quarta-feira, 20 de março de 2013

Sonda Voyager sai do Sistema Solar

A Voyager-1, lançada em 1977, é o primeiro objeto feito pelo homem a conseguir ultrapassar a heliosfera.

Da BBC
A sonda espacial Voyager-1 tornou-se o primeiro objeto feito pelo homem a deixar o Sistema Solar, de acordo com a Agência Especial Americana (Nasa). Lançada em 1977, a sonda foi criada inicialmente para estudar os planetas mais afastados da Terra, mas continuou viajando.

A Nasa diz que a Voyager acaba de entrar em uma área do espaço além da influência do Sol. Calcula-se que a região interestelar esteja a mais de 18 bilhões de quilômetros da Terra, ou 123 vezes a distância entre nosso planeta e o Sol.

Atualmente, as mensagens de rádio da Voyager-1 levam 16 horas para chegar ao nosso planeta. A Voyager-1 caminha para se aproximar de uma estrela chamada AC +793888, mas só chegará a dois anos luz de distância da estrela - e levará cerca de 40 mil anos para fazê-lo.

A Voyager-1 vinha monitorando mudanças no ambiente ao seu redor que sugeriam a proximidade da fronteira do Sistema Solar  (Foto: Nasa/BBC) 
A Voyager-1 vinha monitorando mudanças no ambiente ao seu redor que sugeriam a proximidade da fronteira do Sistema Solar (Foto: Nasa/BBC)
 
Na terça-feira (19), a União Geofísica Americana confirmou que a sonda deixou a heliosfera - a bolha de gás e campos magnéticos que tem origem no Sol. A organização aceitou um artigo sobre o assunto escrito por cientistas da Nasa, que será divulgado em breve na publicação Geophysical Research Letters. O anúncio de que a sonda deixaria o Sistema Solar já era esperado há algum tempo.

Detecção de raios cósmicos
A Voyager-1 vinha monitorando mudanças no ambiente ao seu redor que sugeriam a proximidade da fronteira do Sistema Solar - a chamada heliopausa. A sonda havia detectado um aumento no número de partículas de raios cósmicos vindo do espaço interestelar em sua direção e, ao mesmo tempo, um declínio da intensidade de partículas energéticas vindo do Sol.

Uma grande mudança, que os cientistas chamaram de 'heliopenhasco', aconteceu em 25 de agosto de 2012. "Em poucos dias, a intensidade heliosférica da radiação caiu e a intensidade de raios cósmicos subiu, como era de se esperar quando se sai da heliosfera", explicou o professor Bill Webber da Universidade Estadual do Novo México, em Las Cruces.

A Voyager-1 foi lançada em 5 de setembro de 1977 e sua "sonda irmã", a Voyager-2, em agosto do mesmo ano. O objetivo inicial das duas sondas era investigar os planetas Júpiter, Saturno, Urano e Netuno - tarefa que completaram em 1989.

Em seguida, elas foram enviadas para mais além no espaço, na direção do centro da Via Láctea. No entanto, suas fontes de energia, feitas de plutônio, devem parar de produzir eletricidade em cerca de 10 a 15 anos, quando seus instrumentos e transmissores irão parar de funcionar.

As Voyagers se tornarão "embaixadores silenciosos" da Terra enquanto se movem pela galáxia. Ambas transportam discos de cobre banhados a ouro com gravações de saudações em 60 línguas, amostras de música de diferentes culturas e épocas, sons naturais da Terra e outros sons produzidos pelo homem.

Imagem mostra galáxia com supernova a 35 milhões de anos-luz

Observatório no Chile registrou a espiral NGC 1637.
Supernova apareceu em seu interior em 1999.

Do G1, em São Paulo
Galáxia espiral NGC 1637 (Foto: ESO/Divulgação) 
Galáxia espiral NGC 1637 (Foto: ESO/Divulgação)
 
Astrônomos do Observatório Europeu do Sul que trabalham no VLT (sigla para Very Large Telescope,  que em inglês significa "telescópio muito grande"), no norte Chile, produziram uma imagem da galáxia espiral NGC 1637, a cerca de 35 milhões de anos-luz da Terra, na constelação do Rio Erídano, divulgada nesta quarta-feira (20).

Em 1999, a aparência desta galáxia foi modificada pelo aparecimento de uma supernova brilhante, nomeada SN 1999em. Supernovas são a morte ofuscante de estrelas e podem brilhar mais intensamente do que a radiação combinada de bilhões de outras estrelas.
  •  
Detalhe mostra o posicinamento da supernova SN 1999em (Foto: ESO/Divulgação) 
Detalhe mostra o posicinamento da supernova
SN 1999em (Foto: ESO/Divulgação)
 
Esta supernova foi descoberta com um telescópio construído especialmente para procurar esse tipo de objeto. Os astrônomos obtiveram muitas fotografias dela,  com o VLT, que foram depois combinadas na imagem nítida de sua galáxia "hospedeira", a NGC 1637.

Embora à primeira vista  a NGC 1637 pareça ser um objeto relativamente simétrico, ela possui algumas particularidades interessantes, informa o ESO. É um tipo de galáxia que os astrônomos chamam de espiral irregular porque seu braço mais aberto (em cima e à esquerda), estende-se em torno do núcleo a uma distância bem maior do que o braço mais compacto e curto (embaixo e à direita), que parece ter sido "cortado ao meio".

Por toda a imagem é possível ver estrelas mais próximas e galáxias mais distantes que se encontram na mesma direção no céu.

NASA to Hold News Teleconference to Discuss Planck Cosmology Findings (Update)

 
JPL/NASA News
News advisory: 2013-105                                                             March 19, 2013

NASA to Hold News Teleconference to Discuss Planck Cosmology Findings (Update)

NASA to Hold News Teleconference to Discuss Planck Cosmology Findings (Update)

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-105&cid=release_2013-105

PASADENA, Calif. -- NASA will host a news teleconference at 8 a.m. PDT (11 a.m. EDT), Thursday, March 21, to discuss the first cosmology results from Planck, a European Space Agency mission with significant NASA participation.

Planck launched into space in 2009 and has been scanning the skies ever since, mapping cosmic microwave background, or the afterglow, of the theoretical big bang that created the universe more than 13 billion years ago. NASA contributed mission-enabling technology for both of Planck's science instruments, and U.S., European and Canadian scientists work together to analyze the Planck data.

The teleconference participants are:

-- Paul Hertz, director of astrophysics, NASA Headquarters, Washington -- Charles Lawrence, U.S. Planck project scientist, NASA's Jet Propulsion Laboratory, Pasadena, Calif. -- Martin White, U.S. Planck scientist, University of California, Berkeley, Calif.; and Faculty Senior Scientist at Lawrence Berkeley Laboratory -- Krzysztof Gorski, U.S. Planck scientist, JPL -- Marc Kamionkowski, professor of physics and astronomy, John Hopkins University, Baltimore, Md.

This event previously was scheduled as a televised news conference.

Questions may be submitted via Twitter using the hashtag #AskNASA .

Visuals will be posted at the start of the teleconference on NASA's Planck website: http://www.nasa.gov/planck .

Audio of the teleconference will be streamed live on NASA's website at: http://www.nasa.gov/newsaudio . The event will also be streamed live on Ustream at: http://www.ustream.tv/nasajpl2 .

For additional information about Planck, visit: http://www.esa.int/planck .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
NASA Headquarters, Washington
j.d.harrington@nasa.gov

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Educator Workshop: How to Think Like a NASA Scientist

 
JPL/NASA News



Educator Workshop                 March 19, 2013


This is a feature from the NASA/JPL Education Office.



How to Think Like a NASA Scientist: Analyzing Data, Drawing Conclusions

Date: Saturday, April 13, 2013, 8:30 a.m. - 4:30 p.m.

Target audience: Middle and high school science and mathematics educators (but all are welcome)

Location: Theodore von Kármán Auditorium, Jet Propulsion Laboratory, Pasadena, Calif.

Overview: Learn to think like a NASA scientist - and get your students thinking like one, too! This one-day workshop will show you how to teach students to read scientific graphs and draw conclusions based on real NASA data. Experts will discuss current Earth science missions and show how the scientists, themselves, draw conclusions from these data. Participants will also receive science and math application problems to take back and use in the classroom tomorrow.

A registration fee of $25 covers continental breakfast, lunch and snacks. The deadline to register is April 5, 2013.

For more information and to register, visit: http://www.jpl.nasa.gov/education/index.cfm?page=373

-end-

Lunar Reconnaissance Orbiter Sees GRAIL's Explosive Farewell

 
JPL/NASA News
News feature: 2013-103                                                                       March 19, 2013

Lunar Reconnaissance Orbiter Sees GRAIL's Explosive Farewell

Lunar Reconnaissance Orbiter Sees GRAIL's Explosive Farewell

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-103&cid=release_2013-103

Many spacecraft just fade away, drifting silently through space after their mission is over, but not GRAIL. NASA's twin GRAIL (Gravity Recovery and Interior Laboratory) spacecraft went out in a blaze of glory on Dec. 17, 2012, when they were intentionally crashed into a mountain near the moon's north pole.

The successful mission to study the moon's interior took the plunge to get one last bit of science: with the spacecraft kicking up a cloud of dust and gas with each impact, researchers hoped to discover more about the moon's composition. However, with the moon about 380,000 kilometers (over 236,000 miles) away from Earth, the impact plumes would be difficult to observe from here. Fortunately, GRAIL had company. NASA's Lunar Reconnaissance Orbiter (LRO) is orbiting the moon as well, busily making high-resolution maps of the lunar surface. With just three weeks notice, the LRO team scrambled to get their orbiter in the right place at the right time to witness GRAIL's fiery finale.

"We were informed by the GRAIL team about three weeks prior to the impact exactly where the impact site would be," said LRO Project Scientist John Keller of NASA's Goddard Space Flight Center in Greenbelt, Md. "The GRAIL team's focus was on obtaining the highest-resolution gravity measurements possible from the last few orbits of the GRAIL spacecraft, which led to uncertainty in the ultimate impact site until relatively late."

LRO was only about 100 miles (160 kilometers) from the lunar surface at the time of the impact, and variations in gravity from massive features like lunar mountains tugged on the spacecraft, altering its orbit.

The site was in shadow at the time of the impact, so the LRO team had to wait until the plumes rose high enough to be in sunlight before making the observation. The Lyman Alpha Mapping Project (LAMP), an ultraviolet imaging spectrograph on board the spacecraft, saw mercury and enhancements of atomic hydrogen in the plume.

"The mercury observation is consistent with what the LRO team saw from the LCROSS impact in October 2009," said Keller. "LCROSS (Lunar CRater Observation and Sensing Satellite) saw significant amounts of mercury, but the LCROSS site was at the bottom of the moon's Cabeus crater, which hasn't seen sunlight for more than a billion years and is therefore extremely cold."

LRO's Lunar Reconnaissance Orbiter Camera was able to make an image of the craters from the GRAIL impacts despite their relatively small size.

The two spacecraft were relatively small -- cubes about the size of a washing machine with a mass of about 200 kilograms (440 pounds) each at the time of impact. The spacecraft were traveling about 3,800 mph (6,100 kilometers per hour) when they hit the surface.

"Both craters are relatively small, perhaps 4 to 6 meters (about 13 to 20 feet) in diameter and both have faint, dark, ejecta patterns, which is unusual," said Mark Robinson, LROC principal investigator at Arizona State University's School of Earth and Space Sciences, Tempe, Ariz. "Fresh impact craters on the moon are typically bright, but these may be dark due to spacecraft material being mixed with the ejecta."

"Both impact sites lie on the southern slope of an unnamed massif [mountain] that lies south of the crater Mouchez and northeast of the crater Philolaus," said Robinson. "The massif stands as much as 2,500 meters [about 8,202 feet] above the surrounding plains. The impact sites are at an elevation of about 700 meters [around 2,296 feet] and 1,000 meters [3,281 feet], respectively, about 500 to 800 meters [approximately 1,640 to 2,625 feet] below the summit. The two impact craters are about 2,200 meters [roughly 7,218 feet] apart. GRAIL B [renamed Flow] impacted about 30 seconds after GRAIL A [Ebb] at a site to the west and north of GRAIL A."

Lunar Reconnaissance Orbiter complemented the GRAIL mission in other ways as well. LRO's Diviner lunar radiometer observed the impact site and confirmed that the amount of heating of the surface there by the relatively small GRAIL spacecraft was within expectations. LRO's Lunar Orbiter Laser Altimeter (LOLA) instrument bounced laser pulses off the surface to build up a precise map of the lunar terrain, including the three-dimensional structure of features like mountains and craters.

"Combining the LRO LOLA topography map with GRAIL's gravity map yields some very interesting results," said Keller. "You expect that areas with mountains will have a little stronger gravity, while features like craters will have a little less. However, when you subtract out the topography, you get another map that reveals gravity differences that are not tied to the surface. It gives insight into structures deeper in the moon's interior."

JPL manages the GRAIL mission for NASA's Science Mission Directorate in Washington. GRAIL is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft.

For the mission's press kit and other information about GRAIL, visit: http://www.nasa.gov/grail . You can follow JPL News on Facebook at: http://www.facebook.com/nasajpl and on Twitter at: http://www.twitter.com/nasajpl .

The research was funded by the LRO mission, currently under NASA's Science Mission Directorate at NASA Headquarters in Washington. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Md.

Images are posted at: http://www.nasa.gov/mission_pages/LRO/news/grail-results.html

DC Agle (818) 393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

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Earth Observatory: What's New Week of 19 March 2013

The latest from NASA's Earth Observatory (19 March 2013)
------------------------------------------------------------------------

Latest Images:
http://earthobservatory.nasa.gov/IOTD/

* Baytown, Texas
http://earthobservatory.nasa.gov/IOTD/view.php?id=80673&src=eoa-iotd

* Clouds over the Southern Indian Ocean
http://earthobservatory.nasa.gov/IOTD/view.php?id=80661&src=eoa-iotd

* Belgrade, Serbia
http://earthobservatory.nasa.gov/IOTD/view.php?id=80652&src=eoa-iotd

* Submarine Vehicle Probes Beneath an Ice Sheet
http://earthobservatory.nasa.gov/IOTD/view.php?id=80657&src=eoa-iotd

* Activity at Kizimen Volcano
http://earthobservatory.nasa.gov/IOTD/view.php?id=80647&src=eoa-iotd

* Dust in Eastern China
http://earthobservatory.nasa.gov/IOTD/view.php?id=80643&src=eoa-iotd

* The Greening Arctic
http://earthobservatory.nasa.gov/IOTD/view.php?id=80637&src=eoa-iotd

* Freshwater Stores Shrank in Tigris-Euphrates Basin
http://earthobservatory.nasa.gov/IOTD/view.php?id=80613&src=eoa-iotd

--------------------

Herschel Discovers Some of the Youngest Stars Ever Seen

 
JPL/NASA News

News release: 2013-102                                                                    March 19, 2013

Herschel Discovers Some of the Youngest Stars Ever Seen

Herschel Discovers Some of the Youngest Stars Ever Seen

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-102&cid=release_2013-102

PASADENA, Calif. - Astronomers have found some of the youngest stars ever seen, thanks to the Herschel space observatory, a European Space Agency mission with important NASA contributions.

Observations from NASA's Spitzer Space Telescope and the Atacama Pathfinder Experiment (APEX) telescope in Chile, a collaboration involving the Max Planck Institute for Radio Astronomy in Germany, the Onsala Space Observatory in Sweden, and the European Southern Observatory in Germany, contributed to the findings.

Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult. The 15 newly observed protostars turned up by surprise in a survey of the biggest site of star formation near our solar system, located in the constellation Orion. The discovery gives scientists a peek into one of the earliest and least understood phases of star formation.

"Herschel has revealed the largest ensemble of such young stars in a single star-forming region," said Amelia Stutz, lead author of a paper to be published in The Astrophysical Journal and a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. "With these results, we are getting closer to witnessing the moment when a star begins to form."

Stars spring to life from the gravitational collapse of massive clouds of gas and dust. This changeover from stray, cool gas to the ball of super-hot plasma we call a star is relatively quick by cosmic standards, lasting only a few hundred thousand years. Finding protostars in their earliest, most short-lived and dimmest stages poses a challenge.

Astronomers long had investigated the stellar nursery in the Orion Molecular Cloud Complex, a vast collection of star-forming clouds, but had not seen the newly identified protostars until Herschel observed the region.

"Previous studies have missed the densest, youngest and potentially most extreme and cold protostars in Orion," Stutz said. "These sources may be able to help us better understand how the process of star formation proceeds at the very earliest stages, when most of the stellar mass is built up and physical conditions are hardest to observe."

Herschel spied the protostars in far-infrared, or long-wavelength, light, which can shine through the dense clouds around burgeoning stars that block out higher-energy, shorter wavelengths, including the light our eyes see.

The Herschel Photodetector Array Camera and Spectrometer (PACS) instrument collected infrared light at 70 and 160 micrometers in wavelength, comparable to the width of a human hair. Researchers compared these observations to previous scans of the star-forming regions in Orion taken by Spitzer. Extremely young protostars identified in the Herschel views but too cold to be picked up in most of the Spitzer data were further verified with radio wave observations from the APEX ground telescope.

"Our observations provide a first glimpse at protostars that have just begun to 'glow' at far-infrared wavelengths," said paper coauthor Elise Furlan, a postdoctoral research associate at the National Optical Astronomy Observatory in Tucson, Ariz.

Of the 15 newly discovered protostars, 11 possess very red colors, meaning their light output trends toward the low-energy end of the electromagnetic spectrum. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young. An additional seven protostars previously seen by Spitzer share this characteristic. Together, these 18 budding stars comprise only five percent of the protostars and candidate protostars observed in Orion. That figure implies the very youngest stars spend perhaps 25,000 years in this phase of their development, a mere blink of an eye considering a star like our sun lives for about 10 billion years.

Researchers hope to document chronologically each stage of a star's development rather like a family album, from before birth to early infancy, when planets also take shape.

"With these recent findings, we add an important missing photo to the family album of stellar development," said Glenn Wahlgren, Herschel Program Scientist at NASA Headquarters in Washington. "Herschel has allowed us to study stars in their infancy."

Herschel is a European Space Agency mission, with science instruments provided by a consortia of European institutes with important participation by NASA. NASA's Herschel Project Office is based at the agency's Jet Propulsion Laboratory in Pasadena, Calif. JPL is a division of the California Institute of Technology, Pasadena.

For more about Herschel, visit: http://www.nasa.gov/herschel , http://www.esa.int/SPECIALS/Herschel/index.html and http://www.herschel.caltech.edu .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
NASA Headquarters, Washington
j.d.harrington@nasa.gov


- end -


La cometa di primavera visibile per tutto marzo

La cometa Panstarrs fotograta da Gianluca Masi (fonte: Gianluca Masi, Virtual Telescope) 
 La cometa Panstarrs fotograta da Gianluca Masi (fonte: Gianluca Masi, Virtual Telescope)
 
Sarà  visibile fino alla fine di marzo la cometa di primavera, la Panstarrs. La sua luminosità si è un po' affievolita, ma è comunque sufficiente per riuscire ad individuarla all'orizzonte al momento del tramonto.

In molti l'hanno fotografata e l'Unione Italiana Astrofili (Uai ) ha raccolto molte di queste immagini in una galleria. ''Pochi sono però riusciti a vederla a occhio nudo, e comunque ore individuali si sono sempre aiutati prima con un binocolo'', dice l'astrofisico Gianluca Masi, curatore scientifico del Planetario di Roma e responsabile del Virtual Telescope. ''Riuscire a individuare la Panstarrs non è facile - spiega Masi - in quanto la cometa risente dei bagliori del crepuscolo''. Proprio per questo motivo é  possibile osservarla anche dalle città: in questo caso le luci che creano tanti problemi alle osservazioni del cielo non disturbano. ''Per riuscire a individuarla  - prosegue - nella maggior parte dei casi  un modesto binocolo per risolvere il problema e godere uno spettacolo davvero interessante''.

    La Panstarrs, dice ancora l'astrofisico, ''é  davvero molto bassa sull'orizzonte, al punto che basta un ostacolo naturale oppure un palazzo per perderla di vista''. Per questo buon punto or osservarla é  dal litorale tirrenico, visto che sul mare l'orizzonte é  completamente libero.

Nuvole permettendo, é  possibile osservarla a partire dalle 18,40 guardando verso Ovest, appena più in alto  destra rispetto al punto in cui traina il Sole. ''Con un piccolo binocolo - prosegue Masi - si nota una luce diffusa e poco più tardi, prima che il Sole tramonti completamente, si può apprezzare la coda''. La cometa resta visibile per circa un'ora, poiché tramonta fra le 19,15 e le 19,30.

Con il passare dei giorni la cometa salirà leggermente rispetto all'orizzonte, ma la sua luminosità diventerà sempre più debole. Sarà comunque possibile osservarla per tutto marzo con l'aiuto di un piccolo binocolo. Per non perdere lo spettacolo, comunque, é  possibile osservare il passaggio della cometa sul canale Ansa Scienza e Tecnica, grazie al collegamento in diretta streaming con il Virtual Telescope in programma giovedì  21 marzo alle 18,30

www.ansa.it

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