domingo, 17 de fevereiro de 2008

Lunar eclipse visible for North America

Don't miss this total lunar eclipse, the last one for nearly 3 years.
Lunar eclipse chart
The Moon glows red among the background stars of Leo the Lion during the February 20/21 total lunar eclipse. The bright planet Saturn also lies nearby. Astronomy: Roen Kelly [View Larger Image]
February 11, 2008
The last total lunar eclipse until December 20, 2010, will thrill observers throughout North America February 20.

"This eclipse is perfect for getting the family together," Astronomy Senior Editor Michael Bakich says, "because it begins early in the evening."

On February 20, eclipse observers should plan to get out lawn chairs, binoculars, and low-power eyepieces. And, this year, better add a blanket.

A lunar eclipse occurs when the Moon, in orbit around Earth, passes into Earth's shadow. Because the Sun isn't a point of light, the shadow has two parts — the inner, darker umbra and the outer, lighter penumbra. If the whole Moon enters the umbra, the eclipse is total. If the umbra hides only part of the Moon, the eclipse is partial.

The eclipse's umbral phase begins at 8:43 P.M. EST. On the East Coast, the Moon already stands one-third of the way up in the eastern sky. For West Coast observers, the Moon rises minutes after the umbra touches its surface.

Earth's shadow takes 78 minutes to envelop the Moon. Totality (when the Moon lies completely within Earth's umbra) begins at 10:01 P.M. EST. The Moon won't disappear, however. Some sunlight passing through Earth's atmosphere falls on the lunar surface. The cleaner our atmosphere is, the lighter the eclipse will be. Dark eclipses generally occur after large volcanic eruptions.
Lunar eclipse
August's lunar eclipse, seen here, put on a nice show from western North America. This month's total eclipse, in contrast, favors the whole continent. Stephen James O'Meara [View Larger Image]
What color will the Moon turn at mideclipse? During past total eclipses, the Moon has appeared brown, orange, crimson, and brick red. Lunar eclipses exhibit a range of shades because sunlight passing through Earth's atmosphere becomes scattered and reddened. It's this dim glow that fills Earth's shadow and lights the eclipsed Moon.

During totality, the Moon's northern edge will appear darker than its southern side. This disparity occurs because the Moon's northern limb will lie closer to the center of Earth's shadow.

Totality lasts 51 minutes. During the first half, as the sky becomes progressively darker, the background stars of Leo the Lion will appear. The constellation's brightest star, Regulus, appears 3° (6 Moon-widths) above the Moon.

You also will spot Saturn easily 4° (8 Moon-widths) to the Moon's lower left. The eclipse is a great time to notice how the Moon moves through the sky. As the eclipse begins, the Moon lies 4.4° from Saturn. When the event ends, the gap measures only 3.5°.

After totality, it takes the Moon another 78 minutes to leave Earth's umbra.

Real-time space radiation forecasting in place

This advancement in predicting space weather is important to human space exploration.
Provided by the SwRI
This sketch images the inner solar system at the time the light and electrons from solar activity reach the Earth. Fast electrons and the slower ions follow magnetic lines of force. SwRI [View Larger Image]
February 15, 2008
A new method for predicting the approach and intensity of hazardous particles from extreme solar events that would threaten astronauts and technology in space is now in place. Researchers are using this initial forecasting phase to qualify the method for operational use in space exploration activities.

The forecasting development team met its early-February deadline to coincide with NASA's launch of shuttle Atlantis to transport a European laboratory to the International Space Station. Useful but not critical for shuttle operations in low-Earth orbit, testing the method in real time during realistic flight scenarios will help improve the safety of future missions to the moon and Mars.

Developed eight months ago by Dr. Arik Posner, a research scientist at Southwest Research Institute (SwRI), the methodology and hands-on approach are examples of how the latest results generated from basic heliophysics research can be transformed rapidly into operational applications.

"This system provides advance warning up to about one hour," says Posner. "Although it seems relatively short notice, the warning can be mission critical during extravehicular activities, such as on the lunar surface, but in most cases it will simply reduce astronauts' total exposure to radiation."
The one-million-degree solar corona in extreme ultraviolet light taken by the Solar and Heliospheric Observatory's Extreme ultraviolet Imaging Telescope in November 2003. Hazardous solar activity is only minutes away. Another SOHO instrument, the COSTEP, monitors space for electrons from the Sun. SwRI [View Larger Image]
"Expanding our capabilities for monitoring radiation outbursts from the Sun is one of the critical issues that we must continue to address for human space exploration. This becomes even more crucial for Exploration class missions. The transition of scientific data into an operationally useful tool is an important and invaluable approach," says Stephen Guetersloh, member of the Space Radiation Analysis Group of NASA's Johnson Space Center in Houston.

The method was developed based on observations by the Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) instrument, funded by the German Space agency DLR, on the Solar and Heliospheric Observatory. "The instrument was developed and built at the University of Kiel (Germany) in collaboration with the Alcala University (Spain). It is currently the only instrument in space which can provide the input for Posner's forecasting method," says Professor Bernd Heber from the University of Kiel.

Since SOHO launched in 1995, COSTEP has provided a wealth of data but not in real time. "We were so excited by Posner's project that we immediately teamed up and developed new software that displays the data and can give a warning 3 minutes after taking the measurements 1.5 million kilometers away," explains Oliver Rother from the University of Kiel.

The forecasting method calculates the appearance and intensity of solar ion events by measuring relativistic, near light-speed electrons. Relativistic electrons are highly abundant, easy to detect outside of the magnetosphere and detectable ahead of the more dangerous ions that follow. Extreme solar events create the relativistic electrons, which have characteristics that can be exploited to predict the time and intensity of later arriving ions, predominantly protons with energies more harmful to humans.

Energetic protons and heavier ions are among the main constituents of solar particle events, and exposure of the human body to such ionizing radiation elevates cancer risk. Heavy exposure to these particles can also result in acute radiation syndrome, with symptoms that include nausea, skin burns or disruption of central nervous system function.

"Earth's magnetic field helps prevent exposure to solar particle events," says Posner, "but as space exploration leads humans out of this protective magnetic cocoon toward the Moon and into the unprotected seas of outer space, this and other methods of space weather forecasting will become increasingly important."

Lua de Saturno tem fonte de hidrocarbonetos superior a todas as reservas de petróleo e gás da Terra

Publicada em 14/02/2008 às 11h08m
EFE ''Piscina'' deTitã, lua de Saturno - JPL/Nasa
RIO - A lua Titã, de Saturno, possui reservas de hidrocarbonetos superiores a todas as de petróleo e gás natural conhecidas na Terra, segundo observações realizadas pela sonda Cassini, revelaram o Laboratório de Propulsão a Jato (JPL) da Nasa e a Agência Espacial Européia (ESA).
Segundo cientistas do Laboratório de Física Aplicada da Universidade Johns Hopkins, esses hidrocarbonetos literalmente chovem naquele mundo e formam grandes depósitos em forma de lagos e dunas.
- Titã esta coberta por material que contém carbono. É uma gigantesca fábrica de materiais orgânicos - afirmou Ralph Lorenz, membro da equipe de cientistas que controla as operações do radar da Cassini no laboratório. - Essas enormes jazidas de carbono são uma importante janela para a geologia e a história meteorológica da lua Titã - acrescentou.
A temperatura média em Titã é de 179 graus Celsius abaixo de zero e em vez de água, sua superfície está coberta por hidrocarbonetos na forma de metano e etano.
Superfície de Titã, lua de Saturno - JPL/NasaAté agora, a Cassini realizou uma prospecção de 20% da superfície da lua Titã, e foram observados centenas de lagos e mares. Segundo a Nasa, cada uma das várias dúzias desses corpos "líquidos" contém mais hidrocarbonetos que todas as reservas de gás e petróleo conhecidas na Terra.
Além disso, suas dunas contêm um volume de materiais orgânicos centenas de vezes maior que as reservas de carvão da Terra.
- Esses cálculos se baseiam nas observações dos lagos das regiões polares setentrionais. Acreditamos que no sul podem ser similares - assinalou Lorenz.
A missão da Cassini é um projeto conjunto da Nasa, da Agência Espacial Européia e da Agência Espacial Italiana.

Sun-like star flips its magnetic field

This is the first time astronomers have observed this in a star other than our Sun.
Provided by the University of Hawaii
The magnetic field of the Sun-like star tau Bootis has flipped its north and south poles. The shortened cycle of this event may be due to interactions with its nearby massive planet. Karen Teramura/UH IfA [View Larger Image]
February 13, 2008
An international group of astronomers that includes the University of Hawaii's Evgenya Shkolnik reported today that they have discovered that the Sun-like star tau Bootis flipped its magnetic field from north to south sometime during the last year.

It has been known for many years that the Sun's magnetic field changes its direction every 11 years, but this is this is the first time that such a change has been observed in another star. The team of astronomers, who made use of Canada-France-Hawaii Telescope atop Mauna Kea, are now closely monitoring tau Bootis to see how long it will be before the magnetic field reverses again.

Magnetic field reversals on the Sun are closely linked to the varying number of sunspots seen on the Sun's surface. The last "solar minimum," the time when number of sunspots was the lowest and the magnetic flip occurred, was in 2007. The first sunspot of the new cycle appeared just last month.

The magnetic cycle of the Sun impacts the Earth's climate and is believed to have caused the little ice age in the seventeen century. The Earth's magnetic field also flips, although much less frequently and more erratically.

The international team led by Jean-Francois Donati and Claire Moutou of France caught tau Bootis in the process of flipping its magnetic field while they were mapping the magnetic fields of stars.

What makes tau Bootis even more interesting is that it harbors a giant planet orbiting very close to the surface of the star. The planet is actually so close (only one twentieth the distance between the Sun and Earth) and so massive (about 6.5 times the size of Jupiter) that it succeeded in forcing the surface of the star to co-rotate with the planet's orbital motion through tidal torques. This is the same effect that causes the moon to co-rotate around Earth so that we see only one side of the moon.

Since the astronomers managed to catch tau Bootis in this state of magnetic flipping during just 2 years of observations, it is likely that this event is much more frequent on tau Bootis than it is on the Sun. It is possible that the giant planet that has already managed to speed up the surface of tau Bootis is also spinning up the magnetic engine of its host star. The astronomers will keep their telescopes focused on tau Bootis in coming years to make sure they catch the star's next magnetic turnover. Their goal is a better understanding of how magnetic engines work in stars, including our Sun.

Slightly hotter and 20 percent more massive than the Sun, tau Bootis is fairly bright and visible with the naked eye and located only 51 light-years away from us. It is currently rises about midnight and is visible for most of the night near the bright star Arcturus in the constellation Bootis in the northeast part of the sky.

Telescopes Spot One of Earliest Galaxies

February 12, 2008
Associated Press/AP Online

By SETH BORENSTEIN WASHINGTON - Astronomers took pictures of a far-off lumpy galaxy just forming 13 billion years ago, putting it among the earliest and most distant cosmic objects ever photographed.

Though the black-and-white images are fuzzy, they are the most detailed and best confirmed look back in both time and distance that humans have seen, said Johns Hopkins University astronomy professor Holland Ford. He was part of a team of scientists taking the pictures with NASA's space telescopes, Hubble and Spitzer.

The galaxy, called A1689-zD1, is from when the universe was about 700 million years old, not long after the formation of the first galaxies.

And it's different from galaxies like our Milky Way, Ford said.

"It is much smaller. It is lumpy. It has two centers instead of one and it is undergoing extreme star formation," he said. "It is basically the building blocks for what will be a galaxy like our own in the future."

To see that far away, astronomers needed a little luck and help from the cosmos. A cluster of much closer galaxies act as a natural zoom lens for Earth's telescopes. Strong gravitational forces bend light around that cluster of galaxies, magnifying the light from directly behind it.

In this case, the infant galaxy appeared at least 10 times brighter than it would have without the natural help, Ford said. Other places behind the cluster appear hundreds of times sharper. This natural lens has to be lined up perfectly in order to see what's behind it, he said.

When Earth gets stronger telescopes in the future, including a new space telescope to be launched in 2013, this young galaxy would be a good place to look, astronomers said.




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Light Echoes Refine Cepheid Distance

RS Puppis and surrounding nebula
The bright Cepheid variable star RS Puppis (hidden behind a black occulting bar to block its glare) illuminates a dim reflection nebula around it. By seeing how long each brightness pulse from the star took to reach various blobs in the nebula, astronomers could find the true distances from the star to the blobs. That, combined with the angular star-to-blob separations on the sky, tells the distance from Earth — without relying on any other data or assumptions about the star itself.
P. Kervella and others
For nearly a century now, astronomers have used Cepheid variable stars as "standard candles" whose apparent brightnesses tell how far away they are. Starting in 1912 Cepheids provided the first good distances to nearby galaxies. One of the reasons for building the Hubble Space Telescope was to measure Cepheids in galaxies farther out than could be done through Earth's fuzzy atmosphere.

Indeed, "Hubble" was something of a double-entendre. The name honored the late Edwin Hubble, but the telescope was also intended to pin down the Hubble constant — the expansion rate of the universe — by comparing the redshifts of key galaxies to their distances found using Cepheid variables.

However, this only works if you know the distances to local Cepheids in our own galaxy well enough to calibrate the Cepheid distance scale as a whole. They're rather unusual super giant stars, so none of them lie close enough to the solar system for really accurate parallax measurements of their distances. Accordingly, astronomers have been expending great efforts to deduce local Cepheids' distances accurately in any way they can.

The best such measurements recently attained an accuracy of just a few percent. Now a group of astronomers has broken that record — by using a unique method to get a range on the bright Cepheid RS Puppis good to about 1.4 percent.

They did it by measuring "light echoes" of the star's pulsations on a surrounding reflection nebula, combined with the star's accurately known pulsation period, the speed of light, and some simple geometry.

RS Puppis varies in brightness (from magnitude 6.5 to 7.6) every 41.4 days. It is 10 times more massive than the Sun, 200 times larger, and on average 15,000 times more luminous. Pierre Kervella and his colleagues used the European Southern Observatory's New Technology Telescope at La Silla, Chile, to record the faint reflections of these light pulses moving across the nebula. The speed at which they appeared to move, combined with the known speed of light, gave the distance to the nebula and star: 6,500 light years plus or minus 90.

RS Pup is the only Cepheid embedded in a large nebula. "Light that travels from the star to a dust grain to the telescope arrives a bit later than light that comes directly from the star to the telescope," explains Kervella. "As a consequence, if we measure the brightness of a particular, isolated dust blob in the nebula, we obtain a brightness curve that has the same shape as the variation of the Cepheid, but shifted in time." The delay is called a "light echo," by analogy with a sound echo off, say, a canyon wall.

"Knowing the distance to a Cepheid star with such an accuracy proves crucial to the calibration of the period-luminosity relation of this class of stars," says Kervella.

RS Pup is especially important because it's one of the longest-period nearby Cepheids, and few of these have been well measured. The new result should help firm up the entire cosmic distance scale.

Gas from Saturn's largest moon

Titan's surface organics surpass oil reserves on Earth.
Provided by the Jet Propulsion Laboratory
An artist's imagination of hydrocarbon pools, icy and rocky terrain on the surface of Saturn's largest moon. Steven Hobbs (Brisbane, Queensland, Australia) [View Larger Image]
February 14, 2008
Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new data from NASA's Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes.

"Titan is just covered in carbon-bearing material, it's a giant factory of organic chemicals," says Ralph Lorenz, Cassini radar team member from the Johns Hopkins University Applied Physics Laboratory. "This vast carbon inventory is an important window into the geology and climate history of Titan."

At a balmy -290° F (-179° C), Titan is a far cry from Earth. Instead of water, liquid hydrocarbons in the form of methane and ethane are present on the moon's surface, and tholins probably make up its dunes. The term "tholins"was coined by Carl Sagan in 1979 to describe the complex organic molecules at the heart of prebiotic chemistry.

Cassini has mapped about 20 percent of Titan's surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.

Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300 times the amount of energy the entire United States uses annually for residential heating, cooling and lighting. Dozens of Titan's lakes individually have the equivalent of at least this much energy in the form of methane and ethane.

"This global estimate is based mostly on views of the lakes in the northern polar regions. We have assumed the south might be similar, but we really don't yet know how much liquid is there," says Lorenz. Cassini's radar has observed the south polar region only once, and only two small lakes were visible. Future observations of that area are planned during Cassini's proposed extended mission.

Scientists estimated Titan's lake depth by making some general assumptions based on lakes on Earth. They took the average area and depth of lakes on Earth, taking into account the nearby surroundings, like mountains. On Earth, the lake depth is often 10 times less than the height of nearby terrain.

"We also know that some lakes are more than 10 meters or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't," says Lorenz.

The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space. If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan's past.

"We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe," adds Lorenz.

Cassini's next radar flyby of Titan is on February 22, when the radar instrument will observe the Huygens probe landing site.

Isolated galaxy or corporate merger?

Hubble spies NGC 1132.
Provided by the Space Telescope Science Institute
This Hubble image shows elliptical galaxy NGC 1132. NASA/ESA/Hubble Heritage (STScI/AURA) [View Larger Image]
February 7, 2008
The elliptical galaxy NGC 1132 reveals the final result of what may have been a group of galaxies that merged together in the recent past. Another possibility is that the galaxy formed in isolation as a lone wolf in a universe ablaze with galaxy groups and clusters.

NGC 1132 is dubbed a "fossil group" because it contains enormous concentrations of dark matter, comparable to the dark matter found in an entire group of galaxies. NGC 1132 also has a strong X-ray glow from an abundant amount of hot gas that is normally only found in galaxy groups.

In visible light, however, it appears as a single, isolated, large elliptical galaxy. The origin of fossil-group systems remains a puzzle. They may be the end-products of complete merging of galaxies within once-normal groups. Or, they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.

Elliptical galaxies are smooth and featureless. Containing hundreds of millions to trillions of stars, they range from nearly spherical to very elongated shapes. Their overall yellowish color comes from the aging stars. Because ellipticals do not contain much cool gas, they no longer can make new stars.

This image of NGC 1132 was taken with Hubble's Advanced Camera for Surveys. Data obtained in 2005 and 2006 through green and near-infrared filters were used in the composite. In this Hubble image, NGC 1132 is seen among a number of smaller dwarf galaxies of similar color. In the background, there is a stunning tapestry of numerous galaxies that are much larger but much farther away.

NGC 1132 is located approximately 318 million light-years away in the constellation Eridanus, the River.

A Triple Threat

Two days ago the IAU's quaintly named Central Bureau for Astronomical Telegrams announced that astronomers have discovered a triple asteroid passing in Earth's vicinity.

This isn't the first rock trio — out in the main asteroid belt, 87 Sylvia has two small moons (Romulus and Remus) and so does 45 Eugenia (Petit-Prince and another designated S/2004 (45) 1). Multiple asteroids are no longer big news. Based on the terrestrial cratering record, about one in six impacts with Earth involves a double object.

Triple asteroid
A visualization of the radar echoes acquired February 13, 2008, from asteroid 2001 SN263. Radar illumination is from the top. Echoes from the two satellites appear thinner because they are rotating slowly and therefore don't produce as much Doppler shifting (horizontal axis) as the main mass.
National Astronomy and Ionosphere Center
But this one is a rather different animal. First, it's in an Amor-type orbit, meaning that it comes to within 96.4 million miles of the Sun but doesn't quite cross the orbit of Earth. Second, its three components are rather similar in size. The main body is roughly 1½ miles (2 km) across, whereas the other two are closer to 1,000 feet (300 meters).

The threesome came to light because a team headed by Cornell astronomer Mike Nolan used the Arecibo radio telescope in Puerto Rico to bounce radar pulses off a small asteroid passing within about 7 million miles of Earth. When three echoes came back on Tuesday, Nolan knew they'd found something special.

First seen in September 2001, this object has two official designations: 2001 SN263 (its ID when discovered) and 153591 (assigned once its orbit was known well). But this alphanumeric jumble gets worse: according to IAU convention, for now the two little satellites will be known as S/2008 (153591) 1 and S/2008 (153591) 2. Can't we just call them Moe, Larry, and Curly and be done with it?

Nolan notes in a press release that not much is known about the trio. But more observations in the coming days might determine whether the moonlets are orbiting in the same plane, the masses of all three objects, and whether the trio formed in the asteroid belt or due to a close brush with Earth.

Arecibo radio telescope
The 305-meter (1,000-foot) radio telescope near Arecibo, Puerto Rico, has been used for radar probing of solar-system objects since the early 1960s. The facility underwent a $27 million upgrade in the mid-1990s.
David Parker (Science Photo Library); courtesy NAIC/Arecibo Observatory
Because it's in a near-Earth orbit, breakup specialist Derek Richardson (University of Maryland) thinks 2001 SN263 could have been ripped apart by Earth's gravity in the not-too-distant past. "You need to get within 4 Earth radii or so [about 15,000 miles or 25,000 km] for anything interesting to happen."

He doesn't think the breakup occurred in the asteroid belt, citing the unlikelihood of the threesome staying intact for the millions of years it would have taken to migrate inward. Nor does he think subtle solar forces caused it to spin so rapidly that it flew apart.

Incidentally, Arecibo's unique radar observations may come to an abrupt end in 2011 (along with its other valuable contributions). That's because a 2005 review by the National Science Foundation decided that funds for the facility could be better spent elsewhere. But the facitity's astronomers aren't going down without a fight.

Researchers Find a Supernova, Before it Exploded

Written by Fraser Cain
SN 2007on. Image credit: Chandra
The problem with supernovae is that you never know where they're going to happen. Your only clue is the bright flash in the sky, and then it's too late. But a team of European researchers think they were lucky enough to have spotted the precursor to supernova.

In an article in the February 14th issue of the journal Nature, a team of European researchers describe how they were trying to find evidence of a binary system after one of the objects detonated as a supernova. In looking back through archived images captured by NASA's Chandra X-Ray Observatory, they were lucky enough to find one image that actually contained the system.
The supernova, known as SN 2007on exploded as a Type Ia. This is the situation where a white dwarf is in orbit around another star. It's possible that the white dwarf feeds off material ejected from the other star until it hits a critical amount of mass - approximately 1.4 times the mass of our Sun. Or maybe it's actually a collision between a white dwarf and another star, or between two white dwarfs.
Whatever the condition, the result is always the same. The white dwarf detonates suddenly with a very specific amount of energy and characteristic light curve. Astronomers use these explosions to measure distance in the Universe, since they're always exploding with the same amount of energy.
To really figure out what's going on, astronomers need more examples of these precursors. They need to be able to study a potential Type Ia supernova before it actually explodes.
So, the researchers finally have a target they can study. In the case of SN 2007on, the data gathered by the Chandra X-Ray Telescope strengthens the "mass stealing" theory. X-rays streaming from the system show the kind of fusion you would expect from a white dwarf consuming material from a neighbour.
This isn't a slam dunk, though. A higher-quality optical image shows the binary system to be in a slightly different position from where the supernova detonated. So maybe this system isn't the precursor after all.
But followup observations from Chandra show that the X-ray source is gone. Whatever was at that location isn't there any more. Perhaps it did indeed vaporize in a supernova explosion.

Bookmark in Connotea UK space strategy draws fire - February 14, 2008

The UK today launched its new space strategy (press release). Already it's being criticised by people who want more commitment to manned exploration and others who want less. The latter want space exploration money spent on propping up the UK's threatened physics and astronomy research communities instead.
Instead of going to the Moon, the strategy outlines plans to set up an international facility focusing on satellites for monitoring climate change and commercial applications as well as working on robotic space exploration. Not that the government has ruled out putting humans into space. Instead they have produced a report on their strategy which announces a review of human spaceflight.
You can listen to science minister Ian Pearson discuss manned spaceflight on Radio 4's Today Programme. "What we've said is we will have a review that will look at all the options," he says.
You might think that you'd want to review the possibility of getting involved in human spaceflight before you produce a space strategy, but nevermind.

In an opinion piece in the Times Martin Rees, the UK's Astronomer Royal and president of the Royal Society, knows what he thinks of manned missions:
The burgeoning scientific, environmental, commercial and military applications of space have not needed manned spaceflight, but have benefited from the technical advances - unimagined in the 1970s - that have given us mobile phones and the internet.

He also thinks that getting involved in NASA and the International Space Station was a bit of a mistake:

It is claimed by Nasa that tens of billions more dollars must be spent to finish the space station, in order to keep faith with the foreign partners who have built parts of it. However, whatever their public rhetoric, most European scientists regret having got involved; they could all have been contentedly paid off far more cheaply than it will cost the Americans to finish the space station.

It seems you really can't please people when it comes to space. The Guardian's coverage of the new strategy is headlined "UK carves out its place in space, but hopes for Britons on moon dashed". Its coverage continues by quoting people who want Britons in space.
Some are linking this story to the recent cutbacks in UK physics and astronomy research (see Nature here and here; subscription required). They have got something of a point: having well funded space exploration and no astronomers seems rather like buying a very expensive car and being too cheap to buy a map so you can drive it somewhere interesting.
Ever-flippant news source The Register notes:

Blighty's physics and astronomy boffins are facing severe job losses as a result, and are already up in arms. If even more of them were sacrificed to pay for a small number of space aces - some of whom at least would presumably not be scientists at all - there would be even more trouble.

Over in the comments section of the BBC's coverage one reader takes raises the fact that the UK recently slashed the amount of research it will fund in physics. "I note that this is about investing in sending up celebrities in rockets, it explains why Science and Physics research has been cut - in order to fund some more Nu labour spin. Pathetic," says Jeremy Slawson.
In the comments of the Time's coverage 'caffeineman' opines:

What will happen, indeed is already happening, is that other areas of research will be cut to bolster the funding of the manned space program. Areas of particle physics in which UK leads the world are being cut at the time of writing, by the Science and Technology Facilities Council. Money from exceptionally good science programmes will be diverted into an incredibly expensive and scientifically pointless white elephant. What a waste of the taxpayers' money !

Image color image of the sun, Earth and Venus was taken by the Voyager

Titan has "Hundreds of Times More" Liquid Hydrocarbons Than Earth

Written by Ian O'Neill
Titans landscape as seen by the Huygens probe decent through Saturns largest moons atmosphere (credit: ESA, NASA, JPL, UA, Rene Pascal)
According to new Cassini data, Saturns largest moon, Titan, has "hundreds" times more liquid hydrocarbons than all the liquid fossil fuel deposits on Earth. This is impressive as Titan's 5150 km diameter is only about 50% larger than Earth's Moon and only a little larger than the planet Mercury. Titan's hydrocarbons cycle into the atmosphere, fall as rain and collect in lakes creating massive lakes and dunes.

Titan is a planet-sized hydrocarbon factory. Instead of water, vast quantities of organic chemicals rain down on the moon's surface, pooling in huge reservoirs of liquid methane and ethane. Solid carbon-based molecules are also present in the dune region around the equator, dwarfing Earth's total coal supplies. Carl Sagan coined the term "tholins" to describe prebiotic chemicals, and the dunes of Titan are expected to be teeming with them. Tholins are essential for the beginning of carbon-based organisms, so these new observations by Cassini will stir massive amounts of excitement for planetary physicists and biologists alike.
The cold -179°C (-290°F) landscape of Titan is currently being mapped by the Cassini probe as it orbits the ringed gas giant, Saturn. Some 20% of the moons surface has been catalogued and so far several hundred hydrocarbon seas and lakes have been discovered. These lakes, individually, have enough methane/ethane energy to fuel the whole of the US for 300 years.
These new findings have been published in the January 29th issue of the Geophysical Research Letters by Ralph Lorenz from the Cassini radar team (Johns Hopkins University Applied Physics Laboratory, USA). Lorenz said on reviewing the Cassini data that, "we know that some lakes are more than 10 m or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't." He also steps into the life-beyond-Earth debate by pointing out: "We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe."
The ESA Huygens probe separated from Cassini and dropped slowly through the Titan atmosphere in January 2005 analyzing the atmospheric composition and taking some breathtaking images of the surrounding landscape. To complement the huge amount of data assembled from Huygens decent, Cassini will flyby the moon again on February 22nd to take radar data of the Huygens landing site.

Could the First Stars Have Been Powered by Dark Matter?

Written by Ian O'Neill
Time line of the Universe, early stars may have been powered by dark matter, and not fusion reactions (Credit: NASA/WMAP Science Team)
Early stars that began to form about 200 million years after the Big Bang were strange creatures. From observation, the earliest stars (formed from coalescing primordial gas clouds) were not dense enough to support fusion reactions in their cores. Something within the young suns was counteracting the collapsing gas clouds, preventing the core reactions from taking place. Yet, they still produced light, even in absence of nuclear processes. Could dark matter have had a part to play, fueling the stellar bodies and sparking early stars to life?

New research indicates that the energy generated by annihilating dark matter in the early universe may have powered the first stars. How? Well, the violent early universe will have had high concentrations of dark matter. Dark matter has the ability to annihilate when it comes into contact with other dark matter matter, it does not require anti-dark matter to annihilate. When "normal" matter collides with its anti-component (i.e. electron colliding with positron), annihilation occurs. Annihilation is a term often used to describe the energetic destruction of something. While this is true, the annihilation products from dark matter include huge amounts of energy to create neutrinos and "ordinary matter" such as protons, electrons and positrons. Dark matter annihilation energy therefore has the ability to condense and create the matter we see in the Universe today.
"Dark matter particles are their own anti. When they meet, one-third of the energy goes into neutrinos, which escape, one-third goes into photons and the last third goes into electrons and positrons." - Katherine Freese, Theoretical Physicist, University of Michigan.
Katherine Freese (University of Michigan), Douglas Spolyar (University of California, Santa Cruz) and Paolo Gondolo (University of Utah in Salt Lake City) believe the strange physics of the early "dark stars" may be attributed to dark matter. For a star to form from stellar gas cloud to a viable, burning star, it must cool first. This cooling allows the star to collapse so the gas is dense enough to kick-start nuclear reactions in the core. However, early stars appear to have some form of energy acting against the cooling and collapse of early stars, fusion shouldn't be possible, and yet the stars still shine.
The group believe that early stars may have passed through two stages of development. As the gas clouds collapse, the stars go through a "dark matter phase", generating energy and producing normal matter. As the phase progresses, dark matter will slowly be used up and converted into matter. As the star becomes sufficiently dense with matter, fusion processes take over, starting the "fusion phase". Fusion in turn generates heavier elements (such as metals, oxygen, carbon and nitrogen) during the lifetime of the star. When the early stars' fuel is used up, it will go supernova, exploding and distributing these heavy elements throughout space to form other stars. The "dark matter phase" appears only to have existed in the very first stars (a.k.a. "population three stars"); later stars are supported by fusion processes only.
However, this exciting new theory will have to wait until the James Webb Telescope goes into operation in 2013 before population three stars can be observed with any great accuracy. Light may then be shone on the processes powering the first "dark stars" of our early Universe.

Synthetic Black Hole Event Horizon Created in UK Laboratory

Written by Ian O'Neill
An artists impression of a black hole
Researchers at St. Andrews University, Scotland, claim to have found a way to simulate an event horizon of a black hole - not through a new cosmic observation technique, and not by a high powered supercomputer… but in the laboratory. Using lasers, a length of optical fiber and depending on some bizarre quantum mechanics, a "singularity" may be created to alter a laser's wavelength, synthesizing the effects of an event horizon. If this experiment can produce an event horizon, the theoretical phenomenon of Hawking Radiation may be tested, perhaps giving Stephen Hawking the best chance yet of winning the Nobel Prize.

So how do you create a black hole? In the cosmos, black holes are created by the collapse of massive stars. The mass of the star collapses down to a single point (after running out of fuel and undergoing a supernova) due to the massive gravitational forces acting on the body. Should the star exceed a certain mass "limit" (i.e. the Chandrasekhar limit - a maximum at which the mass of a star cannot support its structure against gravity), it will collapse into a discrete point (a singularity). Space-time will be so warped that all local energy (matter and radiation) will fall into the singularity. The distance from the singularity at which even light cannot escape the gravitational pull is known as the event horizon. High energy particle collisions by cosmic rays impacting the upper atmosphere might produce micro-black holes (MBHs). The Large Hadron Collider (at CERN, near Geneva, Switzerland) may also be capable of producing collisions energetic enough to create MBHs. Interestingly, if the LHC can produce MBHs, Stephen Hawking's theory of "Hawking Radiation" may be proven should the MBHs created evaporate almost instantly.
Hawking predicts that black holes emit radiation. This theory is paradoxical, as no radiation can escape the event horizon of a black hole. However, Hawking theorizes that due to a quirk in quantum dynamics, black holes can produce radiation.
The principal of Hawking Radiation (source:
Put very simply, the Universe allows particles to be created within a vacuum, "borrowing" energy from their surroundings. To conserve the energy balance, the particle and its anti-particle can only live for a short time, returning the borrowed energy very quickly by annihilating with each other. So long as they pop in and out of existence within a quantum time limit, they are considered to be "virtual particles". Creation to annihilation has net zero energy.
However, the situation changes if this particle pair is generated at or near an event horizon of a black hole. If one of the virtual pair falls into the black hole, and its partner is ejected away from the event horizon, they cannot annihilate. Both virtual particles will become "real", allowing the escaping particle to carry energy and mass away from the black hole (the trapped particle can be considered to have negative mass, thus reducing the mass of the black hole). This is how Hawking radiation predicts "evaporating" black holes, as mass is lost to this quantum quirk at the event horizon. Hawking predicts that black holes will gradually evaporate and disappear, plus this effect will be most prominent for small black holes and MBHs.
Prof Ulf Leonhardt is hoping to create the conditions of a black hole event horizon by using laser pulses, possibly creating the first direct experiment to test Hawking radiation. Leonhardt is an expert in "quantum catastrophes", the point at which wave physics breaks down, creating a singularity. In the recent "Cosmology Meets Condensed Matter" meeting in London, Leonhardt's team announced their method to simulate one of the key components of the event horizon environment.
Light travels through materials at different velocities, depending on their wave properties. The St. Andrews group use two laser beams, one slow, one fast. First, a slow propagating pulse is fired down the optical fiber, followed by a faster pulse. The faster pulse should "catch up" with the slower pulse. However, as the slow pulse passes through the medium, it alters the optical properties of the fiber, causing the fast pulse to slow in its wake. This is what happens to light as it tries to escape from the event horizon - it is slowed down so much that it becomes "trapped".
"We show by theoretical calculations that such a system is capable of probing the quantum effects of horizons, in particular Hawking radiation." - From a forthcoming paper by the St. Andrews group.
The effects that two laser pulses have on eachother to mimic the physics within an event horizon sounds strange, but this new study may help us understand if MBHs are being generated in the LHCs and may push Stephen Hawking a little closer toward a deserved Nobel Prize.

Quinze anos em órbita


Agência FAPESP – O primeiro satélite brasileiro completou 15 anos de operação no sábado (9/2). Apesar de tanto tempo em órbita, o SCD-1 (Satélite de Coleta de Dados) se mantém plenamente operacional, retransmitindo informações para a previsão do tempo e monitoramento das bacias hidrográficas, entre outras aplicações.

Projetado, construído e operado pelo Instituto Nacional de Pesquisas Espaciais (Inpe), o satélite foi lançado pelo foguete norte-americano Pegasus, em 1993, com a expectativa de apenas um ano de vida útil.

"A longevidade do SCD-1 – e também do SCD-2, que completou dez anos em outubro – é resultado de alta competência tecnológica, do rigor empregado no projeto e processo de qualificação, tanto no nível de componentes como de subsistemas, e do delicado processo de integração e testes", disse Valcir Orlando, do Centro de Rastreio e Controle de Satélites do Inpe.

Em seu 15º aniversário, o satélite completará 79.152 voltas em torno da Terra, tendo percorrido mais de 3,5 bilhões de quilômetros, equivalente a 4.665 viagens de ida e volta à Lua.

Viajando a uma velocidade orbital da ordem de 27 mil quilômetros por hora, o SCD-1 tem órbita circular de aproximadamente 750 quilômetros de altitude, com 25 graus de inclinação em relação ao plano do Equador. Nesses 15 anos, os técnicos do Inpe executaram 36 manobras de reorientação de seu eixo de rotação, sendo que o satélite recebeu um total de aproximadamente 183.140 telecomandos.

O lançamento do SCD-1 foi o início da operação do Sistema de Coleta de Dados Brasileiro, que consiste de uma rede de satélites em órbita baixa que retransmitem a um centro de missão os dados ambientais recebidos de um grande número de plataformas de coleta de dados espalhadas pelo território nacional.

Atualmente, o Sistema de Coleta de Dados é composto pelos satélites SCD-1, SCD-2, CBERS-2 e CBERS-2B, sendo que suas informações são distribuídas a diversas instituições no Brasil e no exterior.

O satélite capta e retransmite os sinais das plataformas para a estação de recepção e processamento do Inpe em Cuiabá (MT) e depois os dados são transmitidos para a unidade de Cachoeira Paulista (SP), onde ficam à disposição das empresas e instituições usuárias do sistema.

Segundo o Inpe, os dados coletados pelo satélite SCD-1 são utilizados em diversas aplicações, como previsão de tempo, estudos sobre correntes oceânicas, marés, química da atmosfera, planejamento agrícola, entre outras. Uma aplicação de grande relevância é o monitoramento das bacias hidrográficas, que fornecem dados fluviométricos e pluviométricos.

Mais informações:

Estudo indica que água marciana era salgada demais para abrigar vida

CLAUDIO ANGELO-Enviado especial da Folha de S.Paulo a Boston
Que Marte teve muita água em algum momento do seu passado é algo de que poucos cientistas duvidam hoje. Mas quem acha que isso bastou para a vida surgir no planeta vermelho provavelmente vai se frustrar: novas evidências sugerem que os mares marcianos eram tão salgados que poucos organismos poderiam ter sobrevivido àquele ambiente.
As conclusões foram apresentadas ontem pelo paleontólogo Andrew Knoll, da Universidade Harvard (EUA). Especialista na origem da vida na Terra, Knoll tem analisado os dados enviados pelos jipes-robôs Spirit e Opportunity, da Nasa, que passeiam por Marte há quatro anos.
Em uma conferência durante a reunião anual da AAAS (Associação Americana para o Avanço da Ciência), Knoll afirmou que, na época em que o vizinho da Terra tinha seus mares, há cerca de 3 bilhões de anos, as condições para a proliferação de bactérias "não eram adequadas", diferentemente do que muita gente crê. Isso porque, além de salgadas, as águas também eram ácidas. O pesquisador baseou suas conclusões, que devem ser publicadas em breve em um artigo científico, nos dados enviados pelo Opportunity de uma região conhecida como Meridiani Planum.
O local possui sedimentos que foram depositados pelas águas cerca de 3 bilhões de anos atrás. A análise química desses sedimentos já havia dado a outros cientistas a primeira pista de que o local era um habitat ruim para microrganismos: alguns dos minerais presentes nela só se formam em ambientes extremamente ácidos.
Knoll levou a análise química um passo além, no que ele chama de "pausa para reflexão" sobre os dados dos robôs. "Tem acontecido tanta coisa desde que eles chegaram lá que não houve tempo para parar e refletir sobre esses dados."
Grosso modo, o que o cientista fez foi o inverso do que qualquer pessoa pode fazer em casa com um copo d'água e sal de cozinha. "Quando você coloca sal de cozinha em uma solução, você pode acrescentá-lo até o ponto de saturação. Depois disso ele começa a precipitar [depositar-se no fundo]", afirmou Knoll. De forma inversa, olhando para a concentração de sal nos sedimentos, é possível ter uma idéia de quanto dele havia dissolvido na água, como se isso fosse uma espécie de "assinatura química" do líquido.
Em Meridiani, o principal sal presente era o sulfato de magnésio, a julgar pelos dados enviados pelo robô explorador. A concentração a partir da qual ele se precipita é maior do que a que existe na água do mar, na Terra. "Talvez haja umas duas dezenas de micróbios na Terra que podem tolerar essa concentração", disse Knoll. Aliás, disse, "toda a indústria de preservação de alimentos se baseia no fato de que há poucas bactérias resistentes à salinidade."
Em outra região estudada, o principal sal presente é o sal de cozinha (cloreto de sódio), mas em concentrações muito superiores à da água do mar. Uma bela salmoura para conservar picles, mas um péssimo lugar para surgirem células vivas.
Frio e seco
Outro problema para o surgimento da vida é o tempo durante o qual houve água líquida na superfície de Marte. O surgimento e a permanência dos oceanos da Terra foram fundamentais para a vida. Marte pode até ter tido muita água, mas um número cada vez maior de dados tem apontado para oceanos um tanto quanto efêmeros.
"Acho que há um sentimento crescente na comunidade científica de que Marte tem sido um lugar frio e seco há muito tempo", afirmou Knoll.
"Ter água por duas semanas em um intervalo de um milhão de anos não adianta."

China perdeu 10% de suas florestas devido a onda de frio

Publicada em 09/02/2008 às 15h28m
O Globo OnlineEFE A neve cobriu áreas extensas no sodoeste da China - Reuters
PEQUIM - Mais de 17,3 milhões de hectares de floresta na China, cerca de 10% do total no país, foram destruídos pela onda de frio e nevascas que levou o caos ao centro e sul do país.
Junto com os números, divulgados neste sábado pela agência de notícias estatal "Xinhua", a Administração Estatal de Florestas advertiu que algumas florestas pouco acostumadas a baixas temperaturas, como as de bambu, ficaram "gravemente destroçadas".
Dezoito divisões administrativas do país (de um total de 30) sofreram perdas nas florestas, e nas mais afetadas até 90% das matas ficaram "arruinadas", segundo as informações. Embora a Administração não tenha apresentado números sobre perdas econômicas, relatórios anteriores da instituição estimavam os danos, no final de janeiro, em US$ 2,5 bilhões apenas no setor florestal.
Veja aqui imagens do caos e dos estragos provocados pelas nevascas Para a recuperação das florestas perdidos, a Administração iniciará na primavera uma campanha de plantação, mas já advertiu aos governos locais que controlem a poda indiscriminada de árvores nas próximas semanas. As autoridades florestais temem que, com o caos criado pelas nevascas, moradores tentem se aproveitar para desmatar as florestas para vender madeira, alegando que as árvores caíram devido ao mau tempo.
Por outro lado, a Administração também advertiu que as árvores que caíram devem ser retiradas imediatamente, já que o excesso de madeira seca nas zonas florestais poderia aumentar o risco de incêndios no verão.
A onda de frio também pode ter causado a morte de diversas aves migratórias no sul do país, algumas delas pertencentes a espécies em risco de extinção. As nevascas mataram mais de 14 milhões de aves de granja e de cerca de 1,5 milhão de porcos, vacas e cordeiros.
Mais de 60 pessoas morreram desde o início das nevascas. Os estragos provocados pelo clima prejudicaram a comemoração do Ano Novo na China, que segue o calendário lunar. As celebrações para a chegada do Ano do Rato começaram com parte do país às escuras.
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Astrônomos amadores ajudam a descobrir novo sistema solar

da France Presse, em Chicago
Cientistas descobriram, com a contribuição de astrônomos amadores, um sistema solar distante mas muito similar ao nosso, de acordo com um estudo publicado nesta quinta-feira (14) pela revista "Science".
As primeiras observações levaram à descoberta de dois planetas em órbita em torno de uma estrela distante cerca de 5.000 anos-luz e que parecem ser versões menores de nossos planetas Júpiter e Saturno.

Concepção artística do sistema solar descoberto; no centro, planeta similar a Júpiter e, ao fundo, formação parecida com Saturno.

Apenas 25 sistemas solares de vários planetas foram registrados até hoje, mas é a primeira vez que é descoberto um parecido com o nosso, ressalta o principal autor do estudo, Scott Gaudi, da Universidade do Estado de Ohio (norte dos Estados Unidos).
"É como uma versão em escala reduzida de nosso sistema solar", explica. Segundo o pesquisador, estes planetas estão em órbita em torno de uma estrela "menor, mais fria e menos brilhante que o Sol". Eles estão mais próximos desta estrela do que Júpiter e Saturno do Sol e são um pouco mais frios, acrescentou.
"Nada sabemos sobre eles, a não ser a sua massa", explicou. Um deles representa cerca de 70% a massa de Júpiter, e o outro, 90% a de Saturno.
A existência destes dois planetas foi revelada quando sua estrela passou diante da órbita de uma estrela mais distante. Isso aumentou conseqüentemente a luminosidade da estrela mais remota, refratada pelos campos gravitacionais dos dois planetas.
Gaudi e sua equipe determinaram a massa desses dois planetas com base nos cálculos sobre a mudança de luminosidade, um fenômeno chamado microlente gravitacional.
Mas o fenômeno pôde apenas ser observado em um período de duas semanas, entre o final de março e início de abril de 2006. Scott Gaudi e seus companheiros pediram ajuda a todos que pudessem coletar observações.
Eles foram auxiliados pela cooperação de astrônomos amadores do hemisfério sul e de profissionais de 11 observatórios de todo o mundo: Chile, Tasmânia, Nova Zelândia, Ilhas Canárias, Israel e Estados Unidos.
"Foi mais um esforço de coordenação do que de tecnologia", segundo Scott Gaudi. Mesmo que muitos astrônomos amadores utilizem os pequenos telescópios "que têm em suas salas, a localização é mais importante para nós" que o tamanho, explicou. "Para ver o centro da galáxia, é preciso estar no hemisfério sul", diz.
Jenny McCormick de Auckland, Nova Zelândia, ficou feliz por ter contribuído. "Como um astrônomo amador que atua em seu jardim no fim do mundo com um pequeno telescópio, como descrever verdadeiramente o fato de fazer parte de uma descoberta tão importante e apaixonante? É fantástico!", escreveu entusiasmado em uma mensagem enviada por correio eletrônico.
Quanto à questão de se há vida nestes planetas, ela é quase impossível. Isso porque os planetas "estão longe demais de sua estrela", considera Gaudi.

Mapa mostra impacto de ação humana sobre oceanos

Mapa do impacto humano nos oceanos. National Science Foundation.

O mapa mostra o impacto humano nos oceanos na costa brasileira.

Um mapa feito por cientistas americanos e divulgado nesta sexta-feira na revista científica Science mostra que 41% dos oceanos do mundo foram afetados, em menor ou maior grau, pela ação humana.

Para mapear o impacto da atividade humana nos ecossistemas marítimos, os cientistas da Universidade da Califórnia em Santa Bárbara, nos Estados Unidos, fizeram uma sobreposição de 17 mapas que demonstravam o impacto de fatores diversos, como a pesca, a poluição e a mudança climática.

Os mapas foram feitos com base em um estudo que analisou o impacto dos seres humanos em ecossistemas como os recifes de corais, as colônias de algas marinhas, plataformas continentais e os oceanos profundos.

O mapa mostra que as áreas mais afetadas pelo impacto humano são o Mar do Norte, Mar da China Oriental e Meridional, Mar do Caribe, a costa leste da América do Norte, os mares Mediterrâneo e Vermelho,o Golfo Pérsico, o Mar de Bering e várias regiões do Pacífico Oeste.

O estudo indica ainda que as áreas menos afetadas são aquelas próximas aos pólos.

"Este projeto nos permite começar a ver o cenário do impacto dos humanos nos oceanos", diz Ben Halpern, que liderou o estudo.

"Os resultados mostram que, somados, os impactos individuais revelam uma situação muito pior do que imagino que as pessoas esperavam. Certamente foi uma surpresa para mim", afirma.

O mapa mostra as áreas mais afetadas em vermelho.
Mapa do impacto humano nos oceanos. National Science Foundation.


Segundo os cientistas, a influência dos humanos varia de forma significativa de acordo com cada ecossistema. Nas áreas mais afetadas, por exemplo, há grande concentração de recifes de coral, algas marinhas, mangues e montanhas marinhas.

Já os ecossistemas menos afetados são áreas de oceanos abertos e onde o fundo do mar é mais liso.

O mapa revela que em grande porção da costa brasileira, o impacto dos humanos é "médio alto", o que indicaria uma influência de 4,95 até 8,47%.

No entanto, enquanto algumas áreas na costa sul do Brasil o impacto aparece mais ameno, uma grande faixa da costa sudeste do país revela um impacto alto, maior que 15,52%.


A pesquisa envolveu quatro etapas. Na primeira, os cientistas desenvolveram técnicas para quantificar e comparar o impacto das atividades humanas em diferentes ecossistemas.

Na segunda etapa, a distribuição dos ecossistemas e das influências humanas foi analisada. Os cientistas então combinaram as duas informações – a distribuição e o impacto – para determinar "os índices do impacto humano" para cada região do mundo.

Finalmente, os cientistas usaram estimativas sobre as condições dos ecossistemas marítimos já disponíveis para fundamentar ainda mais os índices levantados pela pesquisa.

Os cientistas afirmam que, apesar dos esforços, o mapa ainda é incompleto, já que os dados sobre algumas atividades humanas ainda é escasso.


Apesar do cenário revelado pela pesquisa, os cientistas sugerem que ainda há tempo para tentar preservar os oceanos.

"Há certamente espaço para a esperança", diz Carrie Kappel, que participou do estudo. "Com esforços para proteger as porções dos oceanos que ainda continuam puras, temos uma boa chance de preservar estas áreas em boas condições", afirma.

De acordo com o estudo, o mapa poderá servir como referência para o desenvolvimento de políticas de conservação e manutenção, além de oferecer informações sobre o impacto de certas atividades.

"O homem sempre usará os oceanos para recreação, extração de recursos e outras atividades comerciais, como o transporte marítimo. O que precisamos é fazer isso de forma sustentável para que os oceanos continuem saudáveis e continuem a nos oferecer os recursos que precisamos", conclui Halpern.

Light echoes reveal the distance to a star

Astronomers calibrate the distance scale of the universe.
Provided by ESO
The nebula around the Cepheid star RS Pup undoubtedly holds a wealth of information about the mass-loss history of this star. It will thus be instrumental to understand the evolution of Cepheids. ESO [View Larger Image]
February 11, 2008
Taking advantage of the presence of light echoes, a team of astronomers have used an ESO telescope to measure, at the one percent precision level, the distance of a Cepheid, a class of variable stars that constitutes one of the first steps in the cosmic distance ladder.

"Our measurements with ESO's New Technology Telescope at La Silla allow us to obtain the most accurate distance to a Cepheid," says Pierre Kervella, lead author of the paper reporting the result.

Cepheids are pulsating stars that have been used as distance indicators since almost a hundred years ago. The new accurate measurement is important as, contrary to many others, it is purely geometrical and does not rely on hypotheses about the physics at play in the stars themselves.
The determination of the distance to RS Pup, following the method of the American astronomer Robert Havlen, is based on the measurement of the phase difference between the variation of the star and the variation of isolated nebular features. This artist's illustration is not to scale. ESO [View Larger Image]
The team of astronomers studied RS Pup, a bright Cepheid star located towards the constellation of Puppis the Stern and easily visible with binoculars. RS Pup varies in brightness by almost a factor of five every 41.4 days. It is 10 times more massive than the Sun, 200 times larger, and on average 15,000 times more luminous.

RS Pup is the only Cepheid to be embedded in a large nebula, which is made of very fine dust that reflects some of the light emitted by the star.

Because the luminosity of the star changes in a very distinctive pattern, the presence of the nebula allows the astronomers to see light echoes and use them to measure the distance of the star.

"The light that traveled from the star to a dust grain and then to the telescope arrives a bit later than the light that comes directly from the star to the telescope," explains Kervella. "As a consequence, if we measure the brightness of a particular, isolated dust blob in the nebula, we will obtain a brightness curve that has the same shape as the variation of the Cepheid, but shifted in time."
This artist's impression shows the location of the Cepheid star RS Pup in our galaxy, as determined by the astronomers using data from ESO's NTT. ESO [View Larger Image]
This delay is called a light echo, by analogy with the more traditional echo, the reflection of sound by, for example, the bottom of a well.

By monitoring the evolution of the brightness of the blobs in the nebula, the astronomers can derive their distance from the star: it is simply the measured delay in time, multiplied by the velocity of light (300 000 km/s). Knowing this distance and the apparent separation on the sky between the star and the blob, one can compute the distance of RS Pup.

From the observations of the echoes on several nebular features, the distance of RS Pup was found to be 6,500 light-years, plus or minus 90 light-years.

"Knowing the distance to a Cepheid star with such an accuracy proves crucial to the calibration of the period-luminosity relation of this class of stars," says Kervella. "This relation is indeed at the basis of the distance determination of galaxies using Cepheids."

RS Pup is thus distant by about a quarter of the distance between the Sun and the center of the Milky Way. RS Pup is located within the Galactic plane, in a very populated region of our galaxy.

RedLIADA No. 406: InfoLIADA con el "Projeto Eclipse Total da Lua na noite de 20 para 21 de fevereiro de 2008"


AstroNáutica- Efemérides

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"Semper Observandum"

RedLIADA - La Red de Observadores
Liga Iberoamericana de Astronomía

Edición Electrónica No. 406 - Domingo 17 de Febrero de 2008
Coordinada por ALDA - Asociación Larense de Astronomía de Barquisimeto (VE)
y por la LIADA - Liga Iberoamericana de Astronomía (AR)

Editores Responsables:
Jesús Guerrero Ordáz (VE) y Jorge Coghlan (AR)
Visite las páginas y

RedLIADA es distribuída a más de 9000 lectores de 47 Foros Iberoamericanos
de Astronomía desde el Observatorio CODE de Santa Fe (AR)

ASOCIESE a la LIADA. Informese en



Projeto Eclipse Total da Lua na noite de 20 para 21 de fevereiro de 2008

Como parte dos projetos da Seção de Ensino e Divulgação de Astronomia da LIADA estamos propondo projetos para estudantes, professores e público em
geral a respeito do Eclipse da Lua da noite de 20 para 21 de fevereiro.
Mais uma vez é uma grande oportunidade para fazer chegar às pessoas de modo
geral e da melhor maneira, a oportunidade de observarem os fenômenos do céu
dispondo de explicações a respeito.
Caso tenham disponibilidade para escrever artigos, dar entrevistas para
jornal, rádio e televisão, realizar palestras, exposições ou sessões de observação, aqui vão algumas sugestões.
A carta do eclipse e a ilustração do fenômeno com horários em tempo universal (NASA) estão em:

Solicitamos aos interessados em projetos de ensino e divulgação de Astronomia que se utilizem o espaço do Foro da LIADA para relatar seus projetos.
Mais uma vez solicito que nos enviem os resultados desses projetos. Caso essas informações sejam úteis, por favor, relate-nos suas atividades para
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Estamos interessados em estimular iniciativas deste tipo e contá-las como projetos da LIADA.
Gostaríamos muito de saber o alcance de nossas iniciativas!

Paulo Sergio Bretones
Seção de Ensino e Divulgação de Astronomia


- El lunes 18, en la madrugada, la conjunción de Pólux con la Luna.
- El martes 19, en la madrugada, la Luna en el cúmulo estelar abierto "Pesebre".
- El miércoles 20, en la noche, la conjunción de la Luna con Regulo.
- El miércoles 20, en la noche, el eclipse total de Luna.
- El jueves 21, en la madrugada, la conjunción de Saturno con la Luna.
- El viernes 22, en la noche, el máximo de la lluvia de meteoros Delta Leónidas (DLE).
- El domingo 24, en la noche, la conjunción de Espiga con la Luna.

- El cometa 17P/Holmes, en la constelación de Perseo (5m,0).
- El cometa 8P/Tuttle, en la constelación de Horologium (6m,0).
- El cometa 46P/Wirtanen, en la constelación de Aries (8m,5).
- El cometa C/2007 T1 (McNaught), en la constelación de Dorado (9m,0).

- El viernes 22, en la madrugada, el tránsito de la sombra de Ganímedes.
- El domingo 24, Saturno en Oposición.



13 de febrero de 2008.
Según los nuevos datos de la sonda espacial Cassini, Titán, la mayor luna de Saturno posee cientos de veces más hidrocarburos líquidos que la Tierra. Esta conclusión es impresionante si se toma en cuenta que Titán es apenas más grande que el planeta Mercurio. Según los investigadores, la luna es una fábrica de hidrocarburos de tamaño planetario. En lugar del agua, inmensas cantidades de químicos orgánicos se precipitan hacia la superficie de la luna, depositándose en inmensos lagos de metano y etano líquido. Moléculas sólidas con base de carbono, también se alojan en las dunas ecuatoriales de Titán. Carl Sagan acuñó el término "tholins" para describir los químicos prebióticos y se espera que las dunas de Titán estén conformadas por ellos. Los Tholines son esenciales para el surgimiento de organismos con base en el carbono. Las nuevas observaciones de la sonda Cassini apuntarán hacia la cuantificación de estos compuestos y mantendrán en vilo a los físicos planetarios y biólogos.
Más información en:



14 de febrero de 2008.
La continua búsqueda de planetas extrasolares le está permitiendo a los astrónomos a encontrar sistema planetarios, cada vez más parecidos al nuestro. Investigadores, haciendo uso del sistema OGLE (Optical Gravitational Microlensing Equipment - Equipo Óptico de Microlentes Gravitacionales) reportarán en la revista "Science" del 15 de febrero, una serie de observaciones realizadas el pasado 28 de marzo de 2006, en donde lograron detectar, en una estrella situada a unos 5.000 años-luz, unos planetas de tamaños similares a Júpiter y Saturno.
Más información en:

14 de febrero de 2008.
Uno de los problemas que se tiene con las Supernovas, es que no se sabe en donde va a ocurrir una: sólo son detectadas al momento del estallido, cuando su luminosidad se incrementa violentamente. Pero para los astrofísicos ya es demasiado tarde. Ahora, un equipo de astrónomos europeos parece haber tenido la suficiente suerte como para haber descubierto a la estrella precursora de una Supernova.
El equipo de astrónomos, buscando evidencias de sistema binarios, revisó los archivos del telescopio espacial de Rayos X, Chandra, y logró obtener imágenes en donde se observa la estrella precursora de la Supernova SN2007on. La misma estalló siguiendo la característica de una supernova tipo Ia, en donde una estrella enana blanca orbita a otra estrella. La enana blanca se alimenta extrayendo materia de la estrella compañera, hasta que obtienen la masa de 1,44 veces la de nuestro Sol, estallando.
Más información en:

14 de febrero de 2008.
Aprovechando el acercamiento del asteroide, el pasado 11 de febrero, los astrónomos que trabajan con el radiotelescopio de Arecibo, Puerto Rico, realizaron un estudio detallado del mismo, descubriendo que es triple. El asteroide denominado 2001 SN263, descubierto el 19 de septiembre de 2001, por el sistema automatizado de cacería de asteroides LINEAR (Lincoln Near Earth Asteroid Research – Búsqueda Lincoln de Asteroides Cercanos a la Tierra), consta de un asteroide principal, de forma esférica, de unos 2 km de diámetro y dos satélites de un kilómetro y 3000 metros, respectivamente.
El asteroide es el primer objeto triple, cercano a la Tierra.
Más información en:



13 de febrero de 2008.
Tras una caminata espacial de casi ocho horas, realizada por los astronautas Stanley Love y Rex Walheim, se culminó la instalación del laboratorio Columbus (de la Agencia Espacial Europea) en la Estación Espacial Internacional.
Lo primero que instalaron los astronautas fue la agarradera que permitiese asirlo con el brazo robot. Después, los astronautas Leland Melvin, Dan Tani y Leopold Eyharts, lograron extraerlo de la bodega de carga del transbordador y llevarlo a su sitio.
Antes de empezar a mover el Columbus, los astronautas Love y Walheim prepararon los cables de datos y de electricidad del módulo para conectarlos a la Estación Espacial Internacional. Una vez instalado en su posición, los astronautas europeos Leopold Eyharts (Francia) y Hans Schlegel (Alemania) fueron los primeros ocupantes del Columbus.
Más información en:

13 de febrero de 2008.
Las partículas altamente energéticas generadas por los destellos solares, son peligrosas para la salud de los astronautas en órbita de la Tierra y los sensibles circuitos electrónicos de los satélites.
De aquí que se esté buscando monitorear en tiempo real la producción de este tipo de partículas, ya que se está iniciando un nuevo ciclo de actividad solar.
Para este trabajo, se está planteando usar el Observatorio Solar Heliosférico (SOHO), ubicándolo en un punto de gravedad muerta entre el Sol y la Tierra, el primer punto de Lagrange (Lagrange 1), a 1,5 Millones de Km de la Tierra y realizar este monitoreo.
Más información en:

14 de febrero de 2008.
La armada de los Estados Unidos está planeando dispararle un misil al satélite espía de su país, que se dañó poco después de su lanzamiento, en diciembre de 2006. Según la nota de prensa, no solo se teme que restos del gran satélite puedan sobrevivir al reingreso a la atmósfera, sino que uno de los propulsores que utiliza, la hidracina, es altamente nociva a la salud. Por consiguiente, los planes se encuentran en marcha con la finalidad de destruir en órbita al satélite, en lugar de permitir que ingrese a la atmósfera y se incinere en la reentrada, a finales de febrero, comienzos de marzo.
Más información en:




Tiempos en Hora Legal de Venezuela (HLV) y Tiempo Universal (UT).

Se observa en las madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Capricornio. Su salida ocurre a las 5:01 HLV (9:31 UT).

Se observa en las madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Capricornio. Su salida ocurre a las 4:45 HLV (9:15 UT).

Se observa en las noches y madrugadas, hacia el cenit del cielo. Se encuentra en la constelación de Tauro (Toro). Su puesta ocurre a las 2:17 HLV (6:47 UT).

Se observa en las madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Sagitario. Su Salida ocurre a las 3:25 HLV (7:55 UT).

Se observa en las noches y madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Leo (León). Su Salida ocurre a las 18:32 HLV (23:02 UT).

(Del 18 al 24 de febrero de 2008)
Tiempos en Hora Legal de Venezuela (HLV) y Tiempo Universal (UT).

Lunes 18
18 – Eclipse de Io. Desaparece 8:48,4 UT.
18 – Maniobra de ajuste orbital de la sonda Cassini (OTM-145).
18 – Mercurio Estacionario. 14:30 HLV (19 UT).
18 – Meridiano Central de Júpiter, Sistema II, 0 UT; 96,0º
18 – Pólux 3,8º al Norte de la Luna. 3:30 HLV (8 UT).
18 - 78 aniversario (1930) del descubrimiento de Plutón por Clyde Tombaugh.
18 – 84 aniversario (1924) del nacimiento de Humberto Fernández Morán, científico venezolano que desarrollo de microscopía electrónica.
18 – 807 aniversario (1201) del nacimiento de Nasir al-Tusi, científico y matemático árabe que modificó el modelo de Claudio Ptolomeo.
Martes 19
19 – Luna en el Pesebre. 4:00 HLV (8:30 UT).
19 – Meridiano Central de Marte, 0 UT; 74,6º
19 – Tránsito de Io. Egreso 9:06,0 UT.
19 – Tránsito de la sombra de Io. Egreso 8:10,6 UT.
19 – 149 aniversario (1859) del nacimiento de Svante Arrhenius, científico sueco postulador de la Teoría de la Panspermia (vida transportada por cometas).
19 - 535 aniversario (1473) del nacimiento de Nicolás Copérnico, matemático y astrónomo polaco que desarrolló la teoría heliocéntrica del Sistema Solar.

Miércoles 20
20 – Inicio del Día Juliano 2.454.516,5
20 – Conjunción de la Luna con Regulo. 19:30 HLV (0 UT).
20 – Eclipse Total de Luna. Visible en toda Latinoamérica 20:05 HLV (0:35 UT).
20 – Los anillos de Urano cruzan el plano ecuatorial.
20 – Luna en el Nodo Descendente de su órbita. 15:30 HLV.
20 – Luna Llena. 23:01 HLV (3:31 UT).
20 – Meridiano Central de Júpiter, Sistema II, 0 UT; 36,3º
20 – Salida de la Luna. 18:03 HLV.
20 – Sobrevuelo distante de la sonda Cassini a las lunas Pan, Prometeo, Pandora y Jano.
20 – 22 aniversario (1986) del lanzamiento de la Estación Espacial MIR (Unión Soviética)
20 – 43 aniversario (1965) del impacto de la sonda Ranger 8 en la Luna, después de fotografiar los posibles sitios de alunizaje de la misión Apolo.
20 - 46 aniversario (1962) del lanzamiento de la cápsula Friendship 7 (Estados Unidos) con el astronauta John Glenn. Dio tres vueltas a la Tierra.
20 – 164 aniversario (1844) del nacimiento de Ludwig Boltzmann, químico austriaco que desarrolló con Joseph Stephan, la teoría Cinética de los gases.

Jueves 21
21 – Eclipse de Europa. Desaparece 10:15,8 UT.
21 – Meridiano Central de Marte, 0 UT; 55,9º
21 – Puesta de Marte. 2:15 HLV.
21 – Salida de Júpiter. 3:22 HLV.
21 – Salida de la Luna. 18:52 HLV.
21 – Salida de Mercurio. 4:58 HLV.
21 – Salida de Saturno. 18:27 HLV.
21 – Salida de Venus. 4:45 HLV.
21 – Saturno 2,5º al Norte de la Luna. 5:30 HLV (10 UT).

Viernes 22
22 – La sonda Cassini sobrevuela Titan.
22 - Máximo de la lluvia de meteoros Delta Leónidas (DLE). Activa del 15feb al 10mar. Radiante AR=11h12m dec=+16º. THZ: 3 meteoros/hora.
22 – Meridiano Central de Júpiter, Sistema II, 0 UT; 336,5º
22 – Salida de la Luna. 19:40 HLV.
22 – Tránsito de la sombra de Ganímedes. Egreso 10:04,0 UT.
22 – 151 aniversario (1857) de Heinrich Rudolf Hertz, físico alemán que en 1888 demostró la existencia de las ondas electromagnéticas.
22 – 376 aniversario (1632) de la publicación, por Galileo Galilei de su libro "Dialogo concerniente a los dos sistemas del mundo".

Sábado 23
23 – Meridiano Central de Marte, 0 UT; 37,3º
23 – Salida de la Luna. 20:27 HLV.
23 – Tránsito de Europa. Egreso 10:03,5 UT.
23 – Tránsito de la Gran Mancha Roja de Júpiter; 5:13 HLV.
23 – Tránsito de la sombra de Europa. Egreso 8:05,8 UT.
23 - 21 aniversario (1987) de la explosión de la Supernova 1987A, la explosión más brillante en 383 años. Fue descubierta visualmente por Ian Shelton, en Chile.
23 – 425 aniversario (1583) del nacimiento de Jean-Baptiste Morin, matemático y astrónomo francés, que intentó resolver, en 1634, el problema de la Longitud Terrestre.

Domingo 24
24 – Espiga 2,3º al Norte de la Luna. 23:30 HLV (4 UT).
24 – Meridiano Central de Júpiter, Sistema II, 0 UT; 276,8º
24 – Salida de la Luna. 21:13 HLV.
24 – Saturno en Oposición. 5:30 HLV (10 UT).
24 - 40 aniversario (1968) de la publicación del descubrimiento del primer Pulsar, por Jocelyn Bell.
24 – 142 aniversario (1866) del nacimiento de Pyotr Nikolaevich Lebedev, físico ruso que hizo la primera confirmación cuantitativa de la teoría electromagnética de Maxwell. Un cráter en la Luna lleva su nombre.
24 – 426 aniversario (1582) del anuncio del papa Gregorio XIII del Calendario Gregoriano.



Con motivo de celebrarse el próximo domingo 24 de febrero, el 40 aniversario (1968) de la publicación de la noticia con el descubrimiento del primer Pulsar, por Jocelyn Bell, traemos a colación información básica sobre este tipo de objeto celeste.

El primer pulsar fue detectado en la constelación de Vulpécula (Raposa) por la entonces tesista de física, Jocelyn Bell, haciendo uso del radiotelescopio Mullard de la Universidad de Cambridge, el 06 de agosto de 1967. Se le designó con el código CP1919. La publicación del descubrimiento se hizo con un artículo en la revista Nature (N° 217), el 24 de febrero de 1968. El artículo estaba signado por A. Hewish, S. J. Bell, J. D. H. Pilkington, P. F. Scott y R. A. Collins

Los astrónomos distinguen tres tipos de pulsar, siendo clasificados por la forma cómo adquieren su energía.

1. Pulsar potenciados por rotación, en donde la pérdida de energía rotatoria de la estrella impulsa la radiación.

2. Pulsar potenciados por acreción (la mayoría), donde la energía gravitacional de la materia absorbida (o acretada), es la fuente de la energía.

3. Magnetars, dónde el decaimiento de un poderoso campo magnético potencia la radiación.

* Inicialmente los pulsar fueron designados por las iniciales del observatorio desde donde se hizo el descubrimiento, seguido de las coordenadas en Ascensión Recta del objeto (con época al equinoccio de 1950). Ejemplo CP 1919, el primer pulsar descubierto.

* El incremento en los descubrimientos hizo que se adoptara la nomenclatura PSR (acrónimo de Pulsating Source of Radio) seguido de las coordenadas en Ascensión recta y declinación. Ejemplo: PSR 0531+21.

* Para los pulsar descubiertos antes de 1993, se agrega una "B" en su denominación, informando que sus coordenadas se expresan con el equinoccio de 1950. Ejemplo: PSR B1919+21.

* Para los pulsar descubiertos después de 1993, se agrega una "J" para indicar que sus coordenadas se expresan en el equinoccio del 2000. Ejemplo: PSR J1921+2153.

* Pulsars muy cercanos, se les agrega una letra al final de las coordenadas. Ejemplo: PSR 0021-72C y PSR 0021-72D.

* El primer pulsar: CP 1919 o PSR 1919+21. Emite un pulso cada 1,337 segundos.

* El primer pulsar binario: PSR 1913+16. Su órbita decae a una razón predicha por la radiación gravitacional de la Teoría General de la Relatividad.

* El primer pulsar de milisegundos: PSR B1937+21.

* El pulsar de milisegundos más brillante: PSR J0437-4715.

* El primer pulsar de rayos X: Cen X-3.

* El primer pulsar de acreción con emisión de rayos X, con período de milisegundos: SAX J1808.4-3658.

* El primer pulsar al que se le descubre un planeta extrasolar: PSR B1257+12.

* El primer sistema doble de pulsar binarios: PSR J0737−3039.

* El magnetar que produce el destello más largo en nuestra galaxia: SGR 1806-20 (grabado el 27 de diciembre de 2004.

* El pulsar con la mayor velocidad de rotación: PSR J1748-2446ad (716 Hz).

* El pulsar más cercano a la Tierra: PSR J0108-1431 (constelación de Ballena a 280 años-luz).

A tutorial on Radio Pulsar (Jocelyn Bell):

Información en wikipedia:


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