New light on dark energy

Probing the cosmic web of the universe helps astronomers better understand dark energy and cosmic expansion.

Provided by the ESO

This image is a snapshot from a computer simulation of the formation of large-scale structures in the universe, showing a patch of 100 million light-years and the resulting coherent motions of galaxies flowing towards the highest mass concentration in the centre. The snapshot refers to an epoch about 10 billion years back in time. The color scale represents the mass density, with the highest density regions painted in red and the lowest in black. The tiny yellow lines describe the intensity and direction of the galaxy's velocities. Klaus Dolag/VVDS/ESO [View Larger Image] February 4, 2008 Astronomers have used ESO's Very Large Telescope to measure the distribution and motions of thousands of galaxies in the distant universe. This opens fascinating perspectives to better understand what drives the acceleration of the cosmic expansion and sheds new light on the mysterious dark energy that is thought to permeate the universe. "Explaining why the expansion of the universe is currently accelerating is certainly the most fascinating question in modern cosmology," says Luigi Guzzo, lead author of a paper in which the new results are presented. "We have been able to show that large surveys that measure the positions and velocities of distant galaxies provide us with a new powerful way to solve this mystery." Astronomers made the stunning discovery 10 years ago that the universe is expanding at a faster pace today than it did in the past. "This implies that one of two very different possibilities must hold true," explains Enzo Branchini, member of the team. "Either the universe is filled with a mysterious dark energy which produces a repulsive force that fights the gravitational brake from all the matter present in the universe, or, our current theory of gravitation is not correct and needs to be modified, for example by adding extra dimensions to space." Current observations of the expansion rate of the universe cannot distinguish between these two options, but the international team of 51 scientists from 24 institutions found a way that could help in tackling this problem. The technique is based on a well-known phenomenon, namely the fact that the apparent motion of distant galaxies results from two effects: the global expansion of the universe that pushes the galaxies away from each other and the gravitational attraction of matter present in the galaxies' neighborhood that pulls them together, creating the cosmic web of large-scale structures.

This image shows maps of the distribution of galaxies in the VVDS-Wide survey, showing the presence of large-scale structures. The colors indicate the density of galaxies, going from green to blue, the latter being the densest regions. The data have been cut into three cones, from the closest galaxies (bottom) to the farthest. The sample includes galaxies whose light travelled between 1.3 and 8.5 billion years. ESO [View Larger Image] "By measuring the apparent velocities of large samples of galaxies over the last 30 years, astronomers have been able to reconstruct a three-dimensional map of the distribution of galaxies over large volumes of the universe. This map revealed large-scale structures such as clusters of galaxies and filamentary superclusters," says Olivier Le Fevre, member of the team. "But the measured velocities also contain information about the local motions of galaxies; these introduce small but significant distortions in the reconstructed maps of the universe. We have shown that measuring this distortion at different epochs of the universe's history is a way to test the nature of dark energy." Guzzo and his collaborators have been able to measure this effect by using the VIMOS spectrograph on Melipal, one of the four 8.2-meter telescopes that is part of ESO's VLT. As part of the VIMOS-VLT Deep Survey (VVDS), spectra of several thousands of galaxies in a 4-square-degree field (or 20 times the size of the full Moon) at epochs corresponding to about half the current age of the universe (about 7 billion years ago) were obtained and analyzed. "This is the largest field ever covered homogeneously by means of spectroscopy to this depth," says Le Fevre. "We have now collected more than 13,000 spectra in this field and the total volume sampled by the survey is more than 25 million cubic light-years." The astronomers compared their result with that of the 2dFGRS survey that probed the local universe, i.e. measures the distortion at the present time. Within current uncertainties, the measurement of this effect provides an independent indication of the need for an unknown extra energy ingredient in the 'cosmic soup', supporting the simplest form of dark energy, the so-called cosmological constant, introduced originally by Albert Einstein. The large uncertainties do not yet exclude the other scenarios, though. "We have also shown that by extending our measurements over volumes about ten times larger than the VVDS, this technique should be able to tell us whether cosmic acceleration originates from a dark energy component of exotic origin or requires a modification of the laws of gravity," says Guzzo. "VIMOS on the VLT would certainly be a wonderful tool to perform this future survey and help us answer this fundamental question. This strongly encourages scientists to proceed with even more ambitious surveys of the distant Universe," says Le Fevre.

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A fé na ciência

07/02/2008
Minha coluna da semana passada, em que defendi a ciência de ataques neocriacionistas e "humanitários", gerou mais controvérsia do que eu poderia supor. Leitores questionaram-me acerca da eugenia, das bases epistemológicas do darwinismo, do caráter laico do Estado e até da validade do discurso científico. Acreditar na ciência, sugeriram alguns, exige tanta fé quanto crer em Deus.
Será? Aceito a provocação, de modo que vou tentar mostrar hoje por que a ciência não é uma religião.
Comecemos pelas semelhanças. Como qualquer um que já abriu um livro de epistemologia sabe, a ciência busca seus fundamentos em meia dúzia de postulados, ou seja, de premissas que, a exemplo dos dogmas religiosos, são tomadas como auto-evidentes, isto é, consideradas verdadeiras sem necessidade demonstração. Para o monoteísmo, sentenças como "Deus criou o mundo" constituem verdades inquestionáveis. Já na ciência, quem desempenha esse papel são princípios como o de identidade e o de não-contradição. O primeiro afirma que, se A=A, então A=A, e o segundo reza que, se A=não-B, na ocorrência de A não ocorre B, e vice-versa. Convenhamos que não são idéias revolucionárias e nem mesmo particularmente brilhantes, mas já aí começam a emergir algumas das diferenças entre ciência e religião.
Um juízo como "Deus criou o mundo" é contingente, ou seja, eu posso, ainda que apenas no plano da lógica, conceber um mundo criado pelo acaso, pelo diabo ou até pelo presidente Lula ("nunca antes na história desse universo..."). Já os postulados científicos são em tese mais fortes, pois lidam com juízos necessários: para imaginar que uma coisa seja diversa dela mesma, eu preciso renegar ou pelo menos suspender os fundamentos da lógica.
Até aqui, a vantagem é da religião. Ela já está emitindo pareceres sobre o mundo, enquanto a ciência permanece presa ao reino das abstrações matemáticas. Se queremos que a ciência fale sobre o mundo --e, para possuir alguma utilidade, ela tem de fazê-lo--, precisamos dar um passo temerário. Precisamos autorizá-la a lidar com induções, ou seja, admitir que, partindo de casos particulares observados, proceda a generalizações. Exemplo: o sol nasceu hoje e em todos os dias que antecederam o dia de hoje, logo, o sol nascerá também amanhã. Ao aceitar esse tipo de raciocínio, conquistamos o direito de proferir juízos sobre a realidade física, mas sacrificamos o plano sólido das certezas matemáticas no qual antes caminhávamos. Com efeito, o fato de o sol ter nascido todos os dias no passado não encerra a garantia lógica de que também nascerá amanhã. Isso é no máximo muito provável, mas de maneira alguma necessário.
Por paradoxal que pareça, esse súbito rebaixamento do grau de certeza com que lidam as ciências é uma excelente notícia. Juízos científicos tornam-se daqui em diante verdades provisórias. Não contam mais com nenhum tipo de garantia lógica, uma vez que se baseiam em meros encadeamentos entre experiências passadas e raciocínios generalizantes --processo que sabemos falível e propenso a erro.
Assim a ciência, diferentemente da maioria das religiões, perde o direito até mesmo de pretender afirmar verdades acabadas. Tudo que ela pode fazer é gerar hipóteses a ser testadas e refutadas empiricamente. Quando essas suposições passam muito tempo sem ser cabalmente desmentidas, como é o caso da evolução mediante seleção natural, dizemos que são corroboradas. É claro que esse é um processo em aberto, pois o fato de não terem sido refutadas até aqui não encerra a garantia de que não o serão amanhã. Isso é o mais perto da "prova" que a ciência pode chegar.
Essa precariedade epistemológica cerca toda a ciência, do neordarwinismo, à chamada lei da gravidade. Embora não ouçamos com muita freqüência gente afirmando que a gravidade é "só uma teoria", é exatamente isso que ela é. O que o neocriacionismo travestido de 'design inteligente' faz é embaralhar o sentido de teoria em suas acepções fraca (a do dia a dia) e forte (epistemológica) para, em meio à confusão conceitual, semear seus pressupostos algo dogmáticos. O fato de o neoevolucionismo apresentar, como toda teoria, algumas lacunas de maneira alguma nos autoriza a inferir um deus logo à primeira dificuldade.
A incerteza e a subseqüente maleabilidade da ciência vão ainda mais longe. No limite, ela admite até que seus próprios "dogmas" sejam revistos. Algumas hipóteses da mecânica quântica, por exemplo, vão de encontro ao princípio da não-contradição. Seria como se a religião negasse Deus em determinadas situações. Os dogmas da ciência se articulam de maneira tão particular que a tornam o menos dogmático dos discursos.
É claro que estamos aqui falando na teoria. No mundo real, encontraremos cientistas tão fanáticos quanto o mais exaltado dos padres inquisidores. Encontraremos indivíduos que de bom grado mandariam queimar todos os que ousassem desafiar o "mainstream" científico. Ainda assim, é digno de nota o fato de que, enquanto a religião só existe com o dogma, a ciência como método trabalha para falsear idéias aceitas e noções estabelecidas --em uma palavra, para falsear dogmas. Não acho que eu avance muito o sinal quando afirmo que essa diferença ajuda a explicar o fato de que mesmo o mais tacanho positivismo produziu menos fogueiras do que a mais tolerante das religiões.
Podemos eventualmente nos deparar com um cético radical, para o qual dogmas, postulados e axiomas são todos indiscerníveis entre si e valem a mesma coisa, isto é, nada. É oportuno lembrar que o filósofo e matemático austríaco Kurt Gödel (1906-78), com seus teoremas da incompletude, se não colocou em xeque, ao menos criou dificuldades para a própria lógica formal. Mas, mesmo nesse registro hiperbólico, a ciência apresenta vantagens sobre as religiões.
Ela tem como subproduto tecnologias, que constituem uma "prova" indireta não tanto de sua "exatidão", mas pelo menos de que o métodos científico leva a algum lugar. O foguete que eu construo com base em minhas idéias sobre a física, desde que corretamente lançado, me levará à Lua quer eu seja judeu, ateu, católico, muçulmano ou corintiano. Já com as religiões, as mesmas ações que levariam o partidário de uma ao paraíso atiram-no no inferno segundo a doutrina da outra.
Tomemos uma dessas medidas indiretas, a evolução da expectativa de vida ao nascer. Estima-se que o tempo médio de vida do homem de Neanderthal fosse de 20 anos. No Paleolítico Superior, o Homo sapiens chegava a algo como 33 anos. Na Idade do Bronze, com o advento da agricultura e o aumento do tamanho dos assentamentos humanos (mais doenças e guerras mais mortíferas), a expectativa de vida cai para 18 anos. Noções de higiene desenvolvidas por gregos e romanos (saneamento) conseguem elevar a média para 36-45 (Grécia clássica) 20-30 (Roma clássica). Mas, no século 20 e início do 21, na chamada era científica, assistimos a um um verdadeiro salto da esperança de vida, que atinge os 67 anos (média global), quase 80 se considerarmos só os países desenvolvidos. Um cético hiperbólico diria que a correlação nada prova. Um dogmático religioso diria que este é o plano de Deus. Já eu prefiro atribuir tal avanço a subprodutos da ciência como antibióticos, vacinas e grandes excedentes agrícolas. Em poucas palavras, embora a ciência esteja conosco de forma razoavelmente bem estabelecida há apenas 200 anos, já fez mais pelo bem-estar da humanidade do que todas as rezas e mandingas de religiosos durante milênios.

Hélio Schwartsman, 42, é editorialista da Folha. Bacharel em filosofia, publicou "Aquilae Titicans - O Segredo de Avicena - Uma Aventura no Afeganistão" em 2001. Escreve para a Folha Online às quintas. E-mail: helio@folhasp.com.br Leia as colunas anteriores

Testing a Europa Probe Prototype

Written by Nancy Atkinson


While NASA doesn't have any definite plans to send a probe to study Jupiter's moon Europa, many planetary scientists consider the exploration of this enticing moon to be a high priority. Evidence from the Voyager and Galileo spacecraft suggests Europa contains a deep ocean of salty water under an icy outer shell. NASA is, however, helping to fund a prototype of an underwater autonomous vehicle to investigate ice covered lakes here on Earth, to demonstrate if such a vehicle could operate in an environment similar to Europa. The next test of the vehicle will take place Feb. 12-15, 2008 in Lake Mendota on the campus of the University of Wisconsin, Madison.

The Environmentally Non-Disturbing Under-ice Robotic Antarctic Explorer, also known as Endurance, will swim untethered under ice, and collect data to create three-dimensional maps of underwater environments. The probe also will look at the conditions in those environments and take samples of microbial life. Later this year, researchers plan to ship the probe to a permanently frozen lake in Antarctica for more operations. The probe is a follow-up to the Deep Phreatic Thermal Explorer, a NASA-funded project that completed a series of underwater field tests in Mexico in 2007.
"We're using extreme environments on Earth as our laboratory," says Peter Doran, associate professor at the University of Illinois at Chicago. "Ice-covered lakes … are good, small-scale analogs to what we might find on Europa."

Mendota Lake is only 25 meters deep, while the lake in Antarctica, West Lake Bonney is 40 meters deep. Scientists believe that Europa's ocean could be up to 100 kilometers deep.
Hot water drills will bore a hole for Endurance to enter the water. If all goes well, the probe will be tested again in 2009.
But many hurdles remain before an underwater vehicle could possibly head to Europa. Presently, Endurance is too massive to send on interplanetary travel. Scientists will also have to come up with a way to drill through Europa's icy crust and lower the sub safely through the ice.
And before a probe would be sent to land on Europa, many scientists feel that an orbiting spacecraft would be the best way to study the moon. The Jet Propulsion Laboratory is currently working on a concept called the Europa Explorer which would deliver a low orbit spacecraft to determine the presence (or absence) of a liquid water ocean under Europa's ice surface. It would also map the surface and subsurface for future exploration.
Original News Sources: NASA Press Release, Washington University Press Release

Filed under: Europa

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.

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A Stardust-Free Comet

NASA's Stardust mission has just reminded us — for the second time — that we don't know as much about comets as we thought we did.

Comets are thought to be nearly unaltered relics from the formation of the solar system, and Stardust's target, 81P/Wild 2 (pronounced vilt) was considered a perfect target. These days Wild 2 can venture fairly near the Sun (just beyond Mars's orbit). But prior to a close brush with Jupiter in 1974, its orbit was much more distant.

NASA's Stardust dashed through the dusty coma of Comet Wild 2 on January 2, 2004, and returned the tiny samples it collected to Earth on January 15, 2006.

NASA / JPL

So cosmochemists would have bet money (and maybe did) that the dust and gas coming off Wild 2 when Stardust flew through it in 2004 would be primordial building blocks, released from their deep-freeze confinement after 4½ billion years, that would unlock the key to the solar system's formation.

The smart money, it turns out, was wrong. Not long after Stardust returned to Earth in January 2006 with its precious cargo, it became clear that some of those building blocks came from a very hot kiln. Researchers found an array of minerals that formed at temperatures of at least 2,000°F (1,100°C). Not exactly "deep-freeze" conditions!

Now Stardust has stumped the scientists again. In Science for January 25th, a team led by Hope Ishii (Lawrence Livermore National Laboratory) reports that the captured cometary grains are closer matches to "an inner solar-system asteroid than an outer-solar-system comet with primitive unaltered dust."

In other words, silicate minerals that formed near the Sun were somehow transported to the outer system, where they mingled with ices to create Comet Wild 2. There are no mineral clusters untouched since the Sun first blazed to life, no infusions of exotic isotopes from distant supernovas — if it weren't so dynamically implausible, you might think Comet Wild 2 was an escapee from the asteroid belt.

Did all comets form this way? Probably not. High-flying jets have captured a host of interplanetary dust particles drifting into our atmosphere from space. These tiny treasures have the kind of primitive compositions and unique isotopic mixes that scientists had expected to find in the Stardust samples.

So maybe we just need to go sample another comet (Rosetta, a European-built craft, will do so in 2014). Or maybe our theories of solar-system formation need retooling. Whatver the reason, Stardust has lots of cosmochemists scratching their collective heads right now.

Posted by Kelly Beatty, January 28, 2008

Ônibus espacial Atlantis se acopla à Estação Espacial Internacional

Publicada em 09/02/2008 às 15h56m

O Globo OnlineAgências internacionais
HOUSTON, Estados Unidos - Pouco antes do previsto, o ônibus espacial Atlantis se acoplou, neste sábado, à Estação Espacial Internacional (ISS, na sigla em inglês), pondo fim a uma viagem de dois dias. Na missão marcada por diversos adiamentos, desde 2003, e problemas técnicos que impediram a decolagem do Atlantis, a tripulação de sete astronautas leva o primeiro laboratório de pesquisa espacial permanente produzido pela Europa para o projeto internacional que deve ser concluído em 2010. ( clique e veja as fotos da Atlantis neste sábado )
A previsão é de que o ônibus espacial estivesse totalmente acoplado à ISS a partir das 18h25m (horário de Brasília). O astronauta americano Steve Frick, comanda uma tripulação, que inclui o piloto Alan Poindexter e os especialistas Leland Melvin, Rex Walheim, Stanley Love e os membros da Agência Espacial Européia (ESA) Hans Schlegel (Alemanha) e Leopold Eyharts (França). Este é a primeira viagem espacial de Poindexter, Love e Melvin. A tripulação chega à ISS comemorando o aniversário da comandante da Estação, Peggy Whitson, que completa 48 anos neste sábado.
- Nos perguntávamos se todas essas velas eram da torta de aniversário de Peggy - brincou o astronauta Kevin Ford, na estação de controle da missão, quando o ônibus espacial se aproximava da ISS.
O lançamento do Atlantis foi adiado por mais de dois meses, mas a ESA)já aguarda desde 2002 pelo envio do módulo Columbus, que custou US$ 1,9 bilhão e é a mais importante contribuição da Europa à plataforma de pesquisas espaciais.
Inicialmente a demora se deveu a um atraso no envio de um módulo russo de serviço para a estação. Depois, foi provocado por causa do acidente de 2003 com o ônibus Columbia, que fez com que os vôos de ônibus espaciais americanos passassem dois anos e meio suspensos.
Poucas semanas depois da instalação do Columbus, durante a missão de 11 dias do Atlantis, já será possível experiências, como física de fluidos e biologia, poderão ser realizadas no módulo.
Além de retomar os lançamentos neste início de ano, a Nasa anunciou na quarta-feira uma missão para estudar uma misteriosa forma de energia do Cosmos e uma ambiciosa jornada aos extremos do Sistema Solar. Também está previsto uma aproximação inédita da coroa do Sol, onde se formam os ventos solares.

The growing-up of a star

VLT decodes the innermost surroundings of a star in the maturing.

Provided by ESO

This artist's impression shows the disc of matter surrounding MWC 147. A slice has been cut to show the inner structure better. The disc extends out to 100 times the distance between the Earth and the Sun. The dust in the outer disc emits mainly at mid-infrared wavelengths, while close to the star there is also strong near-infrared emission from very hot gas. ESO [View Larger Image] February 4, 2008 Using ESO's Very Large Telescope Interferometer, astronomers have probed the inner parts of the disc of material surrounding a young stellar object, witnessing how it gains its mass before becoming an adult. The astronomers had a close look at the object known as MWC 147, lying about 2,600 light-years away towards the constellation of Monoceros (the Unicorn). MWC 147 belongs to the family of Herbig Ae/Be objects. These have a few times the mass of our Sun and are still forming, increasing in mass by swallowing material present in a surrounding disc. MWC 147 is less than half a million years old. If one associated the middle-aged, 4.6 billion year old Sun with a person in his early forties, MWC 147 would be a 1-day-old baby. The morphology of the inner environment of these young stars is however a matter of debate and knowledge of it is important to better understand how stars and their cortege of planets form. Astronomers have used the four 8.2-meter Unit Telescopes of ESO's Very Large Telescope to this purpose, combining the light from two or three telescopes with the MIDI and AMBER instruments. "With our VLTI/MIDI and VLTI/AMBER observations of MWC 147, we combine, for the first time, near- and mid-infrared interferometric observations of a Herbig Ae/Be star, providing a measurement of the disc size over a wide wavelength range," says Stefan Kraus, lead author of the paper reporting the results. "Different wavelength regimes trace different temperatures, allowing us to probe the disc's geometry on the smaller scale, but also to constrain how the temperature changes with the distance from the star." The near-infrared observations probe hot material with temperatures of up to a few thousand degrees in the innermost disc regions, while the mid-infrared observations trace cooler dust further out in the disc. The observations show that the temperature changes with radius are much steeper than predicted by the currently favored models, indicating that most of the near-infrared emission emerges from hot material located very close to the star, that is, within one or two times the Earth-Sun distance (1-2 AU). This also implies that dust cannot exist so close to the star, since the strong energy radiated by the star heats and ultimately destroys the dust grains. "We have performed detailed numerical simulations to understand these observations and reached the conclusion that we observe not only the outer dust disc, but also measure strong emission from a hot inner gaseous disc. This suggests that the disc is not a passive one, simply reprocessing the light from the star," explains Kraus. "Instead, the disc is active, and we see the material, which is just transported from the outer disc parts towards the forming star." The best-fit model is that of a disc extending out to 100 AU, with the star increasing in mass at a rate of 7 millionths of a solar mass per year. "Our study demonstrates the power of ESO's VLTI to probe the inner structure of discs around young stars and to reveal how stars reach their final mass," says Kraus.

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Mercury's "Better Half"

The Space Age was barely two years old when, in October 1959, the Soviet Union sent Luna 3 to photograph the far side of the Moon. Astronomers were ecstatic once they'd finally glimpsed the never-before-seen half of the lunar landscape. Luna 3's 40 crude images showed that the far side was different than the side facing Earth, with very few dark, basalt-filled maria.

Even when viewed in color (left), Mercury is essentially a black-and-white world. When its subtle color differences are exaggerated(right), fresher impacts appear "bluer" (less red) than the surrounding terrain. The lighter hues inside Caloris basin, 960 miles across, may hold clues to the planet's internal composition. Click on the image for a larger view.

NASA / JHU-APL / Carnegie Inst. of Washington

Planetary scientists have been likewise awaiting a chance to glimpse details on the half of Mercury that went unseen by Mariner 10 in the mid-1970s. And, thanks to Messenger's close flyby on January 14th, they've gotten a good start on filling in the blanks. They provided a few peeks at what the craft radioed to Earth during a press conference on January 30th.

Before I forget, let me note that the mission's actual name is Mercury Surface, Space Environment, Geochemistry, and Ranging — that's why everyone just calls it "Messenger."

But what's in a name? The spacecraft and all seven of its instruments really delivered. Before turning the spotlight over to the imaging specialists, principal investigator Sean Solomon noted that the planet's magnetic field — unique among planets in its similarity to Earth's — hasn't changed since Mariner 10's visit. But the sodium and hydrogen atoms found streaming away from Mercury (more so from the north half than from the south) will require more observations to puzzle out.

Carloris basin, one of the largest impacts in the solar system, was discovered by Mariner 10 during a series of flybys in 1974-75. But most of the basin was in shadow at the time. Messenger's view show that Caloris is actually 20% bigger (blue circle) than previously thought, about 960 miles across. Arrows point to a small, fresh crater and to the like-sized "spider" (seen in close-up below).

NASA / JHU-APL / Carnegie Inst. of Washington

Messenger's views are gorgeous, though they lack the color and variety seen most everywhere else in the solar system. To appreciate Mercury, ya gotta love craters — to the casual eye, that's all the pictures show. Big ones, little ones, splashy ones, dark ones, and a few double-ringed ones.

The biggest, baddest crater on Mercury — and the one most likely to reveal how this planet came to be — is Caloris basin. Mariner 10 saw only a slice of Caloris, but Messenger has now imaged all of it. At 960 miles (1,550 km) across, it's actually 20% bigger than previously thought.

Lots of curious features lie inside this Alaska-size saucer. One, nicknamed "the spider," is a 25-mile-wide crater with scores of fractures radiating away from it like bicycle spokes. It's the kind of pattern you'd get if something were pushing up on the crust from below.

This remarkable feature — nicknamed "the spider" by Messenger's science team — lies near the center of Caloris basin. A set of troughs radiates outward from a 25-mile-wide crater in a geometry unlike anything seen by Mariner 10. The troughs apparently resulted from the extension (breaking apart) of the basin's floor.

NASA / JHU-APL / Carnegie Inst. of Washington

The press conference was as interesting for what wasn't said as for what was. No one really commented on the surface composition, though I'm sure there's already plenty to say about it. And the team was mum on what they've learned about the planet's interior. (By flying by so closely, the spacecraft was yanked around by the planet's gravity in subtle yet revealing ways.)

Mercury's density is too high — there's too much iron inside it — for the planet simply to have assembled from the mix of compounds present near the Sun when the solar system formed. So planetary scientists think one of three things happened: (1) somehow Mercury came together with a paucity of lower-density silicates, the kind found abundantly in Earth's crust; (2) it endured a period of extreme heating from the young Sun, which caused many minerals to simply boil away; or (3) something really big collided with Mercury and stripped away the lion's share of its crust and mantle.

The compositional data returned by Messenger probably offer crucial clues to which of these scenarios is correct. But the Messenger scientists didn't address this subject during the press conference — and they'll have little more to say until mid-March, when they'll present a far more complete analysis at the annual Lunar & Planetary Science Conference in Houston, Texas. I'll be out in the audience, scribbling furiously.

Saturn has a 'giant sponge'

NASA/JPL NEWS RELEASE
Posted: February 6, 2008
One of Saturn's rings does housecleaning, soaking up material gushing from the fountains on Saturn's tiny ice moon Enceladus, according to new observations from the Cassini spacecraft.
"Saturn's A-ring and Enceladus are separated by 100,000 kilometers (62,000 miles), yet there¹s a physical connection between the two," says William Farrell of NASA's Goddard Space Flight Center in Greenbelt, Md. "Prior to Cassini, it was believed that the two bodies were separate and distinct entities, but Cassini¹s unique observations indicate that Enceladus is actually delivering a portion of its mass directly to the outer edge of the A-ring." Farrell is lead author of a paper on this discovery that appeared in Geophysical Research Letters January 23.
This is the latest surprising phenomenon associated with the ice geysers of Enceladus to be discovered or confirmed by Cassini scientists. Earlier, the geysers were found to be responsible for the content of the E-ring. Next, the whole magnetic environment of Saturn was found to be weighed down by the material spewing from Enceladus, which becomes plasma -- a gas of electrically charged particles. Now, Cassini scientists confirm that the plasma, which creates a donut-shaped cloud around Saturn, is being snatched by Saturn's A-ring, which acts like a giant sponge where the plasma is absorbed.
Shot from Enceladus' interior, the gas particles become electrically charged (ionized) by sunlight and collisions with other atoms and electrons. Once electrically charged, the particles feel magnetic force and are swept into the space around Saturn dominated by the planet's powerful magnetic field. There, they are trapped by Saturn's magnetic field lines, bouncing back and forth from pole to pole. The fun ends, however, if their bouncing path carries them inward toward Saturn to the A-ring. There they stick, in essence becoming part of the ring. "Once they get to the outer A-ring, they are stuck," says Farrell.
"This is an example of how Saturn's rings mitigate the overall radiation environment around the planet, sponging up low- and high-energy particles," says Farrell. By contrast, Jupiter has no dense rings to soak up high-energy particles, so that planet's extremely high radiation environment persists.
The Cassini observations confirm a prediction by John Richardson and Slobodan Jurac of the Massachusetts Institute of Technology. In the early 1990¹s, Hubble Space Telescope observations revealed the presence of a large body of water-related molecules in orbit about 240,000 kilometers (almost 150,000 miles) from Saturn. Richardson and Jurac modeled this water cloud and demonstrated it could migrate inward to the A-ring. "We relied on their predictions to help us interpret our data," said Farrell. "They predicted it, and we were seeing it."
At the time of their prediction, the source of the water cloud was unknown. The source was not identified until 2005 when Cassini discovered the stunning geysers emitted from Enceladus.
Data for the discovery that Saturn's A-ring acts like a sponge were collected in July 2004 when Cassini arrived in orbit around Saturn, making its closest flyby over the A-ring. "We skimmed over the top of that ring fairly close," said Farrell.
Hot spots on the inside wall of the plasma donut -- the part colliding with the A-ring -- were emitting radio signals. These signals behaved as a sort of natural radio beacon, indicating the local plasma density at the inner edge of the donut. The signals were detected by Cassini's Radio and Plasma Wave instrument. The team used these signals to monitor the density of the plasma (the higher the frequency, the greater the density) and hence witness the change in gas density with time.
"As we approached the A-ring, the frequency dropped, implying that the plasma density was going down because it was being absorbed by the ring," said Farrell. "What really drove this home was what happened to the signal when we passed over a gap in the rings, called the Cassini division. There, the frequency went higher, implying that the plasma density was going up because plasma was leaking through the gap."
The research was funded by NASA through the Cassini-Huygens project. Cassini-Huygens is an international collaboration among NASA, the European Space Agency, and the Italian Space Agency. The Cassini orbiter was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif.  

Are we sending a bit too much information into the cosmos?

Written by Ian O'Neill

On Monday (February 4, 7 pm EST) NASA's Deep Space Network (DSN) sent a transmission toward the North Star, Polaris. The transmission sent was the song "Across the Universe" by the Beatles intended for any sufficiently advanced extra terrestrial life to listen to. Although this is a nice gesture and may nurture Beatles fans beyond our solar system, some scientists have expressed concerns for advertising our planet's location to the universe, just in case the aliens listening in aren't that friendly after all…

Scientists attending the Search for Extra-Terrestrial Intelligence (SETI) "Sound of Silence" meeting at Arizona State University in Tempe this week are worried. Their concern focuses on some aspects of the scientific community who want to advertise and educate sufficiently advanced lifeforms beyond Earth about our presence and location in the cosmos. Previous efforts have included information about our biology on the Voyager and Pioneer probes, and a broadcast by the Arecibo observatory in 1974. These attempts at communication plus accidental "leakage" of TV and radio signals can all travel vast distances through space and perhaps be received by aliens.
The main argument against trying to communicate with other civilizations is the possibility that if there are aliens out there listening in, then perhaps they might not be friendly. By giving away our location, critical facts about our society, biology and intelligence, we have already given possible alien aggressors a strategic advantage. This threat is obviously very far-fetched, but sending information about our current state of humanity will be inaccurate when signals are received in hundreds, thousands or millions of year's time, perhaps putting our future generations in a negative light.

"Before sending out even symbolic messages, we need an open discussion about the potential risks […] It's very charitable to send out our encyclopedia, but that may short-change future generations." - Douglas Vakoch of the SETI Institute, Mountain View, California.

Vakoch is not concerned that we are risking an alien invasion any time soon, but does highlight the need to discuss the implications of attempted extra-terrestrial communication in an open scientific forum before acting.
If there are any advanced alien beings out there however, they are keeping very quiet. The purpose of the "Sound of Silence" meeting is to discuss why the SETI project has, thus far, not found anything compelling to suggest there are any life forms transmitting their presence to the universe.

"Have we been looking in the wrong place, at the wrong time, in the wrong way?" asks Prof Paul Davies of Arizona State University. "The purpose of this meeting is to brainstorm some radically new thinking on the subject."

Source: Telegraph.co.uk

Filed under: NASA, SETI

Extremophile Hunt Begins in Antarctica, Implications for Exobiologists

Written by Ian O'Neill

An expedition has set off for Antarctica's Lake Untersee in the quest to find bacteria living in one of the most extreme environments on Earth. The bacteria-hunting team are looking for a basic lifeform in a highly toxic location. Resembling the chemistry of Mars, moons of Jupiter and Saturn, even comets, the ice-covered lake may hold some clues to how life might survive, thrive even, beyond the "normality" of our planet.

Lake Untersee is a strange place. For starters, it is always covered in ice. Secondly, the water's pH level is so alkali that it resembles bleach rather than regular lake water. And third, it produces methane on a scale that dwarfs any other source on Earth. In fact, the chemistry of this terrestrial location has been likened to the high alkalinity, high methane environments on Mars, frozen moons and comets in our solar system neighborhood.

We already know that extreme life can thrive in the superheated conditions along volcanic vents in the oceans and they can live quite happily in nuclear reactors. Some bacteria are content to be frozen for over 30,000 years before they are thawed to continue life as if nothing had happened. So the search continues… can life thrive in conditions where the pH (a measure of a substances acidity or alkalinity) is considered to be toxic to life? The head scientist of the Antarctic team, Richard Hoover of NASA's Marshall Space Flight Center, believes that although we consider life that we know to thrive in the "normal" conditions we know and experience ourselves, this may not be the "norm" for life elsewhere in the cosmos.

"One thing we've learned in recent years, is that you don't have to have a 'Goldilocks' zone with perfect temperature, a certain pH level, and so forth, for life to thrive." - Richard Hoover.

The team of US, Russian and Austrian scientists hope to identify additional extreme bacteria to add to their impressive accolade of discoveries. So far, previous teams headed by Hoover have found new species and genera of anaerobic microbial extremophiles in the ice and permafrost of Alaska, Siberia, Patagonia, and Antarctica. Now they hope to find life that is hardy enough to deal not only with the extreme cold of the Antarctic, but also with the "normally" poisonous pH and high methane in Lake Untersee. This will characterize the signature of extreme life, a great help to exobiologists when results come in from future life-hunting missions to Mars and other planetary bodies.

"With our research this year, we hope to identify some new limits for life in terms of temperature and pH levels. This will help us decide where to search for life on other planets and how to recognize alien life if we actually find it." - Hoover.

Eyes to the Skies Getting Bigger

February 4, 2008

Associated Press/AP Online

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By SETH BORENSTEIN WASHINGTON - A telescope arms race is taking shape around the world. Astronomers are drawing up plans for the biggest, most powerful instruments ever constructed, capable of peering far deeper into the universe - and further back in time - than ever before.
The building boom, which is expected to play out over the next decade and cost billions of dollars, is being driven by technological advances that afford unprecedented clarity and magnification. Some scientists say it will be much like switching from regular TV to high-definition.
In fact, the super-sized telescopes will yield even finer pictures than the Hubble Space Telescope, which was put in orbit in 1990 and was long considered superior because its view was freed from the distorting effects of Earth's atmosphere. But now, land-based telescopes can correct for such distortion.
Just the names of many of the proposed observatories suggest an arms race: the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope, which was downsized from the OverWhelmingly Large Telescope. Add to those three big ground observatories a new super eye in the sky, NASA's James Webb Space Telescope, scheduled for launch in 2013.
With these proposed giant telescopes, astronomers hope to get the first pictures of planets outside our solar system, watch stars and planets being born, and catch a glimpse of what was happening near the birth of the universe.
"We know almost nothing about the universe in its early stages," said Carnegie Observatories director Wendy Freedman, who chairs the board that is building the Giant Magellan Telescope. "The GMT is going to see in action the first stars, the first galaxies, the first supernovae, the first black holes to form."
When scientists look at a faraway celestial object, they are seeing it as it existed millions and millions of years ago, because it takes so long for light from the object to reach Earth.
Current telescopes are able to look back only about 1 billion years in time. But the new telescopes will be so powerful that they should be able to gaze back to a couple of hundred million years after the Big Bang, which scientists believe happened 13.7 billion years ago. That's where all the action is.
"We hope to answer these questions: Are we alone in the universe? What is the nature of dark matter and dark energy in the universe?" said astronomer Henri Boffin, outreach scientist for the European Southern Observatory.
Two new technologies enable this extraordinary quest - one reliant on modern lasers and computing power and the other inspired by ancient Greek and Roman tilework.
The first is adaptive optics. It allows telescopes on the ground to get rid of the distortion caused when looking through Earth's thick atmosphere into space.
Adaptive optics relies on a laser to create an artificial star, or a constellation of fake stars, in the sky. Astronomers then examine the fake stars and use computers to calculate how much atmospheric distortion there is at any given time. Then they adjust the mirrors to compensate like a pair of eyeglasses. This adjustment happens automatically hundreds of times per second.
Adaptive optics worked first for smaller telescopes. But getting it to work for big observatories was a problem. The first successful use in large telescopes was in 2003 at the twin-telescope Keck Observatory in Hawaii, an effort that took nine years.
The second breakthrough involves technology that makes bigger mirrors possible. Instead of casting a giant mirror in one piece, which is difficult and limits size, astronomers now make smaller mirror segments and piece them together.
Keck scientist Jerry Nelson, now working on the Thirty Meter Telescope, pioneered this technique and said he got the idea from looking at how the Greeks and Romans tiled their baths. This technique is going from 36 segments in current telescopes to 492 segments with his new project.
In astronomy, the bigger the mirror, the greater the amount of light that can be grabbed from the universe. For the past decade and a half, the Keck has had the largest Earth-bound telescopes, with mirrors nearly 33 feet in diameter.
However, three giant land observatories, proposed for construction within the decade, are going to dwarf those:
- The Giant Magellan Telescope. A partnership of six U.S. universities, an Australian college, the Smithsonian Astrophysical Observatory and the Carnegie Institution of Washington will place the telescope in Las Campanas, Chile, around 2016. The plan is for an 80-foot mirror. The cost is around $500 million.
- The Thirty Meter Telescope. The California Institute of Technology, the University of California and the Association of Canadian Universities for Research in Astronomy are aiming for a telescope with about a 98-foot mirror by 2018. No site has been chosen. The cost is about $780 million.
- The European Extremely Large Telescope. A partnership of European countries called the European Southern Observatory already has telescopes in Chile and is aiming for a new one with a mirror of 138 feet, scaled back from initial plans of 328 feet. The Europeans are aiming for a 2018 completion, but have not chosen a specific location yet. The cost would be $1.17 billion.
The managers of these projects are fairly confident they will get the money they need to complete their grand visions. However, some astronomers worry that there may not be enough private or government money for all of them, so they find themselves competing for funding, even as they cheer each other on.
If completed, ESO's European Extremely Large Telescope would be the biggest of the new observatories and should be able to see 20 to 100 times more sharply than the current best land-based telescopes. The Hubble, which set the standard for stunning astronomical pictures, will seem less amazing.
"Oh, you ain't seen nothing yet," said 2006 Nobel Prize-winning physicist John Mather, senior project scientist for NASA's James Webb Space Telescope.
The $4.5 billion Webb Telescope, designed to travel 900,000 miles beyond Earth's orbit, is not faced with the atmospheric distortion of ground telescopes. Still, it will use its own version of adaptive optics. Because of temperature fluctuations in the cold of space, the telescope will have to adjust the shape of its mirrors automatically. Webb's mirror, which is 2 1/2 times bigger than Hubble's, has 18 segments.
While places like Arizona and Hawaii have been successful sites for high-quality space images, Chile is the focal point of the next-generation building boom.
Both the Thirty Meter and European telescope are looking at several sites there although the Thirty Meter team is also considering Baja Mexico and Hawaii. What's needed is the right combination of atmospheric conditions, weather, high altitude, prevailing winds and dark skies.
But there is more in the works than just the super-sized scopes. Smaller, more specialized telescopes are in various stages of design and construction.
The $400 million Large Synoptic Survey Telescope to be built in Chile by 2014 would survey the sky, constantly shooting a movie of 20 billion objects in the cosmos and spotting targets for bigger telescopes.
A planned project in Hawaii would be on the lookout for "killer asteroids." And in Chile, dozens of high-precision antennas are being erected for a huge radio astronomy observatory, called ALMA, that would look into the universe in a different way.
It is the biggest observatories in the works, however, that will provide the dramatic change in astronomical pictures. The pictures to come, Nelson said of the Thirty Meter project, will "knock your socks off, faint stuff that Hubble can't see."
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On the Net:
Thirty Meter Telescope: http://www.tmt.org  
Giant Magellan Telescope: http://www.gmto.or  
European Extremely Large Telescope:
http://www.eso.org/public/astronomy/projects/e-elt.html  
James Webb Space Telescope: http://www.jwst.nasa.gov
A service of YellowBrix, Inc.

NASA Wants You!

Now's your chance for celestial immortality — sort of. NASA wants you to put on your thinking caps and come up with a name for the Gamma-ray Large Area Space Telescope (GLAST), a high-energy telescope scheduled for launch in mid-May.

NASA's Gamma-ray Large Area Space Telescope (GLAST) will scan the sky for high-energy photons. But the space agency is looking for a new name. Submit your best here.

NASA / GSFC

For five to ten years, GLAST will scan the universe, collecting and analyzing the most powerful photons coming from objects ranging from the Sun to distant galaxies.

Mission planners are opening the floor to the public to get them involved in the mission. "The idea is to give people a chance to come up with a name that will fully engage the public in the GLAST mission," says project scientist Steve Ritz (NASA/Goddard Space Flight Center) in the announcement released today.

To submit your idea, read the guidelines at the GLAST website and fill out the form. Entries are due by the end of March. Be sure to print out your own "certificate of participation" so you'll be able to prove to your friends that you came up with the selected name.

Posted by Stuart Goldman, February 7, 2008

Um mistério e tanto!

Postado por Cássio Barbosa em 07 de Fevereiro de 2008 às 18:21

O que você está vendo não tem explicação. Ao menos uma definitiva. Essa imagem mostra a galáxia elíptica NGC 1132. A imagem em si é uma composição de imagens do telescópios espaciais Hubble e Chandra. A "névoa" rosada representa a emissão de raios X (obtida pelo Chandra) dessa galáxia elíptica. A própria galáxia parece uma mancha difusa, rodeada por diversas outras galáxias anãs e outras que estão na verdade ao fundo, sem conexão física com esse grupo em primeiro plano.
Mas qual é o mistério de NGC 1132? Dados recentes do Chandra mostraram que essa galáxia elíptica possui muita matéria escura. Mas muito mesmo! A quantidade desse tipo misterioso de matéria ao redor dessa galáxia é comparável à quantidade de matéria escura encontrada normalmente em grupos inteiros de galáxias! A emissão de raios X de NGC 1132 também é comparável à de um grupo inteiro de galáxias.
Esse tipo de galáxia forma o que se chama de grupo fóssil, pela sua gigantesca quantidade de matéria escura. Sua origem ainda permanece um mistério, mas duas hipóteses competem entre si. A primeira delas diz que essas galáxias elípticas gigantescas são na verdade o resultado da fusão de várias outras galáxias que formavam um grupo normal de galáxias no passado. A segunda hipótese diz que esse é um tipo muito especial de galáxia, formado em uma região ou em um período de tempo que em as condições inibiam de alguma maneira a formação de galáxias de tamanho médio. Ninguém ainda tem certeza sobre a hipótese correta, mesmo porque cada uma delas tem uma profunda relação com a própria formação do Universo.
O fato é que galáxias elípticas como estas podem conter trilhões de estrelas, mas como possuem uma grande quantidade de gás quente (responsável pela emissão dos raios X) não podem formar novas estrelas. NGC 1132 está a 320 milhões de anos-luz de distância, na constelação de Erídano.

Nasa adia caminhada espacial para instalação de laboratório europeu na ISS

 

Publicada em 10/02/2008 às 15h26m

EFE e CNN
WASHINGTON - A Nasa adiou para esta segunda-feira a instalação do laboratório europeu Columbus na Estação Espacial Internacional (ISS, na sigla em inglês), devido a um problema de saúde de um dos astronautas. O ônibus espacial Atlantis se acoplou, no sábado, à ISS , pondo fim a uma viagem de dois dias. Estava previsto que o astronauta alemão Hans Schlegel participasse da caminhada, mas ele será substituído pelo americano Stan Love, informou a agência espacial americana. (Veja imagens da chegada da Atlantis)
A Nasa não explicou o motivo da substituição, mas o comandante da Atlantis, Stephen Frick, solicitou atendimento médico médica privado após chegar a estação espacial. É comum astronautas sentirem enjôo ou outros problemas depois de serem lançados ao espaço.

" Não vai afetar nenhum dos objetivos desta missão "

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- Direi apenas que não vai afetar nenhum dos objetivos desta missão - afirmou John Shannon, presidente da equipe de controle da missão, acrescentando que o incidente obrigará apenas a reorganização de algumas atividades.
Shannon evitou dar mais detalhes, ao citar a privacidade médica, mas destacou que não se trata de uma condição que ponha em perigo a vida do astronauta.
Schlegel, de 56 anos, que foi à ISS na Atlantis, não parecia estar doente durante as imagens nas quais aparecia flutuando na ISS. Estava previsto que o astronauta participasse da primeira de três caminhadas com o americano Rex Walheim. A segunda caminhada está prevista para quarta-feira.
O encontro das duas naves a quase 400 quilômetros da superfície terrestre aconteceu sem problemas, informou o controle da missão no centro espacial Kennedy, na Flórida. O laboratório está avaliado em US$ 1,9 bilhão.

X-rays betray giant particle accelerator in the sky

EUROPEAN SPACE AGENCY NEWS RELEASE
Posted: February 2, 2008

ESA's orbiting gamma-ray observatory, Integral, has made the first unambiguous discovery of highly energetic X-rays coming from a galaxy cluster. The find has shown the cluster to be a giant particle accelerator.  
The Ophiuchus galaxy cluster is one of brightest in the sky at X-ray wavelengths. The X-rays detected are too energetic to originate from quiescent hot gas inside the cluster and suggest instead that giant shockwaves must be rippling through the gas. This has turned the galaxy cluster into a giant particle accelerator.
Most of the X-rays come from hot gas in the cluster, which in the case of Ophiuchus is extremely hot, at 100 million degrees Kelvin. Four years ago, data from the Italian/ Dutch BeppoSAX satellite showed a possible extra component of high-energy X-rays in a different cluster, the Coma cluster.
"Two groups analysed the data. One group saw the component but the other did not," says Dominique Eckert, Integral Science Data Centre (ISDC), University of Geneva, Switzerland. So Eckert and colleagues from ISDC launched an investigation into the mystery.
They turned to Integral and its five-year, all-sky survey and found that ESA's orbiting gamma-ray observatory did show an unambiguous detection of highly energetic X-rays, coming from the Ophiuchus cluster of galaxies. These X-rays can be produced in two ways, both of which involve high-energy electrons.
The first option is that the electrons are caught in the magnetic field threading through the cluster. In this case, the electrons would spiral around the magnetic field lines, releasing synchrotron radiation in the form of X-rays.
The electrons would be extremely energetic, carrying over 100 000 times the energy of the electrons in the alternative scenario, which is that the electrons are perhaps colliding with microwaves left over from the origin of the Universe and now bathe all of space. In such collisions, the electrons lose some energy, emitted as X-rays.
Determining which of these scenarios is correct is the next job for the team. They plan to use radio telescopes to measure the magnetic field of the galaxy cluster. They also plan to use the High Energy Stereoscopic System (HESS) in Namibia. This giant telescope looks for the brief flash of light generated when highly energetic gamma rays collide with particles in Earth's atmosphere. If HESS sees such flashes coming from Ophiuchus, then the astronomers will know that the synchrotron scenario is correct.
Either way, the electrons themselves are most likely to be accelerated to high energies by shockwaves travelling through the cluster gas. The shockwaves are set up when two clusters collide and merge. The question is how recently Ophiuchus swallowed its companion cluster.
In the synchrotron scenario, the highly energetic electrons cool very quickly. If the team find this to be the case, then the collision must still be in progress. In the case of microwave scattering, cooling takes a long time and the collision could have taken place at any time in the past.
Once the scientists know, they will be able to properly understand the history of the cluster. One thing is already certain; nature has transformed the galaxy cluster into a powerful particle accelerator, perhaps 20 times more powerful than CERN's Large Hadron Collider (LHC), which begins operation in Switzerland this summer.
"Of course the Ophiuchus cluster is somewhat bigger," says Stephane Paltani, a member of the ISDC team. While LHC is 27 km across, the Ophiuchus galaxy cluster is over two million light-years in diameter."  

Canadians Fight for Observatory

 

Despite the plans of the University of Toronto to close David Dunlap Observatory (DDO) and sell the land, plenty of people aren't happy about it.

We learned this week that there is an online petition that calls for the university to call off the sale. I've wondered about Internet petitions. Do they actually work? The one for the DDO has more than 1,600 signatures, but a bunch of them are noted as "anonymous." I find it rather odd to sign a petition and keep it to yourself. I understand that the person's real name is logged in the system and simply not displayed on the website, but it's still curious.

David Dunlap Observatory, with it's 74-inch (1.9-meter) reflector, is set to be sold in mid-February.

David Dunlap Observatory

The e-mail I received about the petition says that all the names will be printed and taken to the provincial legislature and the university.

Toronto's National Post newspaper has had several articles about the controversy, including how teenagers are trying to save the observatory.

Perhaps equally significant is the story angle about how institutions who receive donations of land and/or money sometimes don't do what they are supposed to do with the bequest. A follow-up article last week explains that a court battle resolved in the university's favor invalidated a clause that said: "should the lands cease to be used for an observatory" it shall "revert to . . . her heirs." This allowed the university to legally sell the property, which is set to close in mid-February.

Changing the rules of a donation sets a bad precedent. Although it probably will never happen, I still occasionally think about winning a lot of money and donating some of it somewhere, perhaps to have an observatory named after me. (Bill Gates donated $10 million to help fund the Large Synoptic Survey Telescope — but he earned his money.) It's sad to think that future lawyers could strip me of the legacy.

Posted by Stuart Goldman, January 17, 2008

Eclipse Total da Lua: 20/21 de Fevereiro de 2008

 

Prezados amigos

 

Já se encontram disponíveis no site URANOMETRIA NOVA as informações sobre o ECLIPSE TOTAL DA LUA de 20/21 de fevereiro de 2008:

 

ECLIPSE TOTAL DA LUA 20/21 DE FEVEREIRO DE 2008
http://www.uranometrianova.pro.br/circulares/circ0032.htm

 

 

Destacam-se ainda:

 

FENÔMENOS ASTRONÔMICOS:
http://www.uranometrianova.pro.br/calenda/2008/02/fen0208.htm

CALENDÁRIO ASTRONÔMICO:
http://www.uranometrianova.pro.br/calenda/2008/02/cal0208.htm

DEUSES E PLANETAS
http://www.uranometrianova.pro.br/historia/Mitos/deuses/deuses.htm

PROF. RUBENS DE AZEVEDO
http://www.uranometrianova.pro.br/historia/hda/0005/razevedo.htm

URANOMETRIA NOVA (Página Inicial)
http://www.uranometrianova.pro.br/

 

 

Saudações

 

Irineu Gomes Varella
Priscila Di Cianni Ferraz de Oliveira

.

__,_._,___

RedLIADA No. 405: ¿Sabías qué? con los Hitos de Galileo Galilei

InfoLIADA-Observe-LaNoticia-AstroNoticias
AstroNáutica- Efemérides

Lea al final...¿Sabías que...?
__________________________________________

"Semper Observandum"

RedLIADA - La Red de Observadores
Liga Iberoamericana de Astronomía

Edición Electrónica No. 405 - Domingo 10 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
http://www.tayabeixo.org y http://www.liada.net

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

ASOCIESE a la LIADA. Informese en
http://www.liada.net/afilia.htm

*******************************************

InfoLIADA

 

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:

 

http://sunearth.gsfc.nasa.gov/eclipse/LEmono/TLE2008Feb21/TLE2008Feb21.html

 

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
incluirmos em nossos relatórios de projetos de ensino e divulgação.

POR FAVOR, COMUNIQUEM-NOS SEUS RESULTADOS.

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

bretones@mpc.com.br

Seção de Ensino e Divulgação de Astronomia 

SEDA-LIADA

 

*******************************************

 

 OBSERVE ESTA SEMANA…

 

A SIMPLE VISTA:

*El miércoles 13, la Luna en Cuarto Creciente.                   

*El viernes 15, en la noche, la conjunción de la Luna con la estrella El-Nath.

*El sábado 16, en la madrugada, la conjunción de Marte con la Luna.

 

CON BINOCULARES:

*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 Pisces (8m,5).

*El cometa C/2007 T1 (McNaught), en la constelación de Mensa (9m,0).

 

CON TELESCOPIOS:

*El lunes 11, en la madrugada, el tránsito de la Gran Mancha Roja de Júpiter.

*El viernes 15, en la madrugada, el tránsito de Ganímedes a través del disco de Júpiter.

*El sábado 16, en la madrugada, el tránsito de la Gran Mancha Roja de Júpiter.

 

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LA NOTICIA DE LA SEMANA.

PROBLEMA MÉDICO RETARDA INSTALACIÓN DE MÓDULO "COLUMBUS".  

09 de febrero de 2008. 

Un problema médico con un miembro de la tripulación del transbordador espacial ha forzado un cambio en el personal para las primeras caminatas espaciales fijadas en la misión STS-122 para la instalación del módulo científico "Columbus" (Colón), de la Agencia Espacial Europea. El inicio del montaje, previsto para el día domingo, se trasladó hasta el lunes 11 y el astronauta Stan Love ha sido reemplazado por Hans Schlegel, en la caminata inicial.

Más información en:

http://www.nasa.gov/mission_pages/shuttle/main/index.html

http://www.universetoday.com/2008/02/09/medical-problem-delays-spacewalk/

http://spaceflightnow.com/shuttle/sts122/080209fd3/index5.html

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ASTRONOTICIAS.

UNA ESTRELLA SE COME A OTRA Y HACE PLANETAS DE LAS MIGAS

08 de febrero de 2008.

Una estrella inusual puede haberse tragado a su compañera estelar y ahora eructa una nube formadora de planetas como resultado, según reporta un nuevo estudio.

La estrella, llamada BP Piscium, está rodeada de un denso disco de gas y polvo cósmico desde el cual parece estar succionando material a una velocidad prodigiosa. 

Estas propiedades son típicas en estrellas jóvenes, pero BP Piscium parece ser mucho más vieja, basándose en los débiles signos de litio en el espectro de su luz. Las estrellas más jóvenes tienen suficiente litio pero éste se va destruyendo en la medida que la estrella envejece.

Más información en:

http://space.newscientist.com/article/dn13296-star-eats-star-and-builds-planets-from-the-crumbs.html?feedId=online-news_rss20

EL FINAL DE LA TIERRRA, SEGÚN LOS ASTRÓNOMOS.

25 de enero de 2008.

Los astrónomos saben que estrellas como nuestro Sol evolucionan a través de distintas etapas: gigante roja, nebulosa planetaria y luego enana blanca. Astrónomos de México y Gran Bretaña se han dedicado al estudio detallado de ese futuro, usando modelos estelares que incluyen códigos de evolución ya verificados. Por ejemplo, en el estadio de gigante roja, dentro de 7,5 millardos de años, se estima que el Sol reducirá su masa a dos tercios de la actual, expandiendo y expulsando lentamente el tercio restante, a medida que crece como gigante. Esta circunstancia implicará que la órbita de la Tierra se expandirá 1,5 veces su tamaño actual, pero a pesar de esto no podrá huir de la fase expansiva del Sol: la Tierra sufrirá mareas gravitacionales y será "arrastrada" por la cromosfera solar, siendo engullida por el Sol.

Los restantes planetas podrían sobrevivir esta fase porque están más lejos. Además, los astrónomos predicen que nuestro Sol no pasará por la etapa de nebulosa planetaria, ya que habrá perdido casi todas sus capas externas en la fase de de gigante roja, pero consideran que el pulso térmico puede producir una cáscara circumestelar de pequeño tamaño, como en la pequeña nebulosa planetaria PN IC 2149. Esta cáscara contendría apenas varios centésimos de la actual masa solar.

Más información en:

http://arxiv.org/abs/0801.4031

CORRIENTES DE HIDRÓGENO CONECTAN LA VÍA LÁCTEA CON LAS NUBES DE MAGALLANES.

05 de febrero de 2008.

Radioastrónomos han descubierto que las Nubes de Magallanes, dos galaxias enanas cercanas a la Vía Láctea y observables en el hemisferio Sur celeste, se encuentran unidas con ésta a través de una corriente de gas hidrógeno. El extremo de este arroyo de gas, denominado por los astrónomos como Nubes de Alta Velocidad (HVC), hace contacto con nuestra galaxia en un punto de la constelación de Cruz del Sur, a unos 70.000 años-luz de nosotros. La nube se denomina HVC306-2+230 y le servirá a los astrónomos para medir la velocidad de estas galaxias enanas. Anteriormente, los astrónomos pensaban que las Nubes de Magallanes eran satélites que giraban en torno a la Vía Láctea, pero nuevas observaciones realizadas con el telescopio espacial Hubble han mostrado que se mueven más rápido de lo que se pensaba, pudiendo entonces, estar de paso por las cercanías de nuestra galaxia.

Más información en:

http://www.csiro.au/news/GasFinger.html

http://www.universetoday.com/2008/02/05/stream-of-hydrogen-connects-the-milky-way-and-the-magellanic-clouds/

MATERIA OSCURA Y ENERGÍA OSCURA ¿LA MISMA COSA? 

06 de febrero de 2008.  

Lo hemos expresado en varias ocasiones: la materia regular en el Universo constituye sólo el 4% de lo existente. El otro 96% pertenece a la materia y a la energía oscura.  

Dr. HongSheng Zhao, de la escuela de Física y Astronomía de la Universidad de St Andrews, ha desarrollado un modelo que muestra cómo se unen la materia y la energía oscura, más de lo que anteriormente se pensaba. 

El Dr. Zhao señala que la materia oscura y la energía oscura podrían ser las dos caras de una misma moneda. "Cuando en el futuro, los astrónomos comprendan los efectos sutiles de la energía oscura en las galaxias, al mismo tiempo, estará resolviendo el misterio de materia oscura". 

La materia oscura fue propuesta de manera teórica en 1933, por el astrónomo suizo Fritz Zwicky, cuando notó que las galaxias no podrían mantenerse unidas con el sólo concurso de la materia observable.  

La energía oscura fue prevista a finales de la década de los 90 del siglo pasado, durante un estudio de supernovas distante. En lugar de encontrar evidencias que la gravedad mutua de todos los objetos en el Universo estaba reduciendo su velocidad de expansión, los investigadores descubrieron que su expansión se estaba acelerando.  

Más información en:

http://www.st-andrews.ac.uk/news/Title,18940,en.html

http://www.universetoday.com/2008/02/06/dark-matter-and-dark-energy-the-same-thing/

INVESTIGADORES EXPLICAN LAS PLUMAS HELADAS EN ENCELADO.  

06 de febrero de 2008.  

Desde que la sonda espacial Cassini descubrió los jets de hielo eyectados desde la luna Encelado, de Saturno, los científicos han estado tratando de explicar el fenómeno físico. La luna es muy fría y se encuentra muy lejos del Sol para ser calentada por éste. En la actualidad se ha descubierto que los jets emanan desde el polo Sur de la luna, en unas hendiduras similares a las rayas de un tigre. Un equipo de investigadores alemanes de la Universidad de Potsdam, conducidos por Juergen Schmidt, ha desarrollado a un modelo de computadora que describe lo que ocurre en el fondo de estas ranuras: el vapor de agua y los granos de hielo son expelidos a través de fisuras en forma de embudos. Los granos más pesados impactan contra los lados del agujero y disminuyen su velocidad. Esto explica por qué las partículas de hielo salen a menores velocidades que el vapor de agua. El interior de Encelado se calienta producto del efecto de la marea gravitatoria, similar al que ocurre en la luna Io, de Júpiter. La superficie de Encelado se encuentra a -193 °C, mientras que las fisuras están a -133 °C. Esto significa que el interior de la luna debe ser aun más caluroso. 

Más información en:

http://www.nature.com/nature/journal/v451/n7179/full/nature06491.html

http://www.universetoday.com/2008/02/06/researchers-explain-enceladus-icy-plume/

EXOBIÓLOGOS INICIAN CAZA DE BACTERIA EXTREMÓFILA.  

08 de febrero de 2008. 

Una expedición se ha trasladado al lago antártico de Untersee con la finalidad de encontrar bacterias que viven en uno de los ambientes más extremos en la Tierra. El equipo de caza-bacterias está buscando una forma de vida básica en una situación muy tóxica. Pareciéndose a la química de Marte, las lunas de Júpiter y Saturno e incluso a los cometas, el lago cubierto de hielo puede arrojar algunas pistas de cómo la vida podría sobrevivir, e incluso crecer, más allá de la "normalidad" de nuestro planeta.

Más información en:

http://www.physorg.com/news121697053.html

http://www.universetoday.com/2008/02/08/extremophile-hunt-begins-in-antarctica-implications-for-exobiologists/

RAYOS X DEVELAN GIGANTESCO ACELERADOR CÓSMICO DE PARTÍCULAS.  

02 de febrero de 2008. 

El observatorio orbital de rayos X de la Agencia Espacial Europea, ESA, ha realizado el primer descubrimiento de rayos X muy energéticos, que provienen de un cúmulo de galaxias. El hallazgo ha mostrado que el cúmulo funciona como un gigantesco acelerador de partículas. El cúmulo de galaxias de Ofiuco (Ophiuchus) es uno de más luminoso en el cielo, en las longitudes de onda de rayos X. Estos rayos son demasiado energéticos, como para haber sido originados por el gas caliente entre las galaxias y sugiere la idea que gigantes ondas de choque están ondeando a través del gas, circunstancia que convierte al cúmulo galáctico en un acelerador de partículas.  

La mayoría de los rayos X que provienen del gas en el cúmulo de Ofiuco, están sumamente calientes, alrededor de 100 millones de grados Kelvin. Hace cuatro años, los datos aportados por el satélite italiano-holandés, el BeppoSAX, permitió descubrir un componente altamente energético en los rayos X que provienen del cúmulo galáctico de Coma Berenices. 

Más información en:

http://spaceflightnow.com/news/n0802/02integral/

 

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ASTRONÁUTICA.

PROBANDO UNA SONDA PROTOTIPO PARA LA LUNA EUROPA.  

09 de febrero de 2008. 

Mientras que la NASA no tiene ningún plan definido para enviar una sonda espacial a la luna Europa, de Júpiter, muchos científicos planetarios consideran que la exploración de la misma es de una alta prioridad. Las evidencias recolectadas por las sondas espaciales Voyager y Galileo, sugieren la existencia de un inmenso océano de agua salada debajo de la cáscara helada de Europa. Sin embargo, la NASA está colaborando con la Universidad de Wisconsin para consolidar un vehículo submarino a ser usado en los lagos cubiertos de hielo en la Tierra y evaluar la operatividad del mismo en un ambiente similar al que existe en la luna joviana. Las próximas pruebas del vehículo tendrán lugar entre los días 12-15 de febrero en el Lago Mendota, Madison.

Más información en:

http://www.nasa.gov/home/hqnews/2008/feb/HQ_M08025_Endurance.html

http://www.universetoday.com/2008/02/09/testing-a-europa-probe-prototype/

BAUTIZA UN SATÉLITE.

07 de febrero de 2008.

¿Qué nombre darle a esta misión espacial? La NASA ha anunciado que tiene pensado solicitarle al público para renombrar la misión GLAST (Gamma-ray Large Area Space Telescope – Telescopio Espacial de Amplio Campo para Rayos Gamma). El satélite será lanzado a mediados del 2008.

Más información en:

http://www.universetoday.com/2008/02/07/name-that-satellite/

http://www.nasa.gov/home/hqnews/2008/feb/HQ_08036_GLAST.html

SONDA DEEP IMPACT INICIA BÚSQUEDA DE PLANETAS EXTRASOLARES.

07 de febrero de 2008.

Culminada su misión primaria en Julio del 2005, la sonda espacial Deep Impact, ha reiniciado una segunda fase de operaciones, ahora ayudando a los científicos en la búsqueda de planetas en torno a otras estrellas.

Más información en:

http://www.universetoday.com/2008/02/07/deep-impact-begins-searching-for-extrasolar-planets/

"KIZUNA" MOVIDO AL EDIFICIO DE ENSAMBLAJE.

06 de febrero de 2008.

El pasado martes 5 de febrero, el satélite para transmisiones de Internet a súper alta velocidad, KIZUNA (Winds) fue transferido al edificio de ensamblaje, para ser cargado al cohete H-IIA y disponerlo para el lanzamiento, el próximo viernes 15 de febrero.

El lanzamiento se efectuará desde el Centro Espacial de Tanegashima y se tiene previsto para las 4.00 p.m. hora local de Japón.

Más información en:

http://www.jaxa.jp/topics/2008/02_e.html

 

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EFEMERIDES

LOS PLANETAS DURANTE LA SEMANA.

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

Venus:

Se observa en las madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Sagitario. Su salida ocurre a las 5:08 HLV (9:38 UT).

Marte:

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 3:05 HLV (7:35 UT).

Júpiter:

Se observa en las madrugadas, hacia el cielo del Este. Se encuentra en la constelación de Sagitario. Su Salida ocurre a las 4:17 HLV (8:47 UT).

Saturno:

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 19:34 HLV (0:04 UT).

EVENTOS DE LA SEMANA

(Del 11 al 17 de febrero de 2008)

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

Lunes 11

11 – Meridiano Central de Marte, 0 UT; 148,7º

11 – Ocultación de Io. Reaparece 9:59,0 UT.

11 – Puesta de la Luna. 22:21 HLV.

11 – Tránsito de la Gran Mancha Roja de Júpiter; 5:15 HLV.

11 - 11 aniversario (1997) del lanzamiento de la misión STS-82 del transbordador Discovery (segunda misión de mantenimiento al telescopio espacial Hubble).

11 - 38 aniversario (1970) del lanzamiento del satélite Ohsumi (primer satélite japonés).

11 – 97 aniversario (1911) del nacimiento de Carl Seyfert, astrónomo estadounidense que desarrolló estudio sobre galaxias con núcleos activos.

11 – 161 aniversario (1847) del nacimiento de Thomas Alba Edison, inventor Estadounidense.

Martes 12

12 – Meridiano Central de Júpiter, Sistema II, 0 UT; 275,3º

12 – Puesta de la Luna. 23:18 HLV.

12 – 7 aniversario (2001) del aterrizaje de la sonda NEAR-Shoemaker en el asteroide Eros.

12 – 34 aniversario (1974) de la inserción en órbita de Marte de la sonda Mars 5.

12 – 47 aniversario (1961) del lanzamiento de la sonda Venera 1 a Venus. Primera sonda interplanetaria de la Unión Soviética.

12 - 61 aniversario (1947) de la caída del meteorite Sikhote Alin (Rusia).

12 – 199 aniversario (1809) del nacimiento de Charles Darwin, naturista inglés desarrollador de la Teoría de la Evolución.

Miércoles 13

13 – Luna en Cuarto Creciente. 23:04 HLV (3:34 UT).                 

13 – Luna en Perigeo (370.224 Kms). 19:30 HLV (0 UT).               

13 – Meridiano Central de Marte, 0 UT; 130,3º

13 – 156 aniversario (1852) del nacimiento de John Dreyer, astrónomo danés, desarrollador del Nuevo Catálogo General (NGC) y del Índice de Catálogo (IC) de objetos extendidos, publicados en 1878 y 1908.

13 – 375 aniversario (1633) del arribo de Galileo Galilei a Roma antes del juicio de la Inquisición.

Jueves 14

14 - El cometa C/2007 T1 (McNaught) en máximo acercamiento a la Tierra (1,063 AU).

14 – Meridiano Central de Júpiter, Sistema II, 0 UT; 215,5º

14 – Puesta de la Luna. 00:18 HLV.

14 - 8 aniversario (2000) de la inserción en órbita del asteroide Eros de la sonda espacial NEAR.

14 – 19 aniversario (1989) del lanzamiento del primer satélite para posicionamiento global, el Block-II.

14 - 36 aniversario (1972) del lanzamiento del Luna 20, misión soviética para retornar muestras lunares a la Tierra.

14 - 45 aniversario (1963) del lanzamiento del Syncom 1, primer satélite de órbita geosincrónica. 14 – 110 aniversario (1898) del nacimiento de Fritz Zwicky, astrónomo búlgaro, nacionalizado suizo, que propuso las Supernovas para medir el Universo y previó la existencia de la materia oscura.  

14 – 112 aniversario (1896) del nacimiento de Edward Arthur Milne, matemático inglés que trabajó sobre las atmósferas estelares.

14 – 160 aniversario (1848) de Benjamín Baillaud, astrónomo francés especialista en mecánica celeste que estudió los movimientos de los satélites de Saturno. Hay un cráter en la Luna con su nombre y el asteroide (11764) Benbaillaud se bautizo en su honor.

Viernes 15

15 – Inicio del Día Juliano 2.454.511,5

15 – Conjunción de la Luna con la estrella El-Nath. 23:00 HLV (3:30 UT).

15 – Lanzamiento del satélite Winds en el cohete japonés H-2A.

15 – Meridiano Central de Marte, 0 UT; 111,7º

15 – Puesta de la Luna. 01:21 HLV.

15 – Puesta de Marte. 2:33 HLV.

15 – Salida de Júpiter. 3:41 HLV.

15 – Salida de Mercurio. 5:23 HLV.

15 – Salida de Saturno. 18:53 HLV.

15 – Salida de Venus. 4:39 HLV.

15 – Tránsito de Ganímedes. Egreso 9:40,7 UT.

15 - 16 aniversario (1992) del sobre vuelo a la Luna de la sonda espacial Hiten.

15 – 73 aniversario (1935) del nacimiento de Roger Chaffee, astronauta estadounidense fallecido con Virgil Grissom y Edward White en el incendio de la capsula Apolo 1 (1967).

15 – 147 aniversario (1861) del nacimiento de Charles Édouard Guillaume, físico suizo-francés, premio Nobel en 1920, que determinó la temperatura correcta del espacio.

15 – 444 aniversario (1564) del nacimiento de Galileo Galilei, científico italiano, padre de la astronomía moderna.

Sábado  16

16 – Marte 1,5º al Sur de la Luna. 3:30 HLV (8 UT).

16 – Meridiano Central de Júpiter, Sistema II, 0 UT; 155,8º

16 – Tránsito de la Gran Mancha Roja de Júpiter; 4:25 HLV.

16 – 47 aniversario (1961) del lanzamiento del Explorer 9 (S-56a). Misión estadounidense para medir la densidad atmosférica.

16 - 60 aniversario (1948) del descubrimiento de la luna Miranda (Urano) por Gerard Kuiper. 

16 – 102 aniversario (1906) del descubrimiento del asteroide 585 Bilkis por August Kopff.

16 – 102 aniversario (1906) del descubrimiento del asteroide 602 Marianna, 603 Timandra y 604 Tekmessa por Joel Metcalf. 

16 – 494 aniversario (1514) del nacimiento de Georges Joachim (Rheticus), astrónomo alemán impulsador de la Teoría heliocéntrica de Copérnico.

Domingo 17

17 – 12 aniversario (1996) de la nave espacial NEAR para orbitar el asteroide Eros.

17 - 43 aniversario (1965) del lanzamiento de la nave Ranger 8 (misión para impactar la Luna).

17 – 285 aniversario (1723) del nacimiento de Tobias Mayer, matemático alemán que descubrió el método de medir la Longitud terrestre a partir de la posición de la Luna. También descubrió la Libración lunar.

17 – 408 aniversario (1600) de la quema en la hoguera de Giordano Bruno por sus concepciones cosmológicas (Campo de' Fiori, Roma).

17 - El cometa 46P/Wirtanen en máximo acercamiento a la Tierra (0,918 AU).

17 – Meridiano Central de Marte, 0 UT;  93,1º

 

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¿SABÍAS QUÉ?

HITOS EN LA VIDA DE GALILEO GALILEI.

Con motivo de celebrarse el próximo viernes 15 de febrero los 444 años del nacimiento del célebre científico italiano Galileo Galilei, nos permitimos recordar algunos hitos de su vida:

 

*1564, febrero 15: Nace Galileo en Pisa. Primogénito del músico florentino Vincenzo Galilei y de Giulia Venturi de los Ammannati de Pescia.

*1581: A los 17 años, se inscribe en el Estudio de Pisa, para seguir estudios de medicina, donde profundiza en la doctrina aristotélica.

*1582: Observa la "oscilación regular" de una lámpara en la catedral de Pisa e intuye que un péndulo puede usarse para llevar control del tiempo.

*1584: Deja la medicina y comienza sus estudios de matemáticas con Ostilio Ricci da Fermo.

*1585: A los 21 años escribe: «Theoremata circa centrum gravitatis solidorum», producto de su indagación sobre los trabajos de Arquímedes.

*1586: Publica: «La bilancetta», ensayo sobre la balanza hidrostática que lo da a conocer en los núcleos académicos de la época.

*1589: Publica «Consideraciones sobre Tasso», y los manuscritos «De motu» en franca crítica a Aristóteles, explicando de modo ingenioso la caída de los cuerpos y la curva parabólica que describen los proyectiles.

*1592: Obtiene la cátedra de matemáticas de Padua donde laborará por 18 años.

*1597: Escribe el texto para sus clases: «Tratado de la esfera o Cosmografía». Convencido sobre la validez de la teoría heliocéntrica de Nicolás Copérnico, se lo manifiesta en una carta Johannes Kepler, quien le había enviado una copia de su "Prodomus dissertationum cosmographicarum".

*1604: Dicta una serie de lecciones: "Sopra una nuova stella". Es confirmado en su cargo como enseñante en la Universidad de Padua.

*1607: Construye un  termoscopio neumático, prototipo del termómetro que diseñaría su discípulo Evangelista Torricelli años después usando mercurio.

*1609: Interesado por los trabajos de óptica del ambiente artesanal holandés, fabrica su propio anteojo. Lo dirige hacia el cielo y realiza los primeros descubrimientos astronómicos de la era instrumental: el cielo poblado de innumerables objetos celestes, nuevas estrellas, la estructura real de la Vía Láctea, las fases del planeta Venus, la estructura triple de Saturno (la resolución de su pequeño telescopio no le permitió ver que se trataba de un anillo que lo rodeaba), lo accidentado del paisaje lunar; todo lo cual, hace tambalear el dogma de "perfección" en las alturas que prevalecía oficialmente desde Ptolomeo.

*1610, enero 7: observa tres "stellas" alineadas junto a Júpiter, dos a la derecha y una a la izquierda. La noche siguiente las ve de nuevo pero en diferente posición, todas del lado occidental. El día 10, dos están al oriente y una como oculta por el planeta. El día 12, luego de dos horas de observación, asiste a la desaparición de la tercera estrella y el 13 aparecen cuatro "estrellas". Son las lunas de Júpiter que llamó "Sidera Medicea" en honor de Cosme II de Médicis, quien el 10 de julio lo nombra "Primer Matemático y Filósofo del Gran Duque de Toscana".

*1611: Se publica: «Sidereus Nuncius», obra donde expone sus descubrimientos.

*1612: Publica el «Discurso en torno a las cosas que están sobre el agua».

*1613: Publica «Historia y demostraciones en torno a las manchas solares y sus accidentes», donde sostiene expresamente la teoría copernicana.

*1615: El padre dominico Niccolo Lorini denuncia a Galileo ante el tribunal de la Inquisición.

*1616: El Santo Oficio incluye en el "Índice de libros prohibidos" el "De rebolutionibus" de Copérnico y prohíbe a Galileo volver a mencionar la teoría copernicana.

*1618: Aparición de 3 cometas en la constelación de Scorpio.  Se reintroduce la cuestión copernicana.

*1623: Se imprime en Roma su obra: «Il Saggiatore», tal vez su libro más controversial, por la agria discusión sobre la naturaleza de los cometas con el jesuita Orazzo Grassi.

*1632: En febrero se publican en Florencia los primeros ejemplares del «Diálogo sobre los dos máximos sistemas del mundo», pero son secuestrados en julio. Galileo recibe la orden de presentarse ante la Inquisición.

*1633, Junio 13-22: Se produce su "adjuración" ante el Santo Oficio que le condena a arresto domiciliario de por vida. Se retira a la villa "Il Gioiello" en Arcetri. Continúa trabajando sin amilanarse por la reclusión.

*1637: Anuncia su último descubrimiento: los movimientos de libración de la Luna.

*1642, enero 8: Hacia las 4:00 am. muere Galileo Galilei en Arcetri.

En el año de 1979, el papa Juan Pablo II nombró una comisión para iniciar una investigación para esclarecer los distintos aspectos del proceso al que fue sometido Galileo por aquel tribunal eclesiástico en 1633. En octubre de 1992, esta comisión papal reconoció el error del Vaticano.

Fuente:

http://www.tayabeixo.org/biografias/galileo.htm

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"...Desde 1958 en la LIADA unimos al Mundo Astronómico Iberoamericano.
Conózcanos en www.liada.net ..."

"...Desde 1958 na LIADA unimos o Mundo Astronômico Iberoamericano... "
"Conheça-nos em www.liada.net..."