Thursday, April 26, 2007

Story of the Day-Gliese

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New 'super-Earth' found in space

Astronomers have found the most Earth-like planet outside our Solar System to date, a world which could have water running on its surface.

The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra.

Scientists made the discovery using the Eso 3.6m Telescope in Chile.

They say the benign temperatures on the planet mean any water there could exist in liquid form, and this raises the chances it could also harbour life.

"We have estimated that the mean temperature of this 'super-Earth' lies between 0 and 40 degrees Celsius, and water would thus be liquid," explained Stephane Udry of the Geneva Observatory, lead author of the scientific paper reporting the result.

"Moreover, its radius should be only 1.5 times the Earth's radius, and models predict that the planet should be either rocky - like our Earth - or covered with oceans."

Xavier Delfosse, a member of the team from Grenoble University, added: "Liquid water is critical to life as we know it."

He believes the planet may now become a very important target for future space missions dedicated to the search for extra-terrestrial life.

These missions will put telescopes in space that can discern the tell-tale light "signatures" that might be associated with biological processes.

The observatories would seek to identify trace atmospheric gases such as methane, and even markers for chlorophyll, the pigment in Earth plants that plays a critical role in photosynthesis.

'Indirect' detection

The exoplanet - as astronomers call planets around a star other than the Sun - is the smallest yet found, and completes a full orbit of its parent star in just 13 days.

ndeed, it is 14 times closer to its star than the Earth is to our Sun.

However, given that the host star is smaller and colder than the Sun - and thus less luminous - the planet nevertheless lies in the "habitable zone", the region around a star where water could be liquid.

Gliese 581 C was identified at the European Southern Observatory (Eso) facility at La Silla in the Atacama Desert.

To make their discovery, researchers used a very sensitive instrument that can measure tiny changes in the velocity of a star as it experiences the gravitational tug of a nearby planet.

Astronomers are stuck with such indirect methods of detection because current telescope technology struggles to image very distant and faint objects - especially when they orbit close to the glare of a star.

The Gliese 581 system has now yielded three planets: the new super-Earth, a 15 Earth-mass planet orbiting even closer to the parent star, and an eight Earth-mass planet that lies further out.

Gliese 581 (Digital Sky Survey)
Gliese 581 is much cooler and dimmer than our own Sun
The latest discovery has created tremendous excitement among scientists.

Of the more than 200 exoplanets so far discovered, a great many are Jupiter-like gas giants that experience blazing temperatures because they orbit close to hot stars.

The Gliese 581 super-Earth is in what scientists call the "Goldilocks Zone" where temperatures "are just right" for life to have a chance to exist.

Commenting on the discovery, Alison Boyle, the curator of astronomy at London's Science Museum, said: "Of all the planets we've found around other stars, this is the one that looks as though it might have the right ingredients for life.

"It's 20 light-years away and so we won't be going there anytime soon, but with new kinds of propulsion technology that could change in the future. And obviously we'll be training some powerful telescopes on it to see what we can see," she told BBC News.

"'Is there life anywhere else?' is a fundamental question we all ask."

Professor Glenn White at the Rutherford Appleton Laboratory is helping to develop the European Space Agency's Darwin mission, which will scan the nearby Universe, looking for signs of life on Earth-like planets. He said: "This is an important step in the search for true Earth-like exoplanets.

"As the methods become more and more refined, astronomers are narrowing in on the ultimate goal - the detection of a true Earth-like planet elsewhere.

"Obviously this newly discovered planet and its companions in the Gliese 581 system will become prominent targets for missions like Esa's Darwin and Nasa's Terrestrial planet Finder when they fly in about a decade."

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WASHINGTON: European astronomers have spotted what they say is the most Earth-like planet yet outside our solar system, with balmy temperatures that could support water and, potentially, life.

They have not directly seen the planet, orbiting a red dwarf star called Gliese 581. But measurements of the star suggest that a planet not much larger than the Earth is pulling on it, the researchers say in a letter to the editor of the journal Astronomy and Astrophysics.

"This one is the first one that is at the same time probably rocky, with water, and in a zone close to the star where the water could exist in liquid form," said Stephane Udry of the Geneva Observatory in Switzerland, who led the study.

"We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degC and water would thus be liquid."

Most of the 200 or so planets that have been spotted outside this solar system have been gas giants like Jupiter. But this one is small.

"Its radius should be only 1.5 times the Earth's radius, and models predict that the planet should be either rocky, like our Earth, or covered with oceans," Udry said in a telephone interview.

It appears to have a mass five times that of Earth's.

The research team includes scientists credited with the first widely accepted discovery of a planet outside our solar system, in 1995.

Many teams are looking for planets circling other stars. They are especially looking for those similar to our own, planets that could support life.

That means finding water.

"Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life," Xavier Delfosse, a member of the team from Grenoble University in France, said in a statement.

"On the treasure map of the universe, one would be tempted to mark this planet with an X."

Gliese 581 is among the 100 closest stars to Earth, just 20.5 light-years away in the constellation Libra.

A light-year is the distance light travels in a year, about 10 trillion km.

It is smaller and dimmer than the sun, so the planet can be close to it and yet not be overheated.

"These low-mass stars are the ones where we are going to be able to discover planets in the habitable zone first," said planet-hunter David Bennett of the University of Notre Dame in Indiana, who was not involved in the research.

Bennett cautioned that current temperature alone does not mean water still exists on the planet. It could have burned off ages ago, when the star was hotter than it is now.

Udry's team uses a method known as radial velocity, using the European Southern Observatory telescope at La Silla, Chile.

The same team has identified one larger planet orbiting Gliese 581 already and say they have strong evidence of a third planet with a mass about eight times that of the Earth.

Future missions, perhaps in 20 to 30 years, may be able to block the light from the star and take a spectrographic image of the planets. The colour of the light coming from the planet can give hints of whether water, or perhaps large amounts of plant life, exist there.

BOOKIES have slashed ET's odds after scientists said they'd found an Earth-like planet.

William Hill have cut the chance of proving the existence of extra-terrestrial intelligence from 1000-1 to 100-1.

It comes after the discovery of the planet which orbits the red dwarf star Gliese 581 - 20.5 light-years away in the constellation Libra.

Scientists say the new world lies in the "Goldilocks Zone"- the band around the star where liquid water could exist.

And that raises the possibility of it supporting life.

Hill's spokesman Graham Sharpe said: "We would face an eight-figure payout if it were to be confirmed that intelligent life of extra-terrestrial origin currently exists.

"We felt we had to react to the news that an Earth-like planet which could support intelligent life had been discovered.

"After all, we don't know for sure that intelligent extraterrestrial life has not been discovered, but is being hushed up."

Dr Xavier Delfosse was part of the team of astronomers who found the planet using the European Southern Observatory's telescope in Chile.

He said: "On the treasure map of the universe, one would be tempted to mark this planet with an X."


And Dr Stephane Udry, who led the European team, said: "We have estimated the mean temperature of this super-Earth lies between 0-40C and water would thus be liquid.

"Moreover, its radius should be only 1.5 times the Earth's and models predict the planet should be either rocky or covered with oceans."

The vast majority of planets already discovered orbiting stars outside the Solar System are gas giants the size of Jupiter, or bigger, ruling out the chances of life as we know it.

The latest one is the smallest known outside the Solar System. And it's older than the Sun, raising the possibility that life on the new planet could be more advanced than it is on Earth.

Scientists at SETI - Search for Extra-Terrestrial Life Institute - in the US plan to listen for intelligent signals from the star system.

SETI spokesman Dr Seth Shostak said: "The older the star is, maybe the greater the chance that it has produced something that's clever."

For William Hill to pay out on an ET bet, the Prime Minister has to confirm the existence of intelligent extra-terrestrial life within a year of the wager being placed.

Sharpe added: "We have come a cropper before when, in the early 60s, we offered 1000-1 on man walking on theMoon before 1970.

"We ended up paying out the equivalent of £1million, including £10,000 to the first man to place such a bet, David Threlfall."

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Sunspot-cycle forecast important to life on Earth

WASHINGTON --The peak of the next sunspot cycle is expected in late 2011 or mid-2012 - potentially affecting airline flights, communications satellites and electrical transmissions. But forecasters can't agree on how intense it will be.

A 12-member panel charged with forecasting the solar cycle said Wednesday it is evenly split over whether the peak will be 90 sunspots or 140 sunspots.

The government's Space Environment Center in Boulder, Colo., tracks space weather and forecasts its changes, which can affect millions of dollars' worth of activities such as oil drilling, vehicle navigation systems and astronauts.

Half of the specialists predicted a moderately strong cycle of 140 sunspots expected to peak in October of 2011; the rest called for a moderately weak cycle of 90 sunspots peaking in August of 2012.

"We're hoping to achieve a consensus sometime in the next six to 12 months," said Douglas Biesecker, a space environment center scientist who is chairman of the forecast panel.

An average solar cycle ranges from 75 to 155 sunspots.

During an active solar period, violent eruptions occur more often on the sun, the agency said. Solar flares and vast explosions, known as coronal mass ejections, shoot highly charged matter toward Earth.

Making these predictions is important for many businesses, which have been asking for a forecast for nearly a year, Biesecker said.

Just like coastal residents want a hurricane forecast as early as possible, so do those affected by solar activity, said Joseph Kunches, chief of forecast and analysis at the center, which is part of the National Oceanic and Atmospheric Administration.

Daniel Baker, director of the Laboratory for Atmospheric and Space Physics at the University of Colorado-Boulder, noted more than $200 billion of satellites in space can be affected by changes in solar radiation as the cycle rises and falls.

In addition, Baker said, other problems include:

• Airlines flying over the poles face loss of communications that could force them to use a different, longer route at an added cost of as much as $100,000 per flight.

• Global-positioning systems are immensely important to commerce and can be disrupted by solar activity.

• Operating floating oil rigs in the ocean requires keeping them positioned within a few inches to prevent damaging drilling gear. "They have to know when GPS is going to be accurate."

• There is an increased radiation risk to humans in space.

• Currents can be induced in long electrical-transmission lines, causing blackouts.

In the past, such problems have been caused by solar superstorms, he said.

"Storms don't have to be so super any more" to cause problems, Baker said, as more and more systems become susceptible to solar effects.

W. Dean Pesnell of NASA's Solar Dynamics Observatory said the solar storms also can heat the Earth's upper atmosphere, causing it to expand. This increases drag on satellites, slowing them down. It also affects the position of the space debris encircling the planet, and it is essential to keep track of that debris for the safety of space flight.

The forecasters said the current solar cycle will probably end next March, when Solar Cycle 24 will begin. That will mean Cycle 23 lasted 12 years, slightly longer than the usual 11-year cycle.

Is there life on ... Gliese?

FORGET ABOUT life on Mars. It's all about life on Gliese 581 C.

OK, so it doesn't have a wonderful, emphatic name like the red planet that has held so many of our hopes for companionship in this dark, lonely universe. Its sun is a diminutive red dwarf, meaning that days on Gliese won't be nearly as bright as they are on our fair planet. It sure is a lot farther away -- at least 20.5 light-years outside of our solar system. According to scientists, however, it could support liquid water -- and life.

Astronomers aren't able to look yet for signs of life, but all the elements -- temperature (between 32 and 104 degrees) and distance from its star (its orbit places it within what scientists call the "habitable zone") -- are there. Computer models predict either a rocky planet, like Earth, or a water world covered with liquid oceans. Either scenario holds the possibility for extraterrestrial life. Best -- or worst? -- of all, Gliese 581 C is close enough for scientists to imagine future space missions of exploration and discovery.

Scary? For sure. Exhilarating? Definitely. For the first time, the thought of an entirely different life form appears to be within reach. But what kind of life form would exist on a planet 50 percent larger than Earth and five times more massive; a planet where one year lasts 13 Earth days? Ladies and gentlemen, we will find out far sooner than we ever imagined. Hold on tight.

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