Astronomers: Earth's 'bigger cousin' detected

By Michael Schirber SPACE.com
Monday, June 13, 2005 Posted: 3:17 PM EDT (1917 GMT)

(SPACE.com) -- Astronomers announced Monday the discovery of the smallest planet so far found outside of our solar system.
About seven-and-a-half times as massive as Earth, and about twice as wide, this new extrasolar planet may be the first rocky world ever found orbiting a star similar to our own.
"This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets," said team member Paul Butler of the Carnegie Institution of Washington. "It's like Earth's bigger cousin."
Currently around 150 extrasolar planets are known, and the number continues to grow. But most of these far-off worlds are large gas giants like Jupiter. Only recently have astronomers started detecting smaller massed objects
"We keep pushing the limits of what we can detect, and we're getting closer and closer to finding Earths," said team member Steven Vogt from the University of California, Santa Cruz.
The discovery of Earth's distant cousin was announced Monday at a press conference at the National Science Foundation in Arlington, Virginia.
The new planet orbits Gliese 876, an M dwarf star 15 light years away in the constellation Aquarius. The "super-Earth" is not alone: there are two other planets -- both Jupiter-sized -- in the same system. This third world was detected by a tiny extra wobble that it caused in the central star.
From this wobble, the researchers measured a minimum mass for the new planet of 5.9 Earth masses. The planet orbits makes a full orbit in a speedy 1.94 days, implying a distance to the central star of 2 million miles -- or about 2 percent of the distance between the Earth and the Sun.
Orbiting so close to its star, scientists speculate that the planet's temperature is a toasty 400 to 750 degrees Fahrenheit (200 to 400 degrees Celsius). This is likely too hot for the planet to retain much gas, like Jupiter does. Therefore, the planet must be mostly solid.
"The planet's mass could easily hold onto an atmosphere," said Gregory Laughlin from UC Santa Cruz. "It would still be considered a rocky planet, probably with an iron core and a silicon mantle. It could even have a dense steamy water layer."
A paper detailing these results has been submitted to The Astrophysical Journal.

Andromeda galaxy larger than thought

WASHINGTON (Reuters) -- The Andromeda galaxy just got bigger -- three times bigger, astronomers said on Monday.
The galaxy is not actually expanding. But new measurements suggest that the nearest galaxy to our own Milky Way is three times broader than astronomers had thought.
They now believe a thin sprinkling of stars once thought to be a halo is in fact part of Andromeda's main disk.
That makes the spiral galaxy, so close to Earth that it appeared as a fuzzy blob to the ancients, more than 220,000 light-years across -- triple the previous estimate of 70,000 to 80,000 light-years.
It appears that the outer fringes of the disk were made when smaller galaxies slammed together, they told a meeting of the American Astronomical Society in Minneapolis.
The structure is too bumpy to have been formed otherwise, said Rodrigo Ibata of the Observatoire Astronomique de Strasbourg in France.
"This giant disk discovery will be very hard to reconcile with computer simulations of forming galaxies. You just don't get giant rotating disks from the accretion of small galaxy fragments," Ibata said in a statement.
Ibata, Scott Chapman of the California Institute of Technology and colleagues in Britain and Australia worked together using observations from the Keck II telescope in Hawaii.
They studied the motions of about 3,000 stars thought to be a mere halo and not an actual part of the galaxy's disk.
But they are in fact sited in the plane of the Andromeda disk itself and move at a velocity that suggests they are in orbit around the center of the galaxy, Ibata's team said.
Andromeda is 2 million light-years from Earth. A light-year is the distance light travels in a year -- about 6 trillion miles (10 trillion km).

Bright spot on Titan baffles scientists

Scientists believe the spot might have formed recently as a result of an asteroid impact, landslide or volcanic eruption.
Another Titan flyby in July could determine exactly what the spot is.
Cassini has observed other patches on Titan's surface that usually disappear after a few hours.
The $3.3 billion Cassini mission, funded by NASA and the European and Italian space agencies, was launched in 1997 and took seven years to reach Saturn to explore the ringed planet and its moons.
Scientists think Titan's atmosphere is similar to that of the early Earth and studying it could provide clues to how life began here.
Cassini is managed by NASA's Jet Propulsion Laboratory in Pasadena.

NASA seeks oxygen source on moon

(CNN) -- NASA has offered a $250,000 prize to any scientist who discovers a way of extracting breathable oxygen from moondust.
The competition is the latest in NASA's "Centennial Challenges" series, which aims to stimulate the development of technologies useful to space exploration.
To claim the MoonROx prize, scientists must develop and demonstrate hardware capable of extracting at least five kilograms of breathable oxygen from a simulated lunar soil made from volcanic ash in an eight-hour period.
MoonROx stands for Moon Regolith Oxygen -- regolith being the loose layer of rocks and debris covering the surface of a planet or moon.
The MoonROx Challenge was announced by NASA in partnership with the Florida Space Research Institute (FSRI). Entrants have until June 1 2008 to collect the prize fund.
Craig Steidle of NASA's exploration office said that the use of resources on other worlds was a key element in the organization's vision of space exploration.
It hopes the prize could lead to the development of a sustainable source of oxygen that could support permanent lunar bases and provide the fuel for vehicles that will land on and launch from the moon.
Unveiling a new vision of NASA-led space exploration last year, U.S. president George W. Bush said that a moon colony could be used as a "stepping stone" for missions into deeper space.
Bush said the soil of the moon contained "raw materials that might be harvested and processed into rocket fuel or breathable air. With the experience and knowledge gained on the moon, we will then be ready to take the next steps of space exploration -- human missions to Mars and to worlds beyond."
While ways of extracting oxygen from regolith already exist, so far nobody has come close to producing the large quantities that would be needed by NASA.
"Oxygen extraction technologies will be critical for both robotic and human missions to the moon," said FSRI Executive Director Sam Durrance, a former astronaut.
"Like other space-focused prize competitions, the MoonROx challenge will encourage a broad community of innovators to develop technologies that expand our current capabilities."
NASA launched the Centennial Challenges in March in the spirit of past competitions that have fostered technical innovation in the aviation and space industries. In October SpaceShipOne claimed the $10 million X-Prize after becoming the first privately funded spacecraft to successfully reach sub-orbital space.
The first two challenges focused on developing technologies towards building a space elevator that could put satellites into orbit.
"For more than 200 years, prizes have played a key role in spurring new achievements in science, technology, engineering and exploration," said NASA's Associate Administrator for Exploration Systems Mission Directorate, Craig Steidle.
"The innovations from these competitions will help support advances in aerospace materials and structures, new approaches to robotic and human planetary surface operations, and even futuristic concepts like space elevators and solar power satellites."

New planet found in Milky Way

New planet found in Milky Way

(CNN) -- Australasian researchers have helped discover a new planet in the Milky Way, and they believe it's just a matter of time before more are discovered.
The gaseous planet is about 1000 times the size of Earth and is about halfway to the center of the galaxy, or about 25,000 light years away, researchers said Tuesday.
The project used a little-known technique called micro-lensing -- using the gravitational pull of a star to act as a giant lens -- to help astronomers to look for new planets.
University of Tasmania Professor John Dickey, who took part in the project, told Australia's ABC radio that that the technique could help astronomers discover new planets unable to be picked up by more traditional methods.
"What's special about this event is, it was discovered in a way ... which could, in principle, turn up Earth-like planets as well," Dickey said.
"Our other ways of finding planets around stars are only sensitive to very massive ones like Jupiter.
"We've been struggling with this technique to try to open the door to finding Earth-like planets, which I think is now much more hopeful."
The Hubble Telescope in the United States will now be used to try to find out more information about the star and its planet, which astronomers believe is the most distant ever detected.
The discovery is the result of a project coordinated by the Paris Institute of Astrophysics involving four telescopes in the southern hemisphere, including the University of Tasmania's Canopus Observatory.

Images show strange steep slopes on Mars

(SPACE.com) -- New images of Mars show fresh detail of steep and inexplicable slopes.

The Medusa Fossae formation is an extensive area of unknown origin found near a boundary between the highlands and lowlands of Mars. It straddles the Tharsis and Elysium centers of volcanic activity.

This dichotomy boundary is a narrow region separating the cratered highlands, located mostly in the southern hemisphere of the red planet, from the northern hemisphere's lowland plains.

The cratered highlands stand 1.2 -- 3.1 miles (2 -- 5 kilometers) above the lowland plains, so the boundary is a relatively steep slope.

The processes that created and modified the boundary remain a major unanswered issues in Mars science, say scientists with the European Space Agency, which released the Mars Express orbiter images last week.

Scientists think the materials that formed Medusa Fossae were deposited by volcanic fireworks known as pyroclastic flows or similar volcanic ash falls. The plateau walls of the volcanic massif are partly covered by lava flows and crossed in places by valleys which were most likely carved by fluvial activity.

The remains of water-bearing inner channels are visible in the center of the valleys and at the bottom of the massif. Superposition of the lobe-fronted pyroclastic flows indicates that the water erosion ended before their deposition, the European scientists said.

Later, a space rock hit near the massif and an ejecta blanket was spread as a flow over parts of the plateau, implying water or ice was present in the subsurface at the time of impact.

Astronomers capture photo of extrasolar planet

'First directly imaged and confirmed companion to a sun-like star'

By Robert Roy BrittSPACE.comFriday, April 1, 2005 Posted: 1:40 PM EST (1840 GMT)

(SPACE.com) -- After a few close calls, astronomers have finally obtained the first photograph of a planet beyond our solar system, SPACE.com has learned.
The planet is thought to be one to two times as massive as Jupiter. It orbits a star similar to a young version of our sun.
The star, GQ Lupi, has been observed by a team of European astronomers since 1999. They have made three images using the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile.
The Hubble Space Telescope and the Japanese Subaru Telescope each contributed an image, too.
The work was led by Ralph Neuhaeuser of the Astrophysical Institute & University Observatory (AIU).
"The detection of the faint object near the bright star is certain," Neuhaeuser told SPACE.com on Friday.
The system is young, so the planet is rather warm, like a bun fresh out of the oven. That warmth made it comparatively easier to see in the glare of its host star compared with more mature planets. Also, the planet is very far from the star -- about 100 times the distance between Earth and the Sun, another factor in helping to separate the light between the two objects.
The discovery will be detailed in an upcoming issue of the journal Astronomy & Astrophysics. Neuhaeuser's co-authors include Ph.D. student Markus Mugrauer, who performed the observations, and Guenther Wuchterl.
"This is the first directly imaged and confirmed companion to a sun-like star, and as such marks the dawn of a new era in planet detection," said Ray Jayawardhana, a University of Toronto researcher who was not involved in the discovery but has seen the scientific paper.
Other recent milestones
Over the past decade, astronomers have found about 150 extrasolar planets. The vast majority have only been detected indirectly, by noting their stars' wobbles.
Earlier this month, astronomers announced the detection of a planet's infrared light using the Spitzer Space Telescope. But that observation did not involve a photograph. Instead, the system's total light was seen to drop when the planet was eclipsed by the star.
Late last year, another European team announced what might have been the first photograph of an extrasolar planet. That planet candidate has yet to be confirmed, however, because it's not yet clear whether it is orbiting the star or if it might be an object in the distant background. And even if it is a planet, it is an unusually large one -- several times the mass of Jupiter -- and it orbits a failed star known as a brown dwarf.
The object around GQ Lupi is clearly linked to the star gravitationally.
"The separation between star and planet has not changed from 1999 to 2004, which means that they move together on the sky," Neuhaeuser said. "In our case, we do have a normal plain image showing the bright star and the faint planet a little bit west of the star. The planet is only 156 times fainter than the star, because the planet is still very young and hence still forming, still contracting."
This object "appears to pass" the observational tests "for being a planetary mass companion to its parent star," Jayawardhana said.
Familiar yet different
The picture of GQ Lupi and its planet is exciting to astronomers because the system resembles in some respects our own solar system in its formation years.
The planet is about 3,140 degrees Fahrenheit (2000 Kelvin) -- not the sort of place that would be expected to support life. Neuhaeuser's team has also detected water in the planet's atmosphere. The world is expected to be gaseous, like Jupiter. It is about twice the diameter of Jupiter. The mass estimate -- one to two times that of Jupiter -- is "somewhat uncertain," Neuhaeuser said.
The planet is three times farther from GQ Lupi than Neptune is from our Sun. "We should expect that the planet orbits around the star, but at its large separation one orbital period [a year] is roughly 1,200 years, so that orbital motion is not yet detected."
It's not known why it is so far out.
"It is unlikely, but not impossible, that the planet formed at that large separation, because circumstellar disks around other stars often are that large or even larger," Neuhaeuser said.
Or perhaps the planet had a close brush with another developing world. The interaction could have thrown the newly discovered planet outward while tossing the other one, which has not been detected, in toward the star. It's also possible the newfound planet has a highly elliptical orbit and is currently near its outer bounds.
The star GQ Lupi is part of a star-forming region about 400 light-years away. At 70 percent the mass of the Sun, it is "quite similar to our Sun," Neuhaeuser said. But GQ Lupi is only about 1 million years old. The Sun is middle-aged, at 4.6 billion years old.
Quick formation
"What's most exciting about this discovery is that it raises a plethora of new questions regarding the origin of a planet so far out from its parent star," Jayawardhana, who is an expert on the disks around young stars from which planets form, said in a email interview.
Jayawardhana wonders whether it formed in a protoplanetary disk much closer in, roughly where Jupiter is in our solar system, and then get flung out. Or if it was born almost at the same time as its star, fragmenting out of a contracting protostellar cloud.
"One way or another, this object must have formed pretty quickly" given the star's age, he said.
Knots of gas and dust have been detected around other young stars in setups that astronomers believe are solar systems in the making. Theorists believe our solar system formed when the Sun's leftovers developed into a thin disk of orbiting material.
Rocky planets like Earth formed when chunks stuck together. Astronomers do not agree, however, how gas giants are born.
Alan Boss, a planet formation theorist at Carnegie Institution of Washington, called the image "really exciting." But he said there is "one little nagging doubt" in that the object's mass is only an estimate.
Weighing it precisely would involve noting the gravitational wobble the apparent planet induces on the star, but this object is too far from the star to produce a meaningful wobble. Yet even if the object is four times the mass of Jupiter it would still be considered a planet, Boss said in a telephone interview.
"I think there's a really good chance that this is an historic photo," Boss said.

Rainbows On Titan

Titan might be the only other place in our solar system that has rainbows.

Rainbows On Titan!

by Dr Tony Phillips

When the European Space Agency's Huygens probe visited Saturn's moon Titan last month, the probe parachuted through humid clouds. It photographed river channels and beaches and things that look like islands.
Finally, descending through swirling fog, Huygens landed in mud. To make a long story short, Titan is wet.
Christian Huygens wouldn't have been a bit surprised. In 1698, three hundred years before the Huygens probe left Earth, the Dutch astronomer wrote these words:
"Since 'tis certain that Earth and Jupiter have their Water and Clouds, there is no reason why the other Planets should be without them. I can't say that they are exactly of the same nature with our Water; but that they should be liquid their use requires, as their beauty does that they be clear.
"This Water of ours, in Jupiter or Saturn, would be frozen up instantly by reason of the vast distance of the Sun. Every Planet therefore must have its own Waters of such a temper not liable to Frost."
Huygens discovered Titan in 1655, which is why the probe is named after him. In those days, Titan was just a pinprick of light in a telescope. Huygens could not see Titan's clouds, pregnant with rain, or Titan's hillsides, sculpted by rushing liquids, but he had a fine imagination.
Titan's "water" is liquid methane, CH4, better known on Earth as natural gas. Regular Earth-water, H2O, would be frozen solid on Titan where the surface temperature is 290o F below zero. Methane, on the other hand, is a flowing liquid, of "a temper not liable to Frost."
Jonathan Lunine, a professor at the University of Arizona, is a member of the Huygens mission science team. He and his colleagues believe that Huygens landed in the Titan-equivalent of Arizona, a mostly-dry area with brief but intense wet seasons.
"The river channels near the Huygens probe look empty now," says Lunine, but liquids have been there recently, he believes. Little rocks strewn around the landing site are compelling: they're smooth and round like river rocks on Earth, and "they sit in little depressions dug, apparently, by rushing fluids."
The source of all this wetness might be rain. Titan's atmosphere is "humid," meaning rich in methane. No one knows how often it rains, "but when it does," says Lunine, "the amount of vapor in the atmosphere is many times that in Earth's atmosphere, so you could get very intense showers."
And maybe rainbows, too. "The ingredients you need for a rainbow are sunlight and raindrops. Titan has both," says atmospheric optics expert Les Cowley.
On Earth, rainbows form when sunlight bounces in and out of transparent water droplets. Each droplet acts like a prism, spreading light into the familiar spectrum of colors. On Titan, rainbows would form when sunlight bounces in and out of methane droplets, which, like water droplets, are transparent.
"Their beauty [requires] that they be clear...."
"A methane rainbow would be larger than a water rainbow," notes Cowley, "with a primary radius of at least 49o for methane vs 42.5o for water. This is because the index of refraction of liquid methane (1.29) differs from that of water (1.33)."
The order of colors, however, would be the same: blue on the inside and red on the outside, with an overall hint of orange caused by Titan's orange sky.
One problem: Rainbows need direct sunlight, but Titan's skies are very hazy. "Visible rainbows on Titan might be rare," says Cowley. On the other hand, infrared rainbows might be common.
Atmospheric scientist Bob West of NASA's Jet Propulsion Laboratory explains: "Titan's atmosphere is mostly clear at infrared wavelengths. That's why the Cassini spacecraft uses an infrared camera to photograph Titan."
Infrared sunbeams would have little trouble penetrating the murky air and making rainbows. The best way to see them: infrared "night vision" goggles.
All this talk of rain and rainbows and mud makes liquid methane sound a lot like ordinary water. It's not. Consider the following:
The density of liquid methane is only about half the density of water. This is something, say, a boat builder on Titan would need to take into account. Boats float when they're less dense than the liquid beneath them.
A Titan-boat would need to be extra lightweight to float in a liquid methane sea. (It's not as crazy as it sounds. Future explorers will want to visit Titan and boats could be a good way to get around.)
Liquid methane also has low viscosity (or "gooiness") and low surface tension. See the table below. Surface tension is what gives water its rubbery skin and, on Earth, lets water bugs skitter across ponds.
A water bug on Titan would promptly sink into a pond of flimsy methane. On the bright side, Titan's low gravity, only one-seventh Earth gravity, might allow the creature climb back out again.
Back to boats: Propellers turning in methane would need to be extra-wide to "grab" enough of the thin fluid for propulsion. They'd also have to be made of special materials resistant to cracking at cryogenic temperatures.
And watch out for those waves! European scientists John Zarnecki and Nadeem Ghafoor have calculated what methane waves on Titan might be like: seven times taller than typical Earth-waves (mainly because of Titan's low gravity) and three times slower, "giving surfers a wild ride," says Ghafoor.
Last but not least, liquid methane is flammable. Titan doesn't catch fire because the atmosphere contains so little oxygen - a key ingredient for combustion. If explorers visit Titan one day they'll have to be careful with their oxygen tanks and resist the urge to douse fires with "water."
Infrared rainbows, towering waves, seas beckoning to sailors. Huygens saw none of these things before it plopped down in the mud. Do they really exist?
"...there is no reason why the other Planets should be without them."


http://www.spacedaily.com/news/saturn-titan-05p.html

Image above: A sun-like star grows into its red giant phase, increasing in size and luminosity. Energy in the form of heat can now reach a once-frozen and dead moon. The icy surface quickly melts into liquid water, filling in old craters with warmer seas. The stage is now set for the possible formation of new life.

New Frontier Opens In The Search For Life On Other Planets

Scientists recently discovered a new frontier in the race to find life outside our solar system. Dying red giant stars may bring icy planets back from the dead. Once-frozen planets and moons may provide a new breeding ground for life as their stars enter the last, and brightest, phase of their lives. Previous ideas about the search for extra-solar life had excluded these regions.

An international team of astronomers estimates that the emergence of new life on a planet is possible within the red giant phase. "Our result indicates that searches for life-giving worlds outside our solar system should include planets around old stars," said Dr. Bruno Lopez of the Observatoire de la Cote d'Azur, Nice, France. Lopez and his colleagues estimate that more than 150 red giant stars are close enough - within 100 light years - for upcoming or proposed missions to search for the signatures of life on distant worlds. A light year is the distance light travels in one year, almost six trillion miles!

Location, Location, LocationOne of the secrets of Earth's success in producing life is its location within the sphere of the Sun's habitable zone. This sphere intersects the plane of the solar system to create a special donut-shaped boundary that outlines where water can exist as a liquid in our solar system, a necessity for the development of life. Get too far from the Sun - and it's a lonely icebox. Too close - and the water evaporates into space, never to return again.

While the Earth currently sits well within this donut of life, our Sun is evolving and will one day grow to be a red giant star. Its habitable zone will expand with it, changing the locales where liquid water can splash and life may one day thrive.

Lying just inside the outer limit of our Sun's habitable zone, Mars remains a frozen world today because of its thin atmosphere. However, when the Sun becomes a red giant a few billion years from now, Mars may become the happening place to be. "Mars will be in the habitable zone for a couple billion years, so Martian life may get a second chance," said Dr. William Danchi of NASA's Goddard Space Flight Center, Greenbelt, Md.

In 2003, researchers monitored the amount of ice on Mars during its winter and spring seasons. In some regions, the water-ice content was more than 90% by volume. Scientists suspect that this water used to fill the planet's now-dry lakes and seas. One day in the distant future, the frozen water on Mars may fill these dry basins again and bring forth new life in our solar system.

Red Giants Redefine the Search for Extra-Terrestrial LifeThe same holds true for planets and moons as they orbit their own red giant suns. Billions of years ago, these stars were similar to our Sun. Imagine the events as they unfolded: A Sun-like star explodes into its red giant phase, growing tremendously in size and brightness. Warm rays from the star reach out to a once-frozen and dead moon. The solitary satellite's icy top layer quickly melts into liquid water, which creeps across the surface and fills old dusty craters with warmer seas. The stage is set for the birth of new life in the moon's now-vibrant oceans.

Currently, there are at least 150 red giant stars within 100 light years of Earth and many of them may have orbiting planets capable of supporting life. A new frontier has opened for planet-hunters around the world.

One such endeavor, NASA's Kepler mission, hopes to discover smaller Earth-like planets outside our solar system. Looking for tiny dips in the brightness of a star when a planet crosses in front of it, researchers will observe about 100,000 stars in one small patch of sky for four years. Kepler is set for launch in 2007.

Image above: Our planet lies within the Sun's habitable zone. This donut-shaped boundary outlines where water can exist as a liquid in our solar system, a necessity for the development of life. As the Sun develops into old age, its habitable zone will expand with it, changing the locales where liquid water can splash and life may one day thrive.

Although Mars is now very dry, this sequence illustrates what Mars would look like today if it still had the massive amount of water researchers believe was present at its formation. An elevation map was created from a topographic survey by NASA's Mars Global Surveyor (MGS) spacecraft, and a computer artist filled in the ancient Martian ocean.

In 2003, researchers monitored the amount of water-ice on Mars, which is more than 90% in some areas. This sequence begins with a "true-color" mosaic of Mars from the Viking orbiter and ends with a visualization of water ice concentration, shown in blue, during the Martian summer months.

Researchers estimate that the time required for the emergence of new life fits within the Red Giant phase, adding to the number of stars that may have Earth-like planets orbiting them. The Kepler Mission will look for tiny dips in the brightness of a star when a planet crosses in front of it, known as a transit.

http://www.nasa.gov/vision/universe/starsgalaxies/frozenworlds.html