Scientists discover massive ring around Saturn
NASA’s Spitzer Space Telescope has spotted a massive, nearly invisible ring around Saturn.
NASA's Spitzer Space Telescope has spotted a massive, nearly invisible ring around Saturn.
Its diameter is equivalent to 300 Saturns lined up side to side. And its entire volume can hold one billion Earths, NASA Jet Propulsion Laboratory said late Tuesday.
“This is one supersized ring,” said Anne Verbiscer, an astronomer at the University of Virginia in Charlottesville.
Verbiscer and two others are authors of a paper about the discovery published Wednesday in the journal Nature.
The obvious question: Why did it take scientists so long to discover something so massive?
The ring is made up of ice and dust particles that are so far apart that “if you were to stand in the ring, you wouldn’t even know it,” Verbiscer said in a statement.
Also, Saturn doesn’t receive a lot of sunlight, and the rings don’t reflect much visible light.
But the cool dust — about 80 Kelvin (minus 316 degrees Fahrenheit) — glows with thermal radiation. NASA’s Spitzer Space Telescope, used to spot the ring, picked up on the heat.
One of Saturn’s moons, Phoebe, orbits within the ring. As Phoebe collides with comets, it kicks up planetary dust. Scientists believe the ice and dust particles that make up the ring stems from those collisions.
The ring may also help explain an age-old mystery surrounding another of Saturn’s moons: Iapetus.
Astronomer Giovanni Cassini, who first spotted Iapetus in 1671, deduced the moon has a white and dark side — akin to a yin-yang symbol. But scientists did not know why.
The new ring orbits in the opposite direction to Iapetus. And, say researchers, it’s possible that the moon’s dark coloring is a result of the ring’s dust particles splattering against Iapetus like bugs on a windshield.
“Astronomers have long suspected that there is a connection between Saturn’s outer moon Phoebe and the dark material on Iapetus,” said Douglas Hamilton of the University of Maryland in College Park — one of the three authors reporting on the findings in the journal Nature.
32 planets discovered outside solar system
Thirty-two planets have been discovered outside Earth’s solar system through the use of a high-precision instrument installed at a Chilean telescope, an international team announced.
This artist's rendering shows one of the so-called exoplanets, or planets outside our solar system.
The existence of the so-called exoplanets — planets outside our solar system — was announced at the European Southern Observatory/Center for Astrophysics, University of Porto conference in Porto, Portugal, according to a statement issued by the observatory.
The announcement was made by a consortium of international researchers, headed by the Geneva Observatory, who built the High Accuracy Radial Velocity Planet Searcher, or HARPS. The device can detect slight wobbles of stars as they respond to tugs from exoplanets’ gravity. That tactic, known as the radial velocity method, “has been the most prolific method in the search for exoplanets,” according to the European Southern Observatory statement.
The instrument detects movements as small as 3.5 km/hr (2.1 mph), a slow walking pace, the observatory said.
With the discovery, the tally of new exoplanets found by HARPS is now at 75, out of about 400 known exoplanets, the organization said, “cementing HARPS’s position as the world’s foremost exoplanet hunter.” The 75 planets are in 30 planetary systems, the European Southern Observatory said.
“HARPS is a unique, extremely high precision instrument that [is] ideal for discovering alien worlds,” Stephane Udry of Geneva University, who made the announcement on behalf of the international consortium that built the instrument, said in the observatory statement. “We have now completed our initial five-year program, which has succeeded well beyond our expectations.”
HARPS has also boosted the discovery of so-called super-Earths — planets with a mass a few times that of Earth. Of the 28 super-Earths known, HARPS facilitated the discovery of 24, the European Southern Observatory statement said. Most reside in multiplanet systems, with up to five planets per system.
Although only 32 were announced Monday, the team knows of many more exoplanets, although more observation is needed before they are formally announced and papers are written about them. “We have tons of them,” Udry said.
In return for building HARPS, the consortium was provided 100 observing nights per year over five years to search for exoplanets, one of the most ambitious searches ever implemented on a global basis, the European Southern Observatory said.
“These observations have given astronomers a great insight into the diversity of planetary system and help us understand how they can form,” team member Nuno Santos said in the statement.
The HARPS findings confirm the predictions of those who study planetary formation, Udry said. “Moreover, those models are also predicting even more … Earth-type planets.”
An important find for the study of planet formation was that three exoplanets were around stars that are metal-deficient, Udry said. Metal-deficient stars are thought to be less favorable for planet formation; however, planets the size of several Jupiters were found orbiting such deficient stars, the European Southern Observatory said.
In addition, the discovery gives “a very strong push” to projects attempting to find and study such exoplanets, Udry said.
According to its Web site, the European Southern Observatory is the foremost intergovernmental astronomy organization in Europe and describes itself as the “world’s most productive astronomical observatory. ” It is supported by 14 European countries
Giant exploding star outshines previous supernovas
Scientists have just released images of the brightest stellar explosion recorded.
The supernova, known as SN 2006gy, was believed to be about 150 times as massive as the sun.
The explosion could help astronomers better understand how the first generation of stars in the universe died.
“This supernova stands out as the brightest supernova that’s ever been observed,” said Nathan Smith, astrophysicist at the University of California at Berkeley.
“The reason we’re so excited is because it was so powerful we think it may require a new type of explosion mechanism that we’ve never observed before,” said Smith at a news conference from NASA headquarters in Washington.
A supernova is a rare and often dramatic phenomenon that involves the explosion of most of the material within a star. Supernovas can be very bright for a short time and usually release huge amounts of energy.
A graduate student using a robotic telescope that was part of the Texas Supernova Search project first detected SN 2006gy on September 18, 2006.
For about 70 days it got brighter, peaking with a brightness comparable to 50 billion suns, much brighter than most other supernovas. Supernovas are usually bright for a couple of weeks at most.
Astronomers captured the star’s demise using NASA’s Chandra X-Ray Observatory, and ground- based telescopes at the Lick Observatory in California and the Keck Observatory in Hawaii. The explosion was estimated about 238 million light years away from Earth.
Scientists believe supernova SN 2006gy expelled many of its outer layers in an eruption before its violent collapse.
When it exploded, it plowed into the cooler gases that had already been expelled, creating the brightest light show ever from a supernova.
Mario Livio, astrophysicist from the Space Telescope Science Institute in Baltimore, Maryland, calls the discovery “extraordinarily intriguing” for a theorist such as himself.
“We may be learning something entirely new about how massive stars explode,” said Livio.
“We are seeing a new type of explosion that has so far only existed in theory, and we believe the first stars in the universe exploded by this mechanism. It may provide a new lesson in the evolution of stars, and a star in our own galaxy may do the same thing tomorrow,” he said.
Astronomers say the star that became SN 2006gy expelled a large amount of its mass before it exploded. A huge star in the Milky Way, Eta Carinae, has already erupted in a similar fashion. So if it explodes as a supernova, it could present the best light show seen, because it is a mere 7,500 light years away from our planet.
The orbiting Chandra X-ray Observatory, which began its mission July 23, 1999, can detect and capture images of X-ray sources that are billions of light years away. Scientists all over the world use it to get insight about high temperature events, such as black holes and collapsed stars that are millions of degrees Celsius.
Chandra is the largest satellite deployed from the space shuttle. The observatory was named after Subrahmanyan Chandrasekhar, the Indian-American astrophysicist who worked at the University of Chicago and won the 1983 Nobel prize in physics. “Chandra” means “moon” or “luminous” in the Sanskrit language.
 Scientists believe supernova SN 2006gy expelled many of its outer layers in an eruption before its violent collapse. |
Planet-hunters find bonanza of new solar systems
Planet-seekers who have spotted 28 new planets orbiting other stars in the past year say Earth’s solar system is far from unique and there could be billions of habitable planets.
The most recent planet discoveries bring the number of known exoplanets — planets outside our solar system — to 236, the researchers told a meeting of the American Astronomical Society in Honolulu Monday.
“We are beginning to see that our home is not a rarity in the universe,” said Geoffrey Marcy, a professor of astronomy at the University of California Berkeley, who led the team.
“We are easily able to detect giant planets like Jupiter and Saturn around other stars. Most orbit far from the star like our own Jupiter and Saturn orbit from the sun,” Marcy said in a telephone interview.
“It’s a common structure among planetary systems.”
New techniques allow astronomers to detect planets that are not enormous although Earth-sized objects cannot yet be seen, said the researchers.
Four of the systems also have multiple planets, like Earth’s own with its sun, eight planets (Pluto was demoted from planet status) and smaller orbiting objects.
“We are finding that most stars have not just one planet but when we find one there is a second or a third or a fourth,” Marcy said.
“The … attribute which really has us the most excited is this new planet which we found three years ago,” Marcy said. The Neptune-like planet orbiting the star Gliese 436 has intrigued scientists because it appears to be covered with water — albeit rock-hard, hot water in a most un-Earthlike chemical state because of the intense pressures on the planet.
Earlier this month, Swiss and Belgian researchers imaged the star as this planet crossed between it and the Earth. The tiny change in the star’s light gave them the planet’s diameter and density.
“From the density of two grams per cubic centimeter — twice that of water — it must be 50 percent rock and about 50 percent water, with perhaps small amounts of hydrogen and helium,” Marcy said.
“Now we are very sure it has a rocky core and this giant thick envelope of water,” he added.
“This is why we are jumping out of our clothes. It is the first time we have determined the structure of one of these extrasolar planets. It is rocky like Earth but it has a lot of water which is the essential ingredient for life.”
This is almost certainly happening over and over again, Marcy said. Scientists had theorized this for decades but now the hard evidence is starting to pour in.
“Our Milky Way galaxy has 200 billion stars. I would estimate that 10 percent of them, perhaps, have planets that are habitable,” Marcy said.
“There are hundreds of billions of galaxies, all of which are more or less like our Milky Way Galaxy, which is tens of billions of planets like our own.”
There is one unusual property to our solar system: the nearly circular orbits of the planets, which gives a consistent dose of radiation from the Sun.
Other solar systems seen so far are not usually like this. “Most of the planets are not in circular orbits around the host star but in elongated ones called elliptical orbits,” Marcy said.
“We enjoy nearly constant temperatures throughout the year,” he added. “If the Earth got too close to the sun, the Earth would heat up, the water would boil off and that would be bad.” Too far, and it would freeze.
“An elongated orbit could not sustain life,” Marcy said.
 A drawing of the Neptune-like planet orbiting star Gliese 436. |
Strong evidence of wet past on Mars
The Mars rover Spirit has uncovered the strongest evidence yet that the planet used to be wetter than previously thought, scientists reported Monday.
The robot analyzed a patch of soil in Gusev Crater and found it unusually rich in silica. The presence of water would have been necessary to produce such a large silica deposit, scientists said.
“This is a remarkable discovery,” principal investigator Steve Squyres of Cornell University said in a statement. “It makes you wonder what else is still out there.”
Spirit previously found clues of ancient water in the crater through the presence of sulfur-rich soil, water-altered minerals and explosive volcanism. But the latest find is compelling because of the high silica content, researchers said, raising the possibility that conditions may have been favorable for the emergence of primitive life.
It’s unclear how the silica deposit formed. One possibility is that the soil mixed with acid vapors in the presence of water. Others believe the deposit was created from water in a hot spring surrounding.
The durable Spirit and its twin, Opportunity, have been working on overtime since completing their primary, three-month mission in 2004.
For eight months, Opportunity has explored the rim of Victoria Crater on the opposite side of the planet. Scientists are looking for a safe opening to send the rover in.
The mission is managed at NASA’s Jet Propulsion Laboratory in Pasadena.
 A patch of Martian soil analyzed by Spirit is rich in silica — strong evidence the red planet was much wetter than it is now. |
Could black holes be portals to other universes?
The objects scientists think are black holes could instead be wormholes leading to other universes, a new study says. If so, it would help resolve a quantum conundrum known as the black hole information paradox, but critics say it would also raise new problems, such as how the wormholes would form in the first place.
A black hole is an object with such a powerful gravitational field that nothing, not even light, can escape it if it strays within a boundary known as the event horizon. Einstein’s theory of general relativity says black holes should form whenever matter is squeezed into a small enough space.
Though black holes are not seen directly, astronomers have identified many objects that appear to be black holes based on observations of how matter swirls around them.
But physicists Thibault Damour of the Institut des Hautes Etudes Scientifiques in Bures-sur-Yvette, France, and Sergey Solodukhin of International University Bremen in Germany now say that these objects could be structures called wormholes instead.
Wormholes are warps in the fabric of space-time that connect one place to another. If you imagine the universe as a two-dimensional sheet, you can picture a wormhole as a “throat” connecting our sheet to another one. In this scenario, the other sheet could be a universe of its own, with its own stars, galaxies and planets.
Damour and Solodukhin studied what such a wormhole might look like, and were surprised to discover that it would mimic a black hole so well that it would be virtually impossible to tell the difference.
Hawking radiation
Matter would swirl around a wormhole in the same way as for a black hole, since both objects distort the space around them in the same way.
One might hope to distinguish the two by something called Hawking radiation, an emission of particles and light which should only come from black holes and would have a characteristic energy spectrum. But this radiation is so weak that it would be completely swamped by other sources, such as the background glow of microwaves left over from the big bang, making it unobservable in practice.
Another difference one might hope to exploit is that unlike black holes, wormholes have no event horizon. This means that things could go in a wormhole and come back out again. In fact, theorists say one variety of wormhole wraps back onto itself, so that it leads not to another universe, but back to its own entrance.
Daring plunge
But this does not provide a foolproof test either. Depending on the detailed shape of the wormhole, it could take billions of years or more for things to pop back out after falling in. With the right shape, even the oldest wormholes in our universe would not have had time to spit anything back out yet.
It seems the only way to decide the issue for sure with astronomical black holes is to make a daring plunge inside. That would be a dangerous gamble, because if it is a black hole, the incredibly strong gravitational field inside would tear apart every atom in your body. Even if it turns out to be a wormhole, the forces inside could still be deadly.
Assuming you could survive, and the wormhole was not symmetric, you might find yourself in another universe on the other side. Without further intervention, the wormhole would tend to suck you back in and carry you back to the opening in your universe.
Yo-yo motion
“The spaceship would do this yo-yo motion,” Damour told New Scientist. “[But] if you use your fuel, then you can escape from the attracting power of the wormhole and explore” the space on the other side, he says.
But a friend in either universe might have to wait billions of years to hear back from you, since the transit time could be excruciatingly long.
Such a delay would make meaningful communication with anyone on the other side impossible. But the delay gets smaller with smaller wormholes. If a microscopic wormhole could be found or constructed, the delay across it could be as short as a few seconds, Solodukhin says, potentially making two-way communication possible.
Stephen Hsu of the University of Oregon in Eugene, US, who has studied the formation of black holes and the properties of wormholes, says he agrees that distinguishing between the two types of object with observations is practically impossible, at least with current technology.
Exotic matter
“The most important property of a black hole – that there is a ‘point of no return’ for an object falling in – is not something we can test at the moment,” he told New Scientist.
Still, he says the objects out there suspected to be black holes probably really are black holes rather than wormholes. There are plausible scenarios for forming black holes, he says, such as the collapse of a massive star, but it is not clear how you would form a wormhole.
“Wormholes that might be confused with a macroscopic black hole require some kind of exotic matter to stabilise them, and it is not known whether such exotic matter exists,” he says.
Solodukhin says that a wormhole might form in much the same way that black holes form, such as from a collapsing star. Physicists normally expect in these situations that a black hole would be produced, but Solodukhin says that quantum effects may stop the collapse just short of producing a black hole, leading to a wormhole instead.
Microscopic black holes
He says this mechanism might be inevitable in a more complete picture of physics that unites gravity and quantum mechanics – a longstanding goal of physics. If he is right, then wherever we used to expect black holes to form, wormholes would form instead.
And there might be a way to test the conjecture. Some physicists say that future particle accelerator experiments could produce microscopic black Such tiny black holes would emit measurable amounts of Hawking radiation, proving that they are black holes rather than wormholes. But if Solodukhin is right, and microscopic wormholes are formed instead, no such radiation would be expected. “In that case, you would actually see if it is a black hole or a wormhole,” he says.
An added benefit of wormholes is that they could resolve the so-called black hole information paradox. The only way anything can exit a black hole is in the form of Hawking radiation, but it is not clear how the radiation carries information about the original object that was swallowed. This scrambling effect conflicts with quantum mechanics, which forbids such erasing of information “Theoretically, wormholes are much better than black holes because all these problems with information loss don’t exist in this case,” Solodukhin says. Since wormholes have no event horizons, things are free to leave without first being converted into Hawking radiation, so there is no problem with lost information.
Scientists find Earth-like planet
European astronomers have found the most Earth-like planet outside our solar system, and here’s what it might be like to live there:
The “sun” wouldn’t burn brightly. It would hang close, large and red in the sky, glowing faintly like a charcoal ember. And it probably would never set if you lived on the sunny side of the planet.
You could have a birthday party every 13 days because that’s how fast this new planet circles its sun-like star. But watch the cake — you’d weigh a whole lot more than you do on Earth.
You might be able to keep your current wardrobe. The temperature in this alien setting will likely be a lot like Earth’s — not too hot, not too cold.
And that “just right” temperature is one key reason astronomers think this planet could conceivably house life outside our solar system. It’s also as close to Earth-sized as telescopes have ever spotted. Both elements make it the first potentially habitable planet besides Earth or Mars.
Astronomers who announced the discovery of the new planet Tuesday say this puts them closer to answering the cosmic question: Are we alone?
“It’s a significant step on the way to finding possible life in the universe,” said University of Geneva astronomer Michel Mayor, one of 11 European scientists on the team that found the new body. “It’s a nice discovery. We still have a lot of questions.”
There’s still a lot that is unknown about the new planet, which could be deemed inhospitable to life once more is learned about it. But as galaxies go, it’s practically a neighbor. At only 120 trillion miles away, the red dwarf star that this planet circles is one of the 100 closest to Earth.
The results of the discovery have not been published but have been submitted to the journal Astronomy and Astrophysics.
Alan Boss, who works at the Carnegie Institution of Washington where a U.S. team of astronomers competed in the hunt for an Earth-like planet, called it “a major milestone in this business.”
The planet was discovered by the European Southern Observatory’s telescope in La Silla, Chile, which has a special instrument that splits light to find wobbles in different wavelengths. Those wobbles can reveal the existence of other worlds.
What they revealed is a planet circling the red dwarf star, Gliese 581. Red dwarfs are low-energy, tiny stars that give off dim red light and last longer than stars like our sun. Until a few years ago, astronomers didn’t consider these stars as possible hosts of planets that might sustain life.
The discovery of the new planet, named 581 c, is sure to fuel studies of planets circling similar dim stars. About 80 percent of the stars near Earth are red dwarfs.
The new planet is about five times heavier than Earth, and gravity there would be 1.6 times as strong as Earth’s. Its discoverers aren’t certain if it is rocky like Earth or if its a frozen ice ball with liquid water on the surface. If it is rocky like Earth, which is what the prevailing theory proposes, it has a diameter about 11/2 times bigger than our planet. If it is an iceball, as Mayor suggests, it would be even bigger.
Based on theory, 581 c should have an atmosphere, but what’s in that atmosphere is still a mystery and if it’s too thick that could make the planet’s surface temperature too hot, Mayor said.
However, the research team believes the average temperature to be somewhere between 32 and 104 degrees and that set off celebrations among astronomers.
Until now, all 220 planets astronomers have found outside our solar system have had the “Goldilocks problem.” They’ve been too hot, too cold or just plain too big and gaseous, like uninhabitable Jupiter.
The new planet seems just right — or at least that’s what scientists think.
“This could be very important,” said NASA astrobiology expert Chris McKay, who was not part of the discovery team. “It doesn’t mean there is life, but it means it’s an Earth-like planet in terms of potential habitability.”
Eventually astronomers will rack up discoveries of dozens, maybe even hundreds of planets considered habitable, the astronomers said. But this one — simply called “c” by its discoverers when they talk among themselves — will go down in cosmic history as No. 1.
Besides having the right temperature, the new planet is probably full of liquid water, hypothesizes Stephane Udry, the discovery team’s lead author and another Geneva astronomer. But that is based on theory about how planets form, not on any evidence, he said.
“Liquid water is critical to life as we know it,” co-author Xavier Delfosse of Grenoble University in France, said in a statement. “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 extraterrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X.”
Other astronomers cautioned it’s too early to tell whether there is water.
“You need more work to say it’s got water or it doesn’t have water,” said retired NASA astronomer Steve Maran, press officer for the American Astronomical Society. “You wouldn’t send a crew there assuming that when you get there, they’ll have enough water to get back.”
The new planet’s star system is a mere 20.5 light years away, making Gliese 581 one of the 100 closest stars to Earth. It’s so dim, you can’t see it without a telescope, but it’s somewhere in the constellation Libra, which is low in the southeastern sky during the mid-evening in the Northern Hemisphere.
Even so, Maran noted, “We don’t know how to get to those places in a human lifetime.”
But, oh, the view, if you could. The planet is 14 times closer to the star it orbits. Udry figures the red dwarf star would hang in the sky at a size 20 times larger than our moon. And it’s likely, but still not known, that the planet doesn’t rotate, so one side would always be sunlit and the other dark.
Two teams of astronomers, one in Europe and one in the United States, have been racing to be the first to find a planet like 581 c outside the solar system.
The European team looked at 100 different stars using a tool called HARPS (High Accuracy Radial Velocity for Planetary Searcher) to find this one planet, said Xavier Bonfils of the Lisbon Observatory, one of the co-discoverers.
Much of the effort to find Earth-like planets has focused on stars like our sun with the challenge being to find a planet the right distance from the star it orbits. About 90 percent of the time, the European telescope focused its search more on sun-like stars, Udry said.
A few weeks before the European discovery earlier this month, a scientific paper in the journal Astrobiology theorized a few days that red dwarf stars were good candidates.
“Now we have the possibility to find many more,” Bonfils said.