been discovered before now, it is the first of its kind to be identified orbiting around a sun-like star.

Madhusudhan’s study on the planet was published in the journal Astrophysical Journal Letters.

Princeton University astronomer David Spergel stated that it is relatively easy to find out a star’s basic structure and history once its age and mass have been discovered. He added:

“Planets are much more complex. This ‘diamond-rich super-Earth’ is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars.”

NASA Claims Giant Vesta Not an Asteroid But a Small Planet

Nasa scientists have discovered that the giant Vesta is a small planet, not an asteroid. They claim that Vesta will give them more clues to the creation of terrestrial planets and the earth's moon.

Using Nasa's Dawn spacecraft, scientists have found that Vesta contains important planetary building blocks as well as some essential minerals.

Scientists have also found a unique pattern of minerals on Vesta that shows that the asteroid was once a planet. These minerals were exposed by deep gashes created by space rock impact which may support the idea that the asteroid once had a subsurface magma ocean. A magma ocean occurs when a body undergoes almost complete melting, leading to layered building blocks that can form planets. Other bodies with magma oceans ended up becoming parts of earth and other planets.

"Dawn's visit to Vesta has confirmed our broad theories of this giant asteroid's history, while helping to fill in details it would have been impossible to know from afar," said Carol Raymond, deputy principal investigator at Nasa's Jet Propulsion Laboratory in Pasadena. "Dawn's residence at Vesta of nearly a year has made the asteroid's planet-like qualities obvious and shown us our connection to that bright orb in our night sky."

According to the scientists, Vesta's Rheasilvia basin in the southern hemisphere is much higher and wider, relative to its crater size, than the central peaks of craters on bodies like our moon. Vesta bears some similarities to other low-gravity worlds like Saturn's small icy moons, and its surface has light and dark markings that do not match the predictable patterns on earth's moon.

"We know a lot about the moon and we're only coming up to speed now on Vesta," said Vishnu Reddy, researcher at the Max Planck Institute for Solar System Research in Germany and the University of North Dakota in Grand Forks. "Comparing the two gives us two storylines for how these fraternal twins evolved in the early solar system."

The scientists have now found those two giant impacts that pounded Vesta's southern hemisphere and created the basin Veneneia approximately two billion years ago and the Rheasilvia basin about one billion years ago. Rheasilvia is the largest impact basin on Vesta.

"The large impact basins on the moon are all quite old," said David O'Brien, a Dawn participating scientist from the Planetary Science Institute in Tucson, Ariz. "The fact that the largest impact on Vesta is so young was surprising."

Another shocking discovery was that some meteorites found on earth actually originate from Vesta. They found some minerals such as iron and magnesium on those meteorites; these minerals match those of rocks on Vesta's surface.