Hubble Telescope Captures Heavenly Vision of Lagoon Nebula

By SPACE.com Staff

A majestic new image from the Hubble Space Telescope reveals billowing waves of glowing gas and dust at the heart of a bright and active star-forming nebula in deep space.

The delicate-looking clouds in the Lagoon Nebula are sculpted by the intense radiation from hot young stars. [New Photo of the Lagoon Nebula]

The whirls of hydrogen gas are slowly collapsing to form stars, whose bright ultraviolet rays illuminate the surrounding gas in a distinctive shade of red.

The wispy tendrils and crashing wave-like features are caused by ultraviolet radiation's ability to erode and disperse the gas and dust into the distinctive shapes that are visible in the image.

Hubble's Advanced Camera for Surveys captured the dramatic view of the Lagoon Nebula.

The Lagoon Nebula is located more than 4,000 light-years away from Earth, in the constellation Sagittarius (the Archer). It is a vast stellar nursery that stretches about 100 light-years wide. One light-year is the distance light travels in one year, about 6 trillion miles (9.7 trillion kilometers).

This hotbed of star formation earned its name because of a wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula. The structure is prominent in wide-field images, but cannot be seen in this new close-up.

In recent years, astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous proof that star formation by accretion of matter from the gas cloud is ongoing in this region.

Young stars that are still surrounded by an accretion disk will occasionally shoot out long wisps of matter from their poles.

Evidence of these jets, which are called Herbig-Haro objects, have been found in the Lagoon Nebula in the last five years, which provides strong support for astronomers' theories about star formation in such hydrogen-rich regions.

The Lagoon Nebula has been observed by astronomers for centuries, so the new Hubble photo is the latest in a long line of observations. In the 18th century, French astronomer Charles Messier included the object in his famous astronomical catalogue, dubbing the nebula with an alternate name: Messier 8.

Odds of Life on Newfound Earth-Size Planet '100 Percent,' Astronomer Says

By Jeanna Bryner


An Earth-size planet has been spotted orbiting a nearby star at a distance that would makes it not too hot and not too cold — comfortable enough for life to exist, researchers announced today (Sept. 29).
If confirmed, the exoplanet, named Gliese 581g, would be the first Earth-like world found residing in a star's habitable zone — a region where a planet's temperature could sustain liquid water on its surface

And the planet's discoverers are optimistic about the prospects for finding life there.
"Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent," said Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz, during a press briefing today. "I have almost no doubt about it."
His colleague, Paul Butler of the Carnegie Institution of Washington, in Washington, D.C., wasn't willing to put a number on the odds of life, though he admitted he's optimistic.

"It's both an incremental and monumental discovery," Sara Seager, an astrophysicist at the Massachusetts Institute of Technology, told SPACE.com. Incremental because the method used to find Gliese 581g already has found several planets (all super-Earths, more massive than our own world) outside their stars' habitable zone, along with non-Earth-like planets within the habitable zone.

"It really is monumental if you accept this as the first Earth-like planet ever found in the star's habitable zone," said Seager, who was not directly involved in the discovery.

Vogt, Butler and their colleagues will detail the planet finding in the Astrophysical Journal.

The newfound planet joins more than 400 other alien worlds known to date. Most are huge gas giants, though several are just a few times the mass of Earth.

Stellar tugs

Gliese 581g is one of two new worlds the team discovered orbiting the red dwarf star Gliese 581, bumping that nearby star's family of planets to six. The other newfound planet, Gliese 581f, is outside the habitable zone, researchers said.

The star is located 20 light-years from Earth in the constellation Libra. One light-year is about 6 trillion miles (10 trillion km).

Red dwarf stars are about 50 times dimmer than our sun. Since these stars are so much cooler, their planets can orbit much closer to them and still remain in the habitable zone.

Estimates suggest Gliese 581g is 0.15 astronomical units from its star, close enough to its star to be able to complete an orbit in just under 37 days. One astronomical unit is the average distance between the Earth and sun, which is approximately 93 million miles (150 million km).
The Gliese 581 planet system now vaguely resembles our own, with six worlds orbiting their star in nearly circular paths.

With support from the National Science Foundation and NASA, the scientists — members of the Lick-Carnegie Exoplanet

Survey — collected 11 years of radial velocity data on the star. This method looks at a star's tiny movements due to the gravitational tug from orbiting bodies.

The subtle tugs let researchers estimate the planet's mass and orbital period, how long it takes to circle its star.

Gliese 581g has a mass three to four times Earth's, the researchers estimated. From the mass and size, they said the world is probably a rocky planet with enough gravity to hold onto an atmosphere.

Just as Mercury is locked facing the sun, the planet is tidally locked to its star, so that one side basks in perpetual daylight, while the other side remains in darkness. This locked configuration helps to stabilize the planet's surface climate, Vogt said.

"Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude," Vogt said, suggesting that life forms that like it hot would just scoot toward the light side of that line while forms with polar-bear-like preferences would move toward the dark side.

Between blazing heat on the star-facing side and freezing cold on the dark side, the average surface temperature may range from 24 degrees below zero to 10 degrees Fahrenheit (minus 31 to minus 12 degrees Celsius), the researchers said.

Are you sure?

Supposedly habitable worlds have been found and later discredited, so what makes this one such a breakthrough?

There's still a chance that further observations will dismiss this planet, also. But over the years, the radial velocity method has become more precise, the researchers point out in their journal article.

In addition, the researchers didn't make some of the unrealistic assumptions made in the past, Seager said.

For instance, another planet orbiting Gliese 581 (the planet Gliese 581c) also had been considered to have temperatures suitable for life, but in making those calculations, the researchers had come up with an "unrealistic" estimate for the amount of energy the planet reflected, Seager pointed out. That type of estimate wasn't made for this discovery.

"We're looking at this one as basically the tip of the iceberg, and we're expecting more to be found," Seager said.

One way to make this a reality, according to study researchers, would be "to build dedicated 6- to 8-meter-class Automated Planet Finder telescopes, one in each hemisphere," they wrote.

The telescopes — or "light buckets" as Seager referred to them — would be dedicated to spying on the nearby stars thought to potentially host Earth-like planets in their habitable zones. The result would be inexpensive and probably would reveal many other nearby potentially habitable planets, the researchers wrote.

Beyond the roughly 100 nearest stars to Earth, there are billions upon billions of stars in the Milky Way, and with that in mind, the researchers suggest tens of billions of potentially habitable planets may exist, waiting to be found.

Planets like Gliese 581g that are tidally locked and orbit the habitable zone of red dwarfs have a high probability of harboring life, the researchers suggest.

Earth once supported harsh conditions, the researchers point out. And since red dwarfs are relatively "immortal" living hundreds of billions of years (many times the current age of the universe), combined with the fact that conditions stay so stable on a tidally locked planet, there's a good chance that if life were to get a toe-hold it would be able to adapt to those conditions and possibly take off, Butler said.

Celestial Fireworks

By NASA

Like an Independence Day fireworks display, a young, glittering collection of stars looks like an aerial burst. The cluster is surrounded by clouds of interstellar gas and dust -- the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. This environment is not as peaceful as it looks. Ultraviolet radiation and violent stellar winds have blown out an enormous cavity in the gas and dust enveloping the cluster, providing an unobstructed view of the cluster. Most of the stars in the cluster were born around the same time but differ in size, mass, temperature, and color. The course of a star's life is determined by its mass, so a cluster of a given age will contain stars in various stages of their lives, giving an opportunity for detailed analyses of stellar life cycles. NGC 3603 also contains some of the most massive stars known. These huge stars live fast and die young, burning through their hydrogen fuel quickly and ultimately ending their lives in supernova explosions. Star clusters like NGC 3603 provide important clues to understanding the origin of massive star formation in the early, distant universe. Astronomers also use massive clusters to study distant starbursts that occur when galaxies collide, igniting a flurry of star formation. The proximity of NGC 3603 makes it an excellent lab for studying such distant and momentous events. Image Credit: NASA, ESA, R. O'Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young

(Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA)

Springtime for Northern Titan: Seven Years of Clearer Skies

By SPACE.com Staff

The clouds are clearing on Titan as spring takes hold in its northern hemisphere, signaling a shift in the weather patterns on Saturn's largest moon, a new study finds.
Titan is poised for a mostly sunny spring, one that will last seven Earth years, researchers have found. Seasons on Titan last so long because it takes the moon and Saturn about 30 years to orbit the sun. [New photo of Titan clouds.]

Scientists analyzed data from the last six years of observations by NASA's Cassini spacecraft to piece together how Titan's weather cycle works. They found that conditions have changed since August 2009 — when the sun was directly over Titan's equator during its latest equinox.

"The clouds at the south pole completely disappeared just before the equinox, and the clouds in the north are thinning out," study leader Sebastien Rodriguez of the Universite Paris Diderot said in a statement. "We are expecting to see cloud activity reverse from one hemisphere to another in the coming decade as southern winter approaches."

Rodriguez and his colleagues said their findings match predictions by computer models. They presented their results at the European Planetary Science Congress 2010 in Rome on Sept. 22.

On Titan, it rains methane

Titan and its weather have intrigued scientists for decades. Some think Earth resembled Titan before life took hold — only not nearly as cold. Titan's surface averages 290 degrees below zero Fahrenheit (minus 179 degrees Celsius).

Titan has a thick, nitrogen-rich atmosphere, and its surface features have been carved by the action of liquid hydrocarbons like methane, which is the chief component of natural gas here on Earth. Methane rain drizzles from Titan's clouds, pooling in frigid liquid lakes.

To better understand Titan's weather, Rodriguez and his team used data gathered by the Cassini spacecraft since July 2004. They studied about 2,000 cloud images Cassini snapped between then and this past April, when Titan's seven-year spring began in the northern hemisphere.

In Cassini's early images, clouds gather at Titan's north and south poles, as well as in a narrow belt in the southern hemisphere. But in recent images, with the northern spring taking hold, cloud cover has decreased substantially at both poles.

Seasons change on Titan

These findings match predictions by computer models developed by other researchers in the past. Rodriguez and his team combined those models with the actual Titan observations to understand Titan's evolving cloud patterns.

Different cloud-formation mechanisms are likely at work in the different hemispheres, the researchers said.

During the northern winter, ethane and aerosols probably stream down from high in Titan's stratosphere, generating clouds near the north pole. These clouds are made of ethane, and they form at altitudes of 19 to 31 miles (30-50 km).

In the southern summer, on the other hand, methane-rich air wells up from Titan's surface. This action forms methane clouds at middle to high latitudes, the scientists said.

As Titan's seasons turn, these cloud-formation actions and patterns may flip from one hemisphere to the other, the researchers said.

They can see for themselves.

In February the Cassini mission was extended to May 2017, meaning Rodriguez and his team can get cloud-cover data all the way from mid-winter to mid-summer in Titan's northern hemisphere.

"We have learned a lot about Titan's climate since Cassini arrived at Saturn, but there is still a great deal to learn," Rodriguez said. "With the new mission extension, we will have the opportunity to answer some of the key questions about the meteorology of this fascinating moon."

Spectacular Aurora on Saturn Shines in New Video

Earth isn't the only planet in the solar system with a dazzling northern lights show. A new video from Saturn shows spectacular aurora on the ringed planet, revealing new details about how the phenomenon works.
The Saturn aurora movie was made from images collected by NASA's Cassini spacecraft's visual and infrared mapping spectrometer (VIMS) instrument. [Video of Saturn auroras.]

"Cassini's instruments have been imaging the aurora in magnificent detail, but to understand the overall nature of the auroral region we need to make a huge number of observations -- which can be difficult because Cassini observation time is in high demand," said study leader Tom Stallard of the U.K.'s University of Leicester in a statement. "However, there are VIMS observations of numerous other scientific targets that also include auroral information. Sometimes the aurora can be clearly seen, sometimes we have to add multiple images together to produce a signal."


As a whole, the collection of observations should help build up a better understanding of how auroras happen across the solar system, he said.


Stallard will present preliminary results from his study at the European Planetary Science Congress in Rome on Friday (Sept. 24).

In the new Cassini video, the aurora can clearly be seen to vary significantly over the course of a Saturnian day, which lasts around 10 hours and 47 minutes. On the noon and midnight sides (to the left and right respectively) the aurora can be seen to brighten significantly for periods of several hours, suggesting the brightening is connected with the direction of the sun.

Other features can be seen rotating along with the underlying planet, reappearing at the same time and the same place on the second day. This suggests that they are directly controlled by the direction of Saturn's magnetic field, researchers said.

As with Earth's northern and southern lights, the auroras on Saturn are created when solar wind particles are channeled into the planet's magnetic field toward its poles. There, they interact with electrically charged gas (plasma) in the upper atmosphere and emit light.

However, aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet's magnetosphere.

To date, Stallard and his colleagues have investigated some 1,000 images from the 7,000 that Cassini's VIMS instrument has recorded of Saturn's auroral region.

"Saturn's aurorae are very complex and we are only just beginning to understand all the factors involved," Stallard said. "This study will provide a broader view of the wide variety of different auroral features that can be seen, and will allow us to better understand what controls these changes in appearance."

Like Moths to a Flame, Alien Planets Can Flock to Nearest Star

By Denise Chow
A newfound alien solar system with planets the size of Saturn circling close to their star is helping astronomers learn how some giant worlds snuggle up to their stellar parents like moths to a flame.
NASA's Kepler space observatory recently confirmed the presence of the two Saturn-sized planets that orbit a star about 2,300 light-years away from Earth. A third, much smaller planet may also orbit the star, circling so close that one year on the alien world would last just 1.6 Earth days.
While the discovery of the Kepler-9 planetary system is a major find, it is also a starting point for astronomers to learn how the planet arrangement formed in the first place. [Gallery - Strangest Alien Planets]

Scientists think these planets originated much farther from their parent star and gradually migrated inward over time. All three objects could fit inside the orbit of Mercury today.


"It's safe to say that they did migrate because they ended up in this very special set of orbits," said Alycia Weinberger, an astronomer in the department of terrestrial magnetism at the Carnegie Institution of Washington in Washington, D.C., when the planets were announced in late August."

"The likely candidate for how that migration happened is interaction between these planets and the original disk of material – the gas out of which they formed. It will now take some work to try to figure out exactly how that was likely to happen in this system," Weinberger said.

Timing planet paths

Understanding the process of planetary migration will help astronomers understand the initial conditions that led to the final configuration of the Kepler-9 system, and other planetary systems discovered in the future.

As a planetary system is being formed, "planets can change locations or migrate due to interactions with the raw materials with which they are built," Weinberger said.

A study led by Matthew Holman, associate director of the theoretical astrophysics division at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., determined that the two Saturn-sized planets, named Kepler-9b and Kepler-9c, have somewhat atypical orbits.

It takes Kepler-9b about 19.2 days to complete one orbit. The other Saturn-sized world, Kepler-9c, makes one orbit every 38.9 days, taking almost twice as long to complete the circuit.

"There is a near 2-to-1 orbital resonance, which means the planets have orbital periods in a 2-to-1 ratio," Holman told SPACE.com. "At this configuration, we can see that they strongly interact and we can see large variations in the orbits of the planets."

What planetary migration tells us

Studying how planetary migration occurs, and how much a planet has moved, can tell researchers a lot about the history of how such worlds and their local solar system formed.

Kepler-9b and 9c were found to have a lot of gravitational interaction, and they are located so close to their parent star that their orbits would fit inside the orbit of Mercury in our own solar system, said Holman.

The two planets most likely migrated to their observed locations, said Weinberger, because being so close to the star would have made it extremely difficult to develop and survive in the first place.

Observations combined with theoretical work will then be able to pinpoint how far apart the planets originated, how long it took them to form and how long their migration lasted.

"Kepler was designed and built to answer fundamental questions," Weinberger said. "We want to know what types of planetary systems there are; what is common amongst the various systems; whether there are any special conditions that result in Earth-like planets; whether the whole system of planet formation is robust and common

Building Blocks for Life on Mars Possibly Seen By Viking Probes, Study Suggests

Samples of Mars dirt collected by NASA's Viking Mars landers back in the 1970s may have contained carbon-based chemical building blocks of life as we know it, a new study suggests.


During their missions, the two Viking landers vaporized Martian dirt and scrutinized the samples for signs of organic - or carbon-based - molecules that could serve as the raw ingredients for life. At the time, all they found were chlorine compounds attributed to contamination, but the new research suggests the Viking probes' heat-treatment may have generated these chlorine compounds from naturally occurring Martian organics, destroying them in the process.

"This doesn't say anything about the question of whether or not life has existed on Mars, but it could make a big difference in how we look for evidence to answer that question," study co-author Chris McKay, of NASA's Ames Research Center in Moffett Field, Calif., said in a statement.

Organic molecules can come from non-biological or biological sources. Meteorites raining on Mars and Earth for the past 5 billion years contain organics, so even if Mars has never supported life, scientists before the Viking missions expected Martian dirt to contain at least some organics, researchers have said.


New evidence from Phoenix

The new study follows a 2008 discovery made by the Phoenix Mars Lander. In its roughly five months on Mars, Phoenix found a chlorine-containing chemical called perchlorate in the Martian dirt.

In the lab, the research team for the new study added perchlorate to some desert dirt from Chile that was known to contain organics. Then they heated the soil up, mimicking the Viking landers' organics-detection test. They found the same two organic chlorine compounds the Vikings did: chloromethane and dichloromethane.

What's the connection between these three chemicals? Perchlorate becomes a strong oxidant when heated, breaking down naturally occurring organics into chloromethane and dichloromethane.

"Our results suggest that not only organics, but also perchlorate, may have been present in the soil at both Viking landing sites," the study's lead author, Rafael Navarro-González of the National Autonomous University of Mexico, said in a statement.

"[Perchlorate] could sit there in the Martian soil with organics around it for billions of years and not break them down, but when you heat the soil to check for organics, the perchlorate destroys them rapidly," McKay said.

Challenging old theories

The new study, in the current issue of the Journal of Geophysical Research – Planets, may inspire scientists to reconsider the results of the Viking mission.

The Viking landers performed several different tests on Martian surface material in 1976. They found no compelling evidence for life, or even for the existence of organic molecules.

But subsequent studies have questioned what these tests actually showed. Researchers replicating Viking's methods on Earth, for example, failed to detect signs of life in Earth soil teeming with microbes.

More than three decades ago, the two Viking landers scooped up some Martian dirt and heated it to 500 degrees Celsius (932 degrees Fahrenheit). The chlorine compounds they found were interpreted at the time as contaminants from cleaning fluids.

"The lack of organics was a big surprise from the Vikings," McKay said. "But for 30 years we were looking at a jigsaw puzzle with a piece missing. Phoenix has provided the missing piece: perchlorate. The perchlorate discovery by Phoenix was one of the most important results from Mars since Viking."

Trying to resolve the question

Upcoming Mars missions and further work on meteorites from Mars could help resolve whether Viking actually found evidence of organics on the Red Planet.



Curiosity, a rover that NASA's Mars Science Laboratory mission will deliver to Mars in 2012, will range far and wide, analyzing a broad range of rocks and dirt samples. Its instruments will check for organics in Martian dirt and powdered rocks by baking samples to even higher temperatures than Viking did and by using an alternative liquid-extraction method at much lower heat.

Combining these techniques on a range of samples may help test the new study's idea that heated-up perchlorates could have destroyed organics in the Viking tests.

The European-led ExoMars mission, set to launch in 2018, will include a rover with the ability to dig about 6.5 feet (2 meters) below the Martian surface. The chances of finding complex molecules, including evidence of life such as proteins, are better underground, where molecules are protected from harsh ultraviolet radiation.

Starburst Galaxy Unleashes Gassy 'Superwind'

A striking galaxy buzzing with energetic star formation takes center stage in a new photograph that showcases an unusual "superwind" of out-flowing gas, researchers say.

The starburst galaxy NGC 4666, located about 80 million light-years away from Earth, is a hotbed of intense star formation, which is thought to be caused by gravitational interactions between NGC 4666 and its neighboring galaxies, one of which is visible in the lower left of the new photo. [See the galaxy NGC 4666 photo]

Gravitational interactions between galaxies often trigger the type of rigorous star formation seen in NGC 4666.

Strong winds from the massive stars inside NGC 4666, combined with supernova explosions, drive a robust flow of gas – a so-called "superwind" – from the galaxy into space, according to the European Southern Observatory where astronomers took the new photo.

The superwind originates in the bright central region of the galaxy and extends for tens of thousands of light-years. Astronomers think the cosmic wind could be blowing at speeds of up to a few thousands of kilometers every second, said astronomer Jörg Dietrich of the University of Michigan. The new photo of the galaxy was part of follow-up observations for an earlier study by Dietrich and his colleagues.

"Observing superwinds directly is difficult because the gas in them is very tenuous," Dietrich told SPACE.com in an e-mail. "However, these winds push denser and colder gas out, which is easier to observe."

The gas is very hot and emits radiation mostly in the form of X-rays and in the radio part of the spectrum, which cannot be seen in visible light images.

This new image of NGC 4666 was made in visible light with the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile, which is part of the European Southern Observatory.

The galaxy had previously been observed in X-rays by the European Space Agency's XMM-Newton space telescope, and this image was taken to allow further study of other objects that had been detected in the earlier X-ray observations.

One such object is a faint galaxy cluster that can be seen close to the bottom edge of the image, to the right of center. This cluster, serendipitously found from the XMM-Newton observations, is much farther away from Earth than NGC 4666, at a distance of about 3 billion light-years.

In studying astronomical objects, researchers must observe them at several wavelengths, as light at different wavelengths can show different physical processes that are taking place.

Guts of Exploded Star Revealed

A wave of "star guts" ejected into space from the supernova explosion of a massive dying star has been spotted by the Hubble Space Telescope.

The new supernova image allows astronomers to measure the velocity and composition of the former star's debris, which scientists are calling cosmic "guts," as it interacts with the surrounding environment. [Photo of the supernova star guts.]

The new study, led by Kevin France, a research associate at the Center for Astrophysics and Space Astronomy at the University of Colorado in Boulder, targeted the remnants of Supernova 1987A, which was first discovered in 1987.

France and his colleagues observed the interaction between the stellar explosion and the circumstellar material around the former star – forming what looks like a "string of pearls." A new video of SN1987A illustrates the odd formation.

The glowing ring of gas that measures 6 trillion miles (9.6 trillion km) in diameter encircles the supernova remnant and is energized by X-rays. These "pearls" of circumstellar material are made up of material that was emitted before the star exploded, as it was preparing to die.

The shock waves from the supernova have been brightening some 30 to 40 pearls in the ring. As the stellar debris interacts with the circumstellar material over time, the pearls will eventually form a continuous glowing circle around the remnant.

SN1987A is about 150,000 light-years away from Earth on the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, the nearest galaxy to our own Milky Way.

The age of the original star that set off the explosion remains unclear, but is estimated to be between 5 million and 10 million years.

Analyzing supernovas is important because their intense energy may also trigger much larger cosmic interactions, and could be responsible for regulating the physical state and long-term evolution of galaxies, France said.

"In the big picture, we are seeing the effect a supernova can have in the surrounding galaxy, including how the energy deposited by these stellar explosions changes the dynamics and chemistry of the environment," said he added. "We can use this new data to understand how supernova processes regulate the evolution of galaxies."