New Telescope Monitors Our Home Star

A new solar telescope, scheduled to launch this winter, will probe the sun's atmosphere and inner workings, helping scientists better understand how solar storms.


During its five-year mission, the Earth-orbiting Solar Dynamics Observatory (SDO) will seek to reveal how the sun's magnetic field works, what governs the ups and downs of the solar cycle and how solar activity affects Earth.


"The sun is a magnetic variable star that fluctuates on times scales ranging from a fraction of a second to billions of years," said Madhulika Guhathakurta, lead program scientist for the Living With a Star program (of which SDO is a part) at NASA Headquarters in Washington, D.C. "SDO will show us how variable the sun really is and reveal the underlying physics of solar variability."


Tracing magnetic fields


SDO will measure and observe the sun's magnetic field, which powers all solar activity. Flow of hot, ionized gases in the sun's convection zone — the region inside the sun where hot gas parcels rise and transport energy to the surface — act as electrical currents to generate the sun's magnetic field.


The observatory will look at the fields at the surface of the sun and use those measurements to infer exactly where the fields originate inside the sun and where they are expressed as active regions, such as sunspots and coronal loops, to where they eject particles into space as coronal mass ejections and solar flares (both of which can impact the function of satellites and electrical grids on Earth).


The goal is to better understand how the sun's magnetic field is generated and how its energy impacts solar radiation, which in turn affects the rest of the solar system, including Earth.


Ups and downs


SDO will also follow changes in the sun's activity, which is known to rise and fall on a roughly 11-year cycle. A solar cycle is at its maximum when the greatest number of sunspots is counted in a year; the minimum occurs when the fewest are seen. Both of these markers can only be recognized after they have been passed.


And of course, the solar cycle doesn't always follow that 11-year course. Between 1645 and 1715, for example, sunspots were rarely observed — a period called the Maunder Minimum — and Europe and North America both experienced bitterly cold winters — a time known as the "Little Ice Age." (The sun is currently in a lull, with next maximum expected in 2013.)


The potential connection between low levels of solar activity and Earth's climate are something scientists want to better understand in the hopes that they could eventually learn to predict these ups and downs.


Tools for the job


To make all of these observations, SDO will use three science instruments:


The Helioseismic and Magnetic Imager (HMI) will peer into the sun and map the surface of the sun's magnetic fields, as well as the plasma flows that generate magnetic fields.



The Atmospheric Imaging Assembly (AIA) will image the solar atmosphere in multiple wavelengths that cannot be seen from the ground. HMI and AIA will together link changes on the solar surface to the sun's interior.


The Extreme Ultraviolet Variability Experiment (EVE) will measure how much energy the sun emits at extreme ultraviolet wavelengths, which can only be observed from space because they are completely blocked out by Earth's atmosphere. These wavelengths of light are important to study because they can affect astronauts out in space.


SDO will watch the sun almost 24 hours a day as it orbits the Earth in a figure-eight path. The spacecraft will take images of the sun every few seconds with the visual quality of an IMAX movie, giving scientists an unprecedented look at our parent star.

Ancient Mars Lakes Revealed in New Images

Vast lakes of melted ice existed on Mars more recently than previously thought during a warm, wet spell on the red planet, new images suggest.

The lakes might have been habitats for life, if there ever was life on Mars. So far, however, there is no firm evidence of any Martian biology, past or present.

The photographs, taken by NASA's Mars Reconnaissance Orbiter, reveal a network of winding channels linking together several depressions in the Martian surface. Researchers say those channels could only have been caused by Martian lake water running between the depressions about 3 billion years ago – which is 1 billion years more recent than earlier estimates.

"Most of the research on Mars has focused on its early history and the recent past," said researcher Nicholas Warner, who led the study at the Imperial College of London. "Excitingly, our study now shows that this middle period in Mars' history was much more dynamic than we previously thought."

The new images suggest lakes as large as 12 miles (20 km) wide once dotted the equatorial regions of Mars, researchers said.

Scientists already know that water ice exists today beneath the Martian surface based on data from landers, rovers and Mars images taken from orbit. But past studies have hinted that Mars was warm and wet enough to support liquid lakes around 4 billion years ago.

Using the images captured by the Mars Reconnaissance Orbiter, Warner and his colleagues concluded that Mars could have sustained lakes even later, in a period known as the Hesperian Epoch.

"Scientists had largely overlooked the Hesperian Epoch as it was thought that Mars was then a frozen wasteland," Warner said.

But Warner and his team found that during that epoch 3 billion years ago, Mars could have been warmed by volcanic activity, meteorite impacts or even orbital shifts. The result would be a temporary increase in planetary temperature as the gases created in those events thickened the Martian atmosphere.

The research is detailed in the Jan. 4 issue of the science journal Geology. Scientists at the University College London also participated in the study.

The channels revealed by the Mars Reconnaissance Orbiter are the key, researchers said. They run between huge depressions in the Martian surface located near a 1,242-mile (2,000 km) gorge called Ares Vallis across the planet's equator.

Scientists previously thought the depressions were formed by a process called sublimation, when ice transitions directly into gas. That process would create gaps as ice sublimates from the Martian surface, leading to a collapse that would form the depression.

But sublimation alone would not explain the channels, researchers said. Similar channels can be seen on Earth in Alaska and Siberia, where permafrost melts to carve drainage channels that connect different lakes, they added.

Warner and his team are unsure how long the more recent warm, wet period on Mars may have lasted, or how long liquid water could have flowed between the lakes. But the ancient lakebeds from the current study could provide attractive targets for future probes to seek out regions on Mars that may have once been habitable for microbial life, they added.

The scientists plan to seek other potential lakebeds in other regions along Mars' equator using more images from the Mars Reconnaissance Orbiter. Launched in 2005, the orbiter is NASA's most powerful spacecraft circling Mars today and has collected more images of the Martian surface than all other missions to the red planet combined.

Glowing Nebula Reveals Cosmic Cat's Paw. (Star Forming Region in Central Milky Way. 5000ly)

Large pic


A stunning new image of the Cat's Paw Nebula reveals a region at the heart of our Milky Way galaxy where new stars are being born at a furious pace.

The nebula, a cloud of interstellar gas and dust, is a cosmic nursery where new stars are ushered into being as these materials mix and condense.

Also known as NGC 6334, the Cat's Paw is thought to hold several tens of thousands of stars. Among them are freshly minted, brilliant blue stars — each nearly 10 times the mass of our sun and born within the last few million years.

"NGC 6334 is one of the most active nurseries of massive stars in our galaxy," researchers said in a European Southern Observatory statement.

The new photos were taken with the Wide Field Imager instrument at the 2.2-metre MPG/ESO telescope at the La Silla Observatory in Chile. The view achieves its stunning pinks and purples by combining images taken through blue, green and red filters, as well as a special filter designed to let through the light of glowing hydrogen.

The nebula appears red because its blue and green light are scattered and absorbed more efficiently by material between the nebula and Earth. The red light comes predominantly from hydrogen gas glowing under the intense glare of hot young stars.

The roiling, red bubble in the lower right part of the image may be a star expelling a large amount of matter at high speed as it nears the end of its life, scientists said in a statement. Another possibility is that the star has already died, and we are seeing the remnants left behind after it exploded, they added.

The Cat's Paw Nebula is about 5,500 light-years away from Earth, in the direction of the constellation Scorpius (the Scorpion). It extends about 50 light-years across, and covers an area on the sky slightly larger than the full moon.

Crater on the Moon Gets Stunning Close-Up - Good For Crater Mechanics Study

Rays of material ejected during the impact are still visible around Tycho, as is the central heap of debris that resulted when melted material flowed back down the crater's slopes and solidified in the middle. Because it is so well preserved, Tycho offers a unique chance to study the mechanics of how craters form, researchers said in a statement

As The Crust Turns: Cassini Data Show Enceladus in Motion

January 11, 2010


Blobs of warm ice that periodically rise to the surface and churn the icy crust on Saturn's moon Enceladus explain the quirky heat behavior and intriguing surface of the moon's south polar region, according to a new paper using data from NASA's Cassini spacecraft.

"Cassini appears to have caught Enceladus in the middle of a burp," said Francis Nimmo, a planetary scientist at the University of California Santa Cruz and a co-author of the new paper in Nature Geoscience. "These tumultuous periods are rare and Cassini happens to have been watching the moon during one of these special epochs."

The south polar region captivates scientists because it hosts the fissures known as "tiger stripes" that spray water vapor and other particles out from the moon. While the latest paper, released on Jan. 10, doesn't link the churning and resurfacing directly to the formation of fissures and jets, it does fill in some of the blanks in the region's history.

"This episodic model helps to solve one of the most perplexing mysteries of Enceladus," said Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., of the research done by his colleagues. "Why is the south polar surface so young? How could this amount of heat be pumped out at the moon's south pole? This idea assembles the pieces of the puzzle."

About four years ago, Cassini's composite infrared spectrometer instrument detected a heat flow in the south polar region of at least 6 gigawatts, the equivalent of at least a dozen electric power plants. This is at least three times as much heat as an average region of Earth of similar area would produce, despite Enceladus' small size. The region was also later found by Cassini's ion and neutral mass spectrometer instrument to be swiftly expelling argon, which comes from rocks decaying radioactively and has a well-known rate of decay.

Calculations told scientists it would be impossible for Enceladus to have continually produced heat and gas at this rate. Tidal movement – the pull and push from Saturn as Enceladus moves around the planet – cannot explain the release of so much energy.

The surface ages of different regions of Enceladus also show great diversity. Heavily cratered plains in the northern part of the moon appear to be as old as 4.2 billion years, while a region near the equator known as Sarandib Planitia is between 170 million and 3.7 billion years old. The south polar area, however, appears to be less than 100 million years old, possibly as young as 500,000 years.

Craig O'Neill of Macquarie University in Sydney, Australia, and Nimmo, who was partially funded by the NASA Outer Planets Research program, adapted a model that O'Neill had developed for the convection of Earth's crust. For Enceladus, which has a surface completely covered in cold ice that is fractured by the tug of Saturn's gravitational pull, the scientists stiffened up the crust. They picked a strength somewhere between that of the malleable tectonic plates on Earth and the rigid plates of Venus, which are so strong, it appears they never get sucked down into the interior.

Their model showed that heat building up from the interior of Enceladus could be released in episodic bubbles of warm, light ice rising to the surface, akin to the rising blobs of heated wax in a lava lamp. The rise of the warm bubbles would send cold, heavier ice down into the interior. (Warm is, of course, relative. Nimmo said the bubbles are probably just below freezing, which is 273 degrees Kelvin or 32 degrees Farenheit, whereas the surface is a frigid 80 degrees Kelvin or -316 degrees Farenheit.)

The model fits the activity on Enceladus when the churning and resurfacing periods are assumed to last about 10 million years, and the quiet periods, when the surface ice is undisturbed, last about 100 million to two billion years. Their model suggests the active periods have occurred only 1 to 10 percent of the time that Enceladus has existed and have recycled 10 to 40 percent of the surface. The active area around Enceladus's south pole is about 10 percent of its surface.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

Spots Like the Sun's Revealed on Giant Star

A snapshot taken of a giant star hundreds of light-years from Earth has revealed two enormous bright spots - the first direct evidence of sun-like heat transportation on another star, scientists say.

The new infrared view shows the behemoth star Betelgeuse with two bright blotches near its center. The bright spots are hotter than the surrounding area, indicating regions of convection where heat rises from the interior of the star to its surface, just like on the sun.

The convection may play a role in Betelgeuse's known and prolific weight loss, researchers said. The star is shedding the equivalent of one sun's worth of mass every 10,000 to 100,000 years. It is also expelling a gigantic plume of hot gas that may be related to the convection, researchers said.

Betelgeuse is a red supergiant star 600 light-years away and easy to spot in the night sky. It forms the right shoulder of the "hunter" in the constellation Orion. The star is enormous, about 600 times the size of the sun and 20 times as massive.

"The situation on Betelgeuse seems pretty much different than in the case of the sun," said astronomer Guy Perrin, a co-leader of the research team at the Paris Observatory. "The convective cells are far much larger."

The bright spots, like the star itself, are also vast, with the larger of the two spanning of more than 139 million miles – 1 1/2 times the distance between the Earth and our sun, researchers said. This larger spot is about one-quarter the star's diameter, they added. Similar spots on the sun are about one-twentieth the width of the star.

An international team of astronomers led by Paris Observatory astronomer Xavier Haubois and Perrin observed the Betelgeuse bright spots using three telescopes in Arizona and a method called interferometry – which combines observations from different telescopes into a cohesive whole to provide greater sensitivity. The spots, researchers said, indicate that in supergiants there is active convection, which is the process of heat moving through matter currents.

"The star has a patchy surface produced by a few convective cells," Perrin told SPACE.com in an e-mail. "Now we need to better understand the physical properties of these cells to go further: their temperature, their lifetime, their connection to magnetic fields, etcetera."

Convection is the process that brings bubbles to the surface of boiling water in your kitchen.

On the sun, bright convection hotspots and darker lulls (cooler areas) can easily be observed from Earth and are well-known. But that's not the case with supergiant stars like Betelgeuse, where the size, longevity and dynamics of convection structures remain a mystery.

The surface of Betelgeuse is typically about 3,600 Kelvin (6,020 degrees Fahrenheit), with the bright spots burning about 500 degrees Kelvin (440 degrees F) hotter, researchers said. The surface of the sun, for comparison, is about 5,810 degrees Kelvin (10,000 degrees F).

Researchers plan to study other layers of Betelgeuse to better understand the interaction between its surface, atmosphere and interior, as well as how they compare to other supergiant stars.

"Betelgeuse may not be an isolated case and is not necessarily peculiar with respect to other stars of the same class," Perrin said. "So we may anticipate similar cells on other red supergiants."

The research, announced Tuesday, is detailed in an October 2009 edition of the journal Astronomy & Astrophysics

Light from Faraway Planet Directly Detected

For the first time, astronomers have directly detected the light signature of a planet orbiting an almost sun-like star. This signature can tell scientists the chemical makeup of the planet, which can help them understand how it formed. in the future these signatures could be used to look for signs of life on other planets.

The planet is a giant, about 10 times as massive as Jupiter, and it orbits between two other giants around a star similar to our sun in a scaled-up version of our own solar system.

The three giant companions were detected in 2008 and range in mass from seven to 10 times that of Jupiter, with orbits between 20 and 70 times as far from their host star as Earth is from the sun. The system also features two belts of smaller objects, similar to the asteroid and Kuiper belts around our sun. The system's star is about 1.5 times as massive as the sun.

Previously, scientists have taken the spectra of stars – or the signature of the amount of light they reflect and radiate at different wavelengths – by watching an "exoplanetary eclipse" with a space telescope. As the exoplanet passes directly behind its host star from the perspective of Earth, the light that comes only from the planet can be subtracted out from that that comes from the star.

But, this method can only be used on the small fraction of exoplanets that have the right kind of orientation with respect to the Earth.

The team of astronomers that observed the giant planet were able to do so without looking for an eclipse, instead detecting the planet's light directly with a ground-based telescope: the European Southern Observatory's Very Large Telescope in Chile.

"After more than five hours of exposure time, we were able to tease out the planet's spectrum from the host star's much brighter light," said team member Carolina Bergfors.

Picking out the planet's light is tricky because the host star is several thousand times brighter than the planet.

"It's like trying to see what a candle is made of, by observing it from a distance of two kilometers [1.2 miles] when it's next to a blindingly bright 300 Watt lamp," said team member Markus Janson of the University of Toronto.

The light spectrum of the planet can show what the atmosphere of the world is like, though in this case it reveals that the atmosphere is still poorly understood, not matching up to any current models.

Eventually, though, scientists hope to be able to more easily detect chemical signs of life on other worlds by their signatures in light spectra. Certain molecules that are important to life or a potential sign of it that have been found are carbon dioxide, water vapor, silicate minerals and sodium.

The team hopes to use the same methods to get the spectra of the other two giant planets in the system, to do a comparison between them.

"This will surely shed new light on the processes that lead to the formation of planetary system like our own," Janson said.

The team's findings are detailed in the Astrophysical Journal.

Exoplanets Clue to Sun's Curious Chemistry

A ground-breaking census of 500 stars, 70 of which are known to host planets, has successfully linked the long-standing “lithium mystery” observed in the Sun to the presence of planetary systems. Using ESO’s successful HARPS spectrograph, a team of astronomers has found that Sun-like stars that host planets have destroyed their lithium much more efficiently than “planet-free” stars. This finding does not only shed light on the lack of lithium in our star, but also provides astronomers with a very efficient way of finding stars with planetary systems.
“For almost 10 years we have tried to find out what distinguishes stars with planetary systems from their barren cousins,” says Garik Israelian, lead author of a paper appearing this week in the journal Nature. “We have now found that the amount of lithium in Sun-like stars depends on whether or not they have planets.”

Low levels of this chemical element have been noticed for decades in the Sun, as compared to other solar-like stars, and astronomers have been unable to explain the anomaly. The discovery of a trend among planet-bearing stars provides a natural explanation to this long-standing mystery. “The explanation of this 60 year-long puzzle is for us rather simple,” adds Israelian. “The Sun lacks lithium because it has planets.”

This conclusion is based on the analysis of 500 stars, including 70 planet-hosting stars. Most of these stars were monitored for several years with ESO’s High Accuracy Radial Velocity Planet Searcher. This spectrograph, better known as HARPS, is attached to ESO's 3.6-metre telescope and is the world’s foremost exoplanet hunter. “This is the best possible sample available to date to understand what makes planet-bearing stars unique,” says co-author Michel Mayor.

The astronomers looked in particular at Sun-like stars, almost a quarter of the whole sample. They found that the majority of stars hosting planets possess less than 1% of the amount of lithium shown by most of the other stars. “Like our Sun, these stars have been very efficient at destroying the lithium they inherited at birth,” says team member Nuno Santos. “Using our unique, large sample, we can also prove that the reason for this lithium reduction is not related to any other property of the star, such as its age.”

Unlike most other elements lighter than iron, the light nuclei of lithium, beryllium and boron are not produced in significant amounts in stars. Instead, it is thought that lithium, composed of just three protons and four neutrons, was mainly produced just after the Big Bang, 13.7 billion years ago. Most stars will thus have the same amount of lithium, unless this element has been destroyed inside the star.

This result also provides the astronomers with a new, cost-effective way to search for planetary systems: by checking the amount of lithium present in a star astronomers can decide which stars are worthy of further significant observing efforts.

Now that a link between the presence of planets and curiously low levels of lithium has been established, the physical mechanism behind it has to be investigated. “There are several ways in which a planet can disturb the internal motions of matter in its host star, thereby rearrange the distribution of the various chemical elements and possibly cause the destruction of lithium. It is now up to the theoreticians to figure out which one is the most likely to happen,” concludes Mayor.

Research paper (http://www.eso.org/public/outreach/press-rel/pr-2009/Lithium_israelian.pdf)
More info: Exoplanet Media Kit (http://www.eso.org/public/outreach/products/publ/brochures/pdf/exoplanet_lowres.pdf)

The infrared portrait of the Small Magellanic Cloud, taken by NASA's Spitzer Space Telescope, reveals the stars and dust in this galaxy as never seen before. The Small Magellanic Cloud is a nearby satellite galaxy to our Milky Way galaxy, approximately 200,000 light-years away.

The image shows the main body of the Small Magellanic Cloud, which is comprised of the "bar" on the left and a "wing" extending to the right. The bar contains both old stars (in blue) and young stars lighting up their natal dust (green/red). The wing mainly contains young stars. In addition, the image contains a galactic globular cluster in the lower left (blue cluster of stars) and emission from dust in our own galaxy (green in the upper right and lower right corners).

The data in this image are being used by astronomers to study the lifecycle of dust in the entire galaxy: from the formation in stellar atmospheres, to the reservoir containing the present day interstellar medium, and the dust consumed in forming new stars. The dust being formed in old, evolved stars (blue stars with a red tinge) is measured using mid-infrared wavelengths. The present day interstellar dust is weighed by measuring the intensity and color of emission at longer infrared wavelengths. The rate at which the raw material is being consumed is determined by studying ionized gas regions and the younger stars (yellow/red extended regions). The Small Magellanic Cloud, and its companion galaxy the Large Magellanic Cloud, are the two galaxies where this type of study is possible, and the research could not be done without Spitzer.

This image was captured by Spitzer's infrared array camera and multiband imaging photometer (blue is 3.6-micron light; green is 8.0 microns; and red is combination of 24-, 70- and 160-micron light). The blue color mainly traces old stars. The green color traces emission from organic dust grains (mainly polycyclic aromatic hydrocarbons). The red traces emission from larger, cooler dust grains.

The image was taken as part of the Spitzer Legacy program known as SAGE-SMC: Surveying the Agents of Galaxy Evolution in the Tidally-Stripped, Low Metallicity Small Magellanic Cloud.

NASA's Wise Eye Spies First Glimpse of the Starry Sky

January 06, 2010


PASADENA, Calif. -- NASA's Wide-field Infrared Survey Explorer, or WISE, has captured its first look at the starry sky that it will soon begin surveying in infrared light.

Launched on Dec. 14, WISE will scan the entire sky for millions of hidden objects, including asteroids, "failed" stars and powerful galaxies. WISE data will serve as navigation charts for other missions, such as NASA's Hubble and Spitzer Space Telescopes, pointing them to the most interesting targets the mission finds.

A new WISE infrared image was taken shortly after the space telescope's cover was removed, exposing the instrument's detectors to starlight for the first time. The picture shows about 3,000 stars in the Carina constellation and can be viewed online at http://www.nasa.gov/mission_pages/WISE/multimedia/wise20100106.html .

The image covers a patch of sky about three times larger than the full moon, and was presented today at the 215th meeting of the American Astronomical Society in Washington. The patch was selected because it does not contain any unusually bright objects, which could damage instrument detectors if observed for too long. The picture was taken while the spacecraft was staring at a fixed patch of sky and is being used to calibrate the spacecraft's pointing system.

When the WISE survey begins, the spacecraft will scan the sky continuously as it circles the globe, while an internal scan mirror counteracts its motion. This allows WISE to take "freeze-frame" snapshots every 11 seconds, resulting in millions of images of the entire sky.

"Right now, we are busy matching the rate of the scan mirror to the rate of the spacecraft, so we will capture sharp pictures as our telescope sweeps across the sky," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

To sense the infrared glow of stars and galaxies, the WISE spacecraft cannot give off any detectable infrared light of its own. This is accomplished by chilling the telescope and detectors to ultra-cold temperatures. The coldest of WISE's detectors will operate at less than 8 Kelvin, or minus 445 degrees Fahrenheit.

The first sky survey will be complete in six months, followed by a second scan of one-half of the sky lasting three months. The mission ends when the frozen hydrogen that keeps the instrument cold evaporates away, an event expected to occur in October 2010.

Preliminary survey images are expected to be released six months later, in April 2011, with the final atlas and catalog coming 11 months later, in March 2012. Selected images will be released to the public beginning in February 2010.

Super Earths May Be Superior at Fostering Life

Astronomers have discovered hundreds of Jupiter-like planets in our galaxy. However, a handful of the planets found orbiting distant stars are more Earth-sized. This gives hope to astrobiologists, who think we are more likely to find life on rocky planets with liquid water.

The rocky planets found so far are actually more massive than our own. Dimitar Sasselov, professor of astronomy at Harvard University, coined the term "Super-Earths" to reflect their mass rather than any superior qualities.

But Sasselov says that these planets – which range from about 2 to 10 Earth masses – could be superior to the Earth when it comes to sustaining life.

On Shaky Ground

It is said that 99 percent of all species that ever lived have gone extinct. Earth, it seems, is a tough place to call home. Our planet has gone through Ice Ages and global warming trends, it has been hit by comets and asteroids (leading, in one case, to a mass extinction that felled the mighty dinosaurs), and the amount of oxygen in the atmosphere has risen and fallen over time. Our planet is always in a state of flux, and life must adapt to these changes or die.

The shifting of tectonic plates is another example of Earth's restless nature. Continents bang together, forming mountains, only to be later torn apart. Islands grow from underwater volcanoes, and elements are liberated from rocks when they are melted beneath the crust.

While all this geologic activity makes us literally stand on shaky ground, scientists have come to believe that tectonics is one of the key features of our planet which makes life possible. If not for tectonics, carbon needed by life would stay locked within rocks.

The fear today is that too much carbon dioxide in the atmosphere will lead to global warming. Yet too little carbon dioxide in the atmosphere would make Earth a much colder place, and the photosynthetic plants and algae that rely on CO2 would perish. The demise of these oxygen-producing organisms would leave us all gasping for breath.

According to Sasselov, Earth's mass helps keeps tectonics in action. The more massive a planet, the hotter its interior. Tectonic plates slide on a layer of molten rock beneath the crust called the mantle. Convective currents within the mantle push the plates around. For smaller planets like Mars, the interior is not hot enough to drive tectonics.

Super Earths, with a larger and hotter interior, would have a thinner planetary crust placed under more stress. This probably would result in faster tectonics, as well as more earthquakes, volcanism, and other geologic upheavals. In fact, Sasselov says the plate tectonics on Super Earths may be so rapid that mountains and ocean trenches wouldn't have much time to develop before the surface was again recycled.

Venus, only slightly less massive than Earth, has had a great deal of volcanic activity, but it does not appear to have tectonics. This may be because low mass planets need water to lubricate the process, and Venus lost its water long ago through evaporation. Sasselov says Earth has just enough water for tectonics to work. Tectonics on Super Earths might be so efficient that water isn't even needed.

On the other hand, it's possible that a SuperEarth could be entirely covered by water. Sasselov says that in the case of such an ocean world, most of the water will be in an exotic state known as iceVII -- a very compressed, hard ice with a melting point above 212 degrees Fahrenheit (100 degrees Celsius).


Whether made of rock or ice, Sasselov says Super Earths will be only 1 or 2 times the actual size of Earth because they become densely compressed as they gain mass. This higher density will result in greater gravity. Sasselov says the most massive Super Earth would have about 3 times the gravity of Earth. Tests of human resistance to vertical G-force, where the blood is pulled down to the legs, have found the typical person can tolerate up to 5 Gs before losing consciousness. So while you might feel much heavier walking on a Super Earth, the extra gravity wouldn't be beyond what human explorers could endure. Of course, any life that evolved on a Super Earth would be adapted to the greater gravity, just as a human feels comfortable on the 1 G surface of Earth.

Habitable Hot Spots

This greater gravity means a Super Earth can easily hold onto an atmosphere, so it would not end up with a tenuous atmosphere like Mars. But the role of a planet's atmosphere in creating prime conditions for life can be tricky. Venus has a surface temperature of nearly 900 F (480 C) due to the thick greenhouse atmosphere that doesn't let heat escape.

One of the biggest influences on a planet's climate is the star it orbits. Earth has a circular orbit 150 million kilometers away from the Sun, a yellow dwarf star. This helps keep conditions warm enough so that our oceans don't freeze over, but cool enough so that we don't lose all our water through evaporation.

The Super Earths discovered so far orbit a variety of stars. The first Earth-like extrasolar planets ever found orbit a pulsar, a rotating neutron star that emits high energy radiation. The other Super Earths orbit stars that are smaller and cooler than our Sun.

Most of the known Super Earths are very close to their stars, closer than the planet Mercury is to the Sun. Even though these stars don't burn as brightly as our Sun, the planets are so close they are like burnt cinders flickering close to a fire.

One such hot Super Earth is CoRoT 7-b (named for the CoRoT telescope that was used to locate the planet). CoRoT 7-b orbits the orange dwarf star TYC 4799-1733-1 once every 20 hours. This planet is nearly 5 times the mass of Earth, but is less than twice as big. This solar system has another hot Super Earth, CoRoT-7c, which is 8 times as massive as Earth and circles the star in 3 days and 17 hours.

For astrobiologists hoping to find alien life, two Super Earths orbiting the star Gliese 581 have potential. Gliese 581, a mce_style="color: black;"> style='color:black'>red dwarf star, is cooler than our Sun. Based on their orbit around this star, planets Gliese 581-c and Gliese 581-d are thought to have habitable conditions, although some think planet "c" might have a runaway greenhouse atmosphere like Venus.

Another aspect affecting the potential for life is the presence of a companion moon. Earth's Moon helps balance our planet's rotation on its axis. Sasselov notes that a Super Earth's extra mass would give it a very stable rotation, so a moon would not be needed to help keep the planet in line.


Superior Alien Civilizations

Missions like the Kepler space telescope, launched just this year, could help astronomers find many Earth-like planets in the years to come. Sasselov estimates there could be a hundred million habitable Super Earth planets just in our Milky Way galaxy. He predicts we'll find 50 to 100 Super Earth planets in the next 5 years.


The existence of so many Super Earths could explain the "Fermi Paradox" of why aliens have not contacted us. If our lower mass planet does not have the ideal conditions for life, alien explorers would be less likely to look to us, choosing instead to target the many Super Earths in the galaxy.

"Earth is a marginal planet when it comes to conditions we would like to see for complex life to sustain itself," Sasselov notes. "In the family of Earth-like planets, the sweet spot for complex chemistry and biochemistry to emerge and sustain itself lies in planets larger than the Earth."

If aliens on Super Earths ever decided to investigate Earth to see if such a tiny world could harbor life, they would have a harder time sending rockets into space because of the higher gravity on their planet. "This could be another answer to the Fermi Paradox," says Sasselov, "but it's not an insurmountable problem." It could even be that because of their deeper gravity well, aliens living on Super Earths would have to develop a technology superior to our chemical rockets in order to explore the universe.

Sasselov's own suggestion for the Fermi paradox relates to the age and evolution of planets in the universe. When the universe was young, only hydrogen and helium were available. Generations of stellar evolution were needed to produce the heavier elements, such as silica and iron, which build rocky planets. Even though the universe is approximately 14 billion years old, our solar system only formed about 4.6 billion years ago. (Astronomers did find a 12.7-billion-year-old Jupiter-mass object in our galaxy, but Sasselov thinks this so-called ancient planet could instead be the remnant of a red or brown dwarf star that was stripped of some of its mass.)

If other rocky worlds with life are about as young as we are, then perhaps the lack of visiting spaceships indicates there are no ancient, highly advanced alien civilizations out there.

"Most life emerges on Super-Earths with habitable potential, but Super-Earths started forming in the galaxy only relatively recently, and few technical civilizations have managed to emerge since," Sasselov says.

Hubble Photographs Billowing Clouds of Cosmic Dust

http://i.space.com/images/091201-iris-nebula-02.jpg

A recent image taken by the Hubble Space Telescope reveals the perfect dust laboratory in the sky and could help astronomers pin down the raw ingredients needed to give birth to baby stars.


The stellar photo is a composite of four images taken with different filters by Hubble's Advanced Camera for Surveys. The resulting close-up shot reveals the northwest region of the Iris Nebula, or NGC 7023. The nebula is a region of star formation that lies about 1,400 light-years away in the constellation of Cepheus. (A light-year is the distance light will travel in a year, which is about 6 trillion miles, or 10 trillion km).


The image shows billowing mounds of cosmic dust. Such dust is made up of tiny particles of solid matter ranging in size from 10 to 100 times smaller than the dust grains you might find blanketing household furniture on terra firma.


The scientists were particularly interested in parts of the nebula that appeared redder than expected. Considered a reflection nebula, NGC 7023 scatters light from a massive nearby star, which in this case is a star called HD 200775 that's 10 times the mass of the sun. Typically, reflection nebulae appear blue, because dust grains scatter blue light more efficiently than red.


(The other variety of nebula, called emission nebulae, are hot enough to emit light themselves and tend to appear red.)


Some hydrocarbon-based compound must be causing these dusty filaments to take on the red tinge, the researchers figure.


In addition to studying the detailed Hubble image, the astronomers also used Hubble's Near Infrared Camera and Multi-Object Spectrometer instrument to try to determine the chemical make-up of the nebula.


In general, where there are clumps of dust, stars can sprout up as the material collapses inward due to gravity. Over time if the clump gets massive enough, it ignites nuclear fusion, at which point a full-fledged star is born. And so the results could also add to knowledge of star birth.

World's Largest Milky Way Image Unveiled

The world's largest picture of the Milky Way, taken by NASA's Spitzer Space Telescope, is being unveiled today at the Adler Planetarium in Chicago.


The new image is of galactic proportions, covering an area that is 120 feet (37 meters) long, 3 feet (1 meter) tall at its sides and 6 feet (2 meters) tall in the middle, where our galaxy's central bulge is depicted.


The panorama represents the combined effort of two Spitzer survey teams, who used two of the telescope's onboard instruments, the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer.


The large image was made from stitching together 800,000 individual pictures taken by Spitzer, for a total of 2.5 billion infrared pixels. It covers an area of the sky about as wide as a pointer finger and as long as the length of arms outstretched, which might sound small, but covers about half of the entire galaxy, says Robert Hurt, of the Spitzer Science Center at Caltech.


"This is the highest-resolution, largest, most sensitive infrared picture ever taken of our Milky Way," said Sean Carey of the Spitzer Science Center, who led one of the teams that created the image.


"I suspect that Spitzer's view of the galaxy is the best that we'll have for the foreseeable future. There is currently no mission planned that has both a wide field of view and the sensitivity needed to probe the Milky Way at these infrared wavelengths," said Barbara Whitney of the Space Science Institute in Madison, Wis., also part of one of the Spitzer teams.


The image is set to be unveiled by the scientists who created it at 3 p.m. EST at Chicago's Adler Planetarium.

Huge Explosion Reveals the Most Massive Star Known

All supernova explosions are violent affairs, but this one takes the cake. Astronomers have spotted a new type of extremely bright cosmic explosion they think originates from an exceptionally massive star.

This breed of explosion has been long predicted, but never before seen. Like all supernovas, the blast is thought to have marked the end of a star's life. But in this case, that star may have started out with 200 times the mass of the sun.

The supernova in question, SN2007bi, was observed in 2007 in a nearby dwarf galaxy. Scientists knew at once it was something different because it was about 50 to 100 times brighter than a typical supernova.

"It was much brighter, and it was bright for a very long time," said researcher Paolo Mazzali of the Max-Planck Institute for Astrophysics in Germany. "We could observe this thing almost two years after it was discovered, where you normally don't see anything anymore."

After analyzing its signature, astronomers published a paper in the Dec. 3 issue of the journal Nature confirming that it matches theoretical predictions of a so-called pair-instability supernova.

"There were some doubts that they existed," said astronomer Norbert Langer of the University of Bonn in Germany, who did not work on the project. Langer wrote an opinion essay on the finding in the same issue of Nature. "There were severe doubts that stars that massive could ever form in the universe. Now we seem to be very sure that there was a star with 200 solar masses."

In a pair-instability supernova, the star has neared the end of its life and exhausted its main supplies of hydrogen and helium, leaving it a core of mostly oxygen. In smaller stars, the core continues to burn until eventually it is all iron, then collapses in a Type II supernova, leaving behind a remnant black hole or neutron star.

But in the case of an extremely massive star, while its core is still made of oxygen, it releases photons that are so energetic, they create pairs of electrons and their anti-matter opposites, positrons. When the matter and antimatter meet, they annihilate each other. This reaction reduces the star's pressure, and it collapses, igniting the oxygen core in a runaway nuclear explosion that eats up the whole star, leaving no remnant at all.

The discovery of this rare type of supernova suggests that a few stars actually can grow into such large behemoths — which has long been a topic of debate.

"I was never a believer in very massive stars," Mazzali told SPACE.com. "Seeing something like this explode means these things exist. This is a fairly new development in the formation of stars."

JPL Wallpaper: Our Space Meets Yours

If you can't afford a trip to space, JPL Wallpapers can at least give you the visual - even while you check your Facebook page. With more than 80 wallpapers to choose from in six different screen resolutions, you can sit poolside at the moon one day and get lost in a Snowflake Cluster the next.

The wallpapers are completely free and easy to set up. Organized into six categories, including Earth, Mars, Saturn, and Stars & Galaxies, the wallpapers include some of JPL's most popular and stunning images and artist's concepts.

They're updated often to include the latest images from missions like Cassini and the Mars Rovers, so you can explore a new part of the universe - and take it with you -- daily.

Visit jpl.nasa.gov/wallpaper to snag your view of space and read instructions on how to apply your JPL Wallpaper.

NASA's Kepler Space Telescope Discovers Five Exoplanets

The full version of this story with accompanying images is at: http://www.jpl.nasa.gov/news/news.cfm?release=2010-001&cid=release_2010-001 PASADENA, Calif. -- NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets, or planets beyond our solar system. Kepler's high sensitivity to both small and large planets enabled the discovery of the exoplanets, named Kepler 4b, 5b, 6b, 7b and 8b. The discoveries were announced Monday, Jan. 4, by members of the Kepler science team during a news briefing at the American Astronomical Society meeting in Washington. "These observations contribute to our understanding of how planetary systems form and evolve from the gas and dust disks that give rise to both the stars and their planets," said William Borucki of NASA's Ames Research Center in Moffett Field, Calif. Borucki is the mission's science principal investigator. "The discoveries also show that our science instrument is working well. Indications are that Kepler will meet all its science goals." Known as "hot Jupiters" because of their high masses and extreme temperatures, the new exoplanets range in size from similar to Neptune to larger than Jupiter. They have orbits ranging from 3.3 to 4.9 days. Estimated temperatures of the planets range from 2,200 to 3,000 degrees Fahrenheit, hotter than molten lava and much too hot for life as we know it. All five of the exoplanets orbit stars hotter and larger than Earth's sun. "It's gratifying to see the first Kepler discoveries rolling off the assembly line," said Jon Morse, director of the Astrophysics Division at NASA Headquarters in Washington. "We expected Jupiter-size planets in short orbits to be the first planets Kepler could detect. It's only a matter of time before more Kepler observations lead to smaller planets with longer-period orbits, coming closer and closer to the discovery of the first Earth analog." Launched on March 6, 2009, from Cape Canaveral Air Force Station in Florida, the Kepler mission continuously and simultaneously observes more than 150,000 stars. Kepler's science instrument, or photometer, already has measured hundreds of possible planet signatures that are being analyzed. While many of these signatures are likely to be something other than a planet, such as small stars orbiting larger stars, ground-based observatories have confirmed the existence of the five exoplanets. The discoveries are based on approximately six weeks' worth of data collected since science operations began on May 12, 2009. Kepler looks for the signatures of planets by measuring dips in the brightness of stars. When planets cross in front of, or transit, their stars as seen from Earth, they periodically block the starlight. The size of the planet can be derived from the size of the dip. The temperature can be estimated from the characteristics of the star it orbits and the planet's orbital period. Kepler will continue science operations until at least November 2012. It will search for planets as small as Earth, including those that orbit stars in a warm, habitable zone where liquid water could exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at least three years to locate and verify an Earth-size planet. According to Borucki, Kepler's continuous and long-duration search should greatly improve scientists' ability to determine the distributions of planet size and orbital period in the future. "Today's discoveries are a significant contribution to that goal," Borucki said. "The Kepler observations will tell us whether there are many stars with planets that could harbor life, or whether we might be alone in our galaxy." Kepler is NASA's 10th Discovery mission. NASA Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., was responsible for developing the Kepler flight system. Ball and the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder are supporting mission operations. The California Institute of Technology in Pasadena manages JPL for NASA. Ground observations necessary to confirm the discoveries were conducted with ground-based telescopes: the Keck I in Hawaii; Hobby-Ebberly and Harlan J. Smith 2.7m in Texas; Hale and Shane in California; WIYN, MMT and Tillinghast in Arizona; and Nordic Optical in the Canary Islands, Spain. For more information about the Kepler mission, visit http://www.nasa.gov/kepler .