Saturday, September 3, 2016

MYSTERY - What is the Speed of Light?

What is the Speed of Light?:



Artist's impression of a spaceship making the jump to "light speed". Credit: NASA/Glenn Research Center


Since ancient times, philosophers and scholars have sought to understand light. In addition to trying to discern its basic properties (i.e. what is it made of - particle or wave, etc.) they have also sought to make finite measurements of how fast it travels. Since the late-17th century, scientists have been doing just that, and with increasing accuracy.



In so doing, they have gained a better understanding of light's mechanics and the important role it plays in physics, astronomy and cosmology. Put simply, light moves at incredible speeds and is the fastest moving thing in the Universe. It's speed is considered a constant and an unbreakable barrier, and is used as a means of measuring distance. But just how fast does it travel?



Speed of Light (c):

Light travels at a constant speed of 1,079,252,848.8 (1.07 billion) km per hour. That works out to 299,792,458 m/s, or about 670,616,629 mph (miles per hour). To put that in perspective, if you could travel at the speed of light, you would be able to circumnavigate the globe approximately seven and a half times in one second. Meanwhile, a person flying at an average speed of about 800 km/h (500 mph), would take over 50 hours to circle the planet just once.







To put that into an astronomical perspective, the average distance from the Earth to the Moon is 384,398.25 km (238,854 miles ). So light crosses that distance in about a second. Meanwhile, the average distance from the Sun to the Earth is ~149,597,886 km (92,955,817 miles), which means that light only takes about 8 minutes to make that journey.



Little wonder then why the speed of light is the metric used to determine astronomical distances. When we say a star like Proxima Centauri is 4.25 light years away, we are saying that it would take - traveling at a constant speed of 1.07 billion km per hour (670,616,629 mph) - about 4 years and 3 months to get there. But just how did we arrive at this highly specific measurement for "light-speed"?



History of Study:

Until the 17th century, scholars were unsure whether light traveled at a finite speed or instantaneously. From the days of the ancient Greeks to medieval Islamic scholars and scientists of the early modern period, the debate went back and forth. It was not until the work of Danish astronomer Øle Rømer (1644-1710) that the first quantitative measurement was made.



In 1676, Rømer observed that the periods of Jupiter's innermost moon Io appeared to be shorter when the Earth was approaching Jupiter than when it was receding from it. From this, he concluded that light travels at a finite speed, and estimated that it takes about 22 minutes to cross the diameter of Earth's orbit.







Christiaan Huygens used this estimate and combined it with an estimate of the diameter of the Earth's orbit to obtain an estimate of 220,000 km/s. Isaac Newton also spoke about Rømer's calculations in his seminal work Opticks (1706). Adjusting for the distance between the Earth and the Sun, he calculated that it would take light seven or eight minutes to travel from one to the other. In both cases, they were off by a relatively small margin.



Later measurements made by French physicists Hippolyte Fizeau (1819 - 1896) and Léon Foucault (1819 - 1868) refined these measurements further - resulting in a value of 315,000 km/s (192,625 mi/s). And by the latter half of the 19th century, scientists became aware of the connection between light and electromagnetism.



This was accomplished by physicists measuring electromagnetic and electrostatic charges, who then found that the numerical value was very close to the speed of light (as measured by Fizeau). Based on his own work, which showed that electromagnetic waves propagate in empty space, German physicist Wilhelm Eduard Weber proposed that light was an electromagnetic wave.



The next great breakthrough came during the early 20th century/ In his 1905 paper, titled "On the Electrodynamics of Moving Bodies", Albert Einstein asserted that the speed of light in a vacuum, measured by a non-accelerating observer, is the same in all inertial reference frames and independent of the motion of the source or observer.

Using this and Galileo’s principle of relativity as a basis, Einstein derived the Theory of Special Relativity, in which the speed of light in vacuum (c) was a fundamental constant. Prior to this, the working consensus among scientists held that space was filled with a "luminiferous aether" that was responsible for its propagation - i.e. that light traveling through a moving medium would be dragged along by the medium.



This in turn meant that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of that medium. However, Einstein's theory effectively  made the concept of the stationary aether useless and revolutionized the concepts of space and time.





Not only did it advance the idea that the speed of light is the same in all inertial reference frames, it also introduced the idea that major changes occur when things move close the speed of light. These include the time-space frame of a moving body appearing to slow down and contract in the direction of motion when measured in the frame of the observer (i.e. time dilation, where time slows as the speed of light approaches).



His observations also reconciled Maxwell’s equations for electricity and magnetism with the laws of mechanics, simplified the mathematical calculations by doing away with extraneous explanations used by other scientists, and accorded with the directly observed speed of light.



https://youtu.be/q74suqg5pCk



During the second half of the 20th century, increasingly accurate measurements using laser inferometers and cavity resonance techniques would further refine estimates of the speed of light. By 1972, a group at the US National Bureau of Standards in Boulder, Colorado, used the laser inferometer technique to get the currently-recognized value of 299,792,458 m/s.



Role in Modern Astrophysics:

Einstein's theory that the speed of light in vacuum is independent of the motion of the source and the inertial reference frame of the observer has since been consistently confirmed by many experiments. It also sets an upper limit on the speeds at which all massless particles and waves (which includes light) can travel in a vacuum.



One of the outgrowths of this is that cosmologists now treat space and time as a single, unified structure known as spacetime - in which the speed of light can be used to define values for both (i.e. "lightyears", "light minutes", and "light seconds"). The measurement of the speed of light has also become a major factor when determining the rate at cosmic expansion.



Beginning in the 1920's with observations of Lemaitre and Hubble, scientists and astronomers became aware that the Universe is expanding from a point of origin. Hubble also observed that the farther away a galaxy is, the faster it appears to be moving. In what is now referred to as the Hubble Parameter, the speed at which the Universe is expanding is calculated to 68 km/s per megaparsec.



https://youtu.be/cw7MTOosfeU



This phenomena, which has been theorized to mean that some galaxies could actually be moving faster than the speed of light, may place a limit on what is observable in our Universe. Essentially, galaxies traveling faster than the speed of light would cross a "cosmological event horizon", where they are no longer visible to us.



Also, by the 1990's, redshift measurements of distant galaxies showed that the expansion of the Universe has been accelerating for the past few billion years. This has led to theories like "Dark Energy", where an unseen force is driving the expansion of space itself instead of objects moving through it (thus not placing constraints on the speed of light or violating relativity).



Along with special and general relativity, the modern value of the speed of light in a vacuum has gone on to inform cosmology, quantum physics, and the Standard Model of particle physics. It remains a constant when talking about the upper limit at which massless particles can travel, and remains an unachievable barrier for particles that have mass.



Perhaps, someday, we will find a way to exceed the speed of light. While we have no practical ideas for how this might happen, the smart money seems to be on technologies that will allow us to circumvent the laws of spacetime, either by creating warp bubbles (aka. the Alcubierre Warp Drive), or tunneling through it (aka. wormholes).



https://youtu.be/lF8Ehk7JbkY



Until that time, we will just have to be satisfied with the Universe we can see, and to stick to exploring the part of it that is reachable using conventional methods.



We have written many articles about the speed of light for Universe Today. Here's How Fast is the Speed of Light?, How are Galaxies Moving Away Faster than Light?, How Can Space Travel Faster than the Speed of Light?, and Breaking the Speed of Light.



Here's a cool calculator that lets you convert many different units for the speed of light, and here's a relativity calculator, in case you wanted to travel nearly the speed of light.



Astronomy Cast also has an episode that addresses questions about the speed of light - Questions Show: Relativity, Relativity, and more Relativity.



Sources:



The post What is the Speed of Light? appeared first on Universe Today.

BINARY STARS - Talk About A Crowded Neighborhood: Closest Binary Stars With Multiple Planets Found

Talk About A Crowded Neighborhood: Closest Binary Stars With Multiple Planets Found:



Artist’s conception of the binary system with three giant planets discovered in this study. One star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed. Image courtesy of Robin Dienel/Carnegie.


The more we look, the more we see the great diversity in planetary systems around other stars. And curiously, planet hunters are finding that most star systems are very different from our own.



An example is a recently discovered system that is extremely crowded. It consists of a three giant planets in a binary (two stars) system. One star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed.



“The probability of finding a system with all these components was extremely small," said Johanna Teske from the Carnegie Institution for Science, “so these results will serve as an important benchmark for understanding planet formation, especially in binary systems.”







Teske and her team said this busy system might help explain the influence that giant planets like Jupiter have over a solar system’s architecture.



“We are trying to figure out if giant planets like Jupiter often have long and, or eccentric orbits,” Teske explained. “If this is the case, it would be an important clue to figuring out the process by which our Solar System formed, and might help us understand where habitable planets are likely to be found.”



The twin stars are named HD 133131A and HD 133131B. The former hosts two Jupiter-sized worlds and the latter a planet with a mass at least 2.5 times Jupiter’s. All three planets have “eccentric” or highly elliptical orbits. So far no smaller, rocky worlds have been detected but the team said those type of planets could be part of the system, or may have been part of the system in the past.



The two stars themselves are separated by only 360 astronomical units (AU – the distance between the Earth and the Sun, approximately 150,000,000 km or 93,000,000 miles). This is extremely close for twin stars with detected planets orbiting the individual stars. The next-closest known binary star system with planets has stars about 1,000 AU apart.



The two stars are more like fraternal twins rather than identical because they have slight different chemical compositions. The team said this could indicate that one star swallowed some baby planets early in its life, changing its composition slightly. Or another option is that the gravitational forces of the detected giant planets may have had a strong effect on fully-formed small planets, flinging them in towards the star or out into space.



But both stars are “metal poor,” meaning that most of their mass is hydrogen and helium, as opposed to other elements like iron or oxygen. This is another curious thing about this system, as most stars that host giant planets are "metal rich.”



The system was found using the Planet Finder Spectrograph, an instrument developed by Carnegie scientists and mounted on the Magellan Clay Telescopes at Carnegie’s Las Campanas Observatory. This finding represents the first exoplanet detection made based solely on data from the. PFS is able to find large planets with long-duration orbits or orbits that are very elliptical rather than circular.



This video tells more about the PFS:







You can read the team's paper here. It has been accepted for publication in the Astronomical Journal.

The post Talk About A Crowded Neighborhood: Closest Binary Stars With Multiple Planets Found appeared first on Universe Today.

JUPITER PLANET - Juno Captures Jupiter’s Enthralling Poles From 2,500 Miles

Juno Captures Jupiter’s Enthralling Poles From 2,500 Miles:



JunoCam captured this image of Jupiter's north pole region from a distance of 78,000 km (48,000 miles) above the planet.


Juno is sending data from Jupiter back to us, courtesy of the Deep Space Network, and the first images are meeting our hyped-up expectations. On August 27, the Juno spacecraft came within about 4,200 km. (2,500 miles) of Jupiter's cloud tops. All of Juno's instruments were active, and along with some high-quality images in visual and infrared, Juno also captured the sound that Jupiter produces.



Juno has captured the first images of Jupiter's north pole. Beyond their interest as pure, unprecedented eye candy, the images of the pole reveal things never before seen. They show storm activity and weather patterns that are seen nowhere else in our solar system. Even on the other gas giants.









"...like nothing we have seen or imagined before."
“First glimpse of Jupiter’s north pole, and it looks like nothing we have seen or imagined before,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “It’s bluer in color up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to -- this image is hardly recognizable as Jupiter. We’re seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features.”







The visible light images of Jupiter's north pole are very different from our usual perception of Jupiter. People have been looking at Jupiter for a long time, and the gas giant's storm bands, and the Great Red Spot, are iconic. But the north polar region looks completely different, with whirling, rotating storms similar to hurricanes here on Earth.



The Junocam instrument is responsible for the visible light pictures of Jupiter that we all enjoy. But the Jovian Infrared Auroral Mapper (JIRAM) is showing us a side of Jupiter that the naked eye will never see.







“JIRAM is getting under Jupiter’s skin, giving us our first infrared close-ups of the planet,” said Alberto Adriani, JIRAM co-investigator from Istituto di Astrofisica e Planetologia Spaziali, Rome. “These first infrared views of Jupiter’s north and south poles are revealing warm and hot spots that have never been seen before. And while we knew that the first-ever infrared views of Jupiter's south pole could reveal the planet's southern aurora, we were amazed to see it for the first time."









"No other instruments, both from Earth or space, have been able to see the southern aurora."
Even when we're prepared to be amazed by what Juno and other spacecraft show us, we are still amazed. It's impossible to see Jupiter's south pole from Earth, so these are everybody's first glimpses of it.



"No other instruments, both from Earth or space, have been able to see the southern aurora," said Adriani. "Now, with JIRAM, we see that it appears to be very bright and well-structured. The high level of detail in the images will tell us more about the aurora’s morphology and dynamics.”



[embed]https://www.youtube.com/watch?v=i9TtSCkoERw[/embed]



Beyond the juicy images of Jupiter are some sound recordings. It's been known since about the 1950's that Jupiter is a noisy planet. Now Juno's Radio/Plasma Wave Experiment (WAVE) has captured a recording of that sound.



“Jupiter is talking to us in a way only gas-giant worlds can,” said Bill Kurth, co-investigator for the Waves instrument from the University of Iowa, Iowa City. “Waves detected the signature emissions of the energetic particles that generate the massive auroras which encircle Jupiter’s north pole. These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them.”



[embed]https://www.youtube.com/watch?v=slE2i0O0pDY[/embed]



Oddly enough, that's pretty much exactly what I expected Jupiter to sound like. Like something from an early sci-fi film.



There's much more to come from Juno. These images and recordings of Jupiter are just the result of Juno's first orbit. There are over 30 more orbits to come, as Juno examines the gas giant as it orbits beneath it.













The post Juno Captures Jupiter’s Enthralling Poles From 2,500 Miles appeared first on Universe Today.

GREAT IMAGES - How Cold Are Black Holes?

How Cold Are Black Holes?:

Today we’re going to have the most surreal conversation. I’m going to struggle to explain it, and you’re going to struggle to understand it. And only Stephen Hawking is going to really, truly, understand what’s actually going on.

But that’s fine, I’m sure he appreciates our feeble attempts to wrap our brains around this mind bending concept.

All right? Let’s get to it. Black holes again. But this time, we’re going to figure out their temperature.

The very idea that a black hole could have a temperature strains the imagination. I mean, how can something that absorbs all the matter and energy that falls into it have a temperature? When you feel the warmth of a toasty fireplace, you’re really feeling the infrared photons radiating from the fire and surrounding metal or stone.

And black holes absorb all the energy falling into them. There is absolutely no infrared radiation coming from a black hole. No gamma radiation, no radio waves. Nothing gets out.

heic1413a-580x454.jpg
As with most galaxies, a supermassive black hole lies at the heart of NGC 5548. Credit: ESA/Hubble and NASA. Acknowledgement: Davide de Martin
Now, supermassive black holes can shine with the energy of billions of stars, when they become quasars. When they’re actively feeding on stars and clouds of gas and dust. This material piles up into an accretion disk around the black hole with such density that it acts like the core of a star, undergoing nuclear fusion.

But that’s not the kind of temperature we’re talking about. We’re talking about the temperature of the black hole’s event horizon, when it’s not absorbing any material at all.

The temperature of black holes is connected to this whole concept of Hawking Radiation. The idea that over vast periods of time, black holes will generate virtual particles right at the edge of their event horizons. The most common kind of particles are photons, aka light, aka heat.

Normally these virtual particles are able to recombine and disappear in a puff of annihilation as quickly as they appear. But when a pair of these virtual particles appear right at the event horizon, one half of the pair drops into the black hole, while the other is free to escape into the Universe.

From your perspective as an outside observer, you see these particles escaping from the black hole. You see photons, and therefore, you can measure the temperature of the black hole.

PIA18919: How Black Hole Winds Blow (Artist's Concept)
Artist’s concept of the black hole at the center of the Pinwheel Galaxy. Credit: NASA/JPL-Caltech
The temperature of the black hole is inversely proportional to the mass of the black hole and the size of the event horizon. Think of it this way. Imagine the curved surface of a black hole’s event horizon. There are many paths that a photon could try to take to get away from the event horizon, and the vast majority of those are paths that take it back down into the black hole’s gravity well.

But for a few rare paths, when the photon is traveling perfectly perpendicular to the event horizon, then the photon has a chance to escape. The larger the event horizon, the less paths there are that a photon could take.

Since energy is being released into the Universe at the black hole’s event horizon, but energy can neither be created or destroyed, the black hole itself provides the mass that supplies the energy to release these photons.

The black hole evaporates.

The most massive black holes in the Universe, the supermassive black holes with millions of times the math of the Sun will have a temperature of 1.4 x 10^-14 Kelvin. That’s low. Almost absolute zero, but not quite.

Artist's impression of a feeding stellar-mass black hole. Credit: NASA, ESA, Martin Kornmesser (ESA/Hubble)
Artist’s impression of a feeding stellar-mass black hole. Credit: NASA, ESA, Martin Kornmesser (ESA/Hubble)
A solar mass black hole might have a temperature of only .0.00000006 Kelvin. We’re getting warmer.

Since these temperatures are much lower than the background temperature of the Universe – about 2.7 Kelvin, all the existing black holes will have an overall gain of mass. They’re absorbing energy from the Cosmic Background Radiation faster than they’re evaporating, and will for an incomprehensible amount of time into the future.

Until the background temperature of the Universe goes below the temperature of these black holes, they won’t even start evaporating.

A black hole with the mass of the Earth is still too cold.

Only a black hole with about the mass of the Moon is warm enough to be evaporating faster than it’s absorbing energy from the Universe.

As they get less massive, they get even hotter. A black hole with the mass of the asteroid Ceres would be 122 Kelvin. Still freezing, but getting warmer.

A black hole with half the mass of Vesta would blaze at more than 1,200 Kelvin. Now we’re cooking!

Less massive, higher temperatures.

When black holes have lost most of their mass, they release the final material in a tremendous blast of energy, which should be visible to our telescopes.

Artist's conception of the event horizon of a black hole. Credit: Victor de Schwanberg/Science Photo Library
Artist’s conception of the event horizon of a black hole. Credit: Victor de Schwanberg/Science Photo Library
Some astronomers are actively searching the night sky for blasts from black holes which were formed shortly after the Big Bang, when the Universe was hot and dense enough that black holes could just form.

It took them billions of years of evaporation to get to the point that they’re starting to explode now.

This is just conjecture, though, no explosions have ever been linked to primordial black holes so far.

It’s pretty crazy to think that an object that absorbs all energy that falls into it can also emit energy. Well, that’s the Universe for you. Thanks for helping us figure it out Dr. Hawking.

The post How Cold Are Black Holes? appeared first on Universe Today.

Quebec Canada Aurora and Manicouagan Crater

Aurora and Manicouagan Crater: An astronaut aboard the International Space Station adjusted the camera for night imaging and captured the green veils and curtains of an aurora that spanned thousands of kilometers over Quebec, Canada.


Original enclosures:

NASA IMAGE A Black Hole Story Told by a Cosmic Blob and Bubble

A Black Hole Story Told by a Cosmic Blob and Bubble: Two cosmic structures show evidence for a remarkable change in behavior of a supermassive black hole in a distant galaxy.


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Perseid Meteor Shower 2016 from West Virginia

Perseid Meteor Shower 2016 from West Virginia: In this 30 second exposure, a meteor streaks across the sky during the annual Perseid meteor shower Friday, Aug. 12, 2016 in Spruce Knob, West Virginia.


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NASA IMAGE Supernova Ejected from the Pages of History

Supernova Ejected from the Pages of History: A new look at the debris from an exploded star in our galaxy has astronomers re-examining when the supernova actually happened.


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NASA IMAGE Speeding Towards Jupiter's Pole

Speeding Towards Jupiter's Pole: Jupiter's north polar region is coming into view as NASA's Juno spacecraft approaches the giant planet. This view of Jupiter was taken on August 27, when Juno was 437,000 miles (703,000 kilometers) away. The Juno mission successfully executed its first of 36 orbital flybys of Jupiter.


Original enclosures:


NASA IMAGE An Age-defying Star

An Age-defying Star: An age-defying star designated as IRAS 19312+1950 exhibits features characteristic of a very young star and a very old star. The object stands out as extremely bright inside a large, chemically rich cloud of material, as shown in this image from NASA’s Spitzer Space Telescope.


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Good Morning From the International Space Station

Good Morning From the International Space Station: Expedition 48 Commander Jeff Williams of NASA shared this sunrise panorama taken from his vantage point aboard the International Space Station, writing, "Morning over the Atlantic…this one will hang on my wall."


Original enclosures:


NASA IMAGE Ceres' Mountain Ahuna Mons: Side View

Ceres' Mountain Ahuna Mons: Side View: Ceres' lonely mountain, Ahuna Mons, is seen in this simulated perspective view. The elevation has been exaggerated by a factor of two. The view was made using enhanced-color images from NASA's Dawn mission.


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Jupiter Down Under

Jupiter Down Under: This image from NASA's Juno spacecraft provides a never-before-seen perspective on Jupiter's south pole.


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Tuesday, August 9, 2016

Con cò bé bé biết đi xe đạp - CHUYỂN ĐỘNG BỐN PHƯƠNG





Thursday, July 21, 2016

UFO SIGHTINGS 2016 | Strange lights are recorded on Sky Lahore Pakistan

Outro oceano debaixo da terra na cidade de Juína MT

Outro oceano debaixo da terra na cidade de Juína MT



Pesquisadores descobriram um pequeno diamante que aponta para a existência de um grande depósito de água sob o manto da Terra. Seu volume poderia preencher três vezes os oceanos que conhecemos.


O principal autor do estudo, Graham Pearson, membro da Universidade de Alberta, no Canadá, disse que “Uma das razões da Terra ser um planeta dinâmico é a presença de água em seu interior. As mudanças da água dependem da forma como o mundo funciona”.

Depois de discutir a teoria há décadas, os cientistas relatam que finalmente encontraram um grande oceano no manto da Terra, três vezes maior do que os oceanos que conhecemos.

Esta descoberta surpreendente sugere que a água da superfície vem do interior do planeta como parte de um ciclo integrado da água, desbancando a teoria dominante de que a água foi trazida para a Terra por cometas gelados que passaram por aqui há milhões anos.

Cada vez mais os cientistas estão aprendendo sobre a composição de nosso planeta, compreendendo os acontecimentos relacionados às mudanças climáticas. O clima e o mar estão intimamente relacionados com a atividade tectônica que tem estado continuamente vibrando sob nossos pés.

Assim, os pesquisadores acreditam que a água na superfície da Terra poderia ter vindo do interior do planeta, tendo sido “impulsionada” para a superfície por meio da atividade geológica.


Nas profundezas desse oceano, corre um rio sem que a água doce se misture com a salgada.
Estudo Diz: Água subterrânea cobriria toda a superfície do planeta
Depois de inúmeros estudos e cálculos complexos para testar suas teorias, os pesquisadores acreditam ter encontrado um reservatório gigante de água numa zona de transição entre as camadas superior e inferior do manto, uma região que se encontra em algum lugar entre 400 e 660 km abaixo da superfície da terra.

Como sabemos, a água ocupa a maior parte da área de superfície do nosso planeta, que é paradoxalmente chamado de Terra. Embora seja verdade que, em comparação com o diâmetro terrestre a profundidade dos oceanos represente apenas uma fina camada semelhante à casca de uma cebola, descobrimos agora que a presença deste precioso líquido não está limitada à superfície visível.

Na realidade, a cerca de centenas de quilômetros de profundidade no subsolo há também enormes volumes de água, com uma importância fundamental para a compreensão da dinâmica geológica do planeta. Quase um oceano no centro da Terra.

A descoberta do oceano subterrâneo

A importante descoberta foi realizada por pesquisadores canadenses, que se basearam em um diamante encontrado numa rocha, em 2008, em uma área conhecida como Juína, no estado do Mato Grosso, Brasil.


A descoberta ocorreu por acidente, pois a equipe que estava, na realidade, à procura de outro mineral, ter comprado o diamante de alguns garimpeiros que o tinham encontrado através de uma coleta de cascalho realizada em um rio raso. Ao analisar a pedra detalhadamente um estudante descobriu, um ano depois, que o diamante, de apenas três milímetros de diâmetro e de pouco valor comercial, continha em sua composição um mineral chamado ringwoodite, que até agora só tinha sido encontrado em rochas de meteoritos e que contém significativa quantidade de água. No entanto, a confirmação final da presença deste mineral levou muitos anos, pois foi necessária a realização de vários testes e análises científicas.

De onde vem este mineral?

A análise detalhada da amostra encontrada revelou que, neste caso, o mineral não provinha de meteoritos, mas do manto da Terra, a uma profundidade de cerca de 410 e 660 km, em uma área que é conhecida como “zona de transição”.

Anteriormente, discutia-se muito sobre a possibilidade da existência de grandes quantidades de água muitos quilômetros abaixo do subsolo, mas nunca tinha sido antes demonstrada nenhuma prova real de tal teoria, que tem implicações muito importantes para a forma como entendemos os fenômenos geológicos planetários, pois acredita-se que este é o mineral mais abundante na zona do manto. Desta forma, como a amostra encontrada possui até 1,5 por cento de seu peso em água, pode-se afirmar que existem volumes de água realmente extraordinários, como um grande oceano.

Esta descoberta é, sem dúvida, uma das mais importantes realizadas no campo da geologia nos últimos anos, e forçará os peritos a modificarem, até certo ponto, a abordagem que se tem utilizado até agora para analisar fenômenos como vulcanismo, placas tectônicas e muitos outros processos de importância na compreensão da dinâmica da Terra – cujo nome, depois dessa descoberta, se tornou ainda mais paradoxal.


A peculiaridade desta descoberta é que esta água não existe em qualquer um dos três estados que conhecemos: líquido, sólido ou gasoso. A água foi encontrada em estruturas moleculares de formações rochosas no interior da Terra.

Uma concentração tão importante de água trás uma mudança significativa nas teorias relacionadas com a origem da água na superfície da Terra.


Esta descoberta é a prova de que nas partes mais profundas do nosso planeta, a água pode ser armazenada. Fato este que poderá colocar fim em uma polêmica de 25 anos, sobre se o centro da terra é seco ou úmido em algumas áreas.

A capacidade de armazenar água em seu interior não é exclusiva da Terra. Outros planetas, como Marte, podem conter grandes quantidades de água, algo que nos faz pensar se o planeta vermelho poderia abrigar vida.







Thursday, July 7, 2016

UFOS IN GERMANY - Alien ship UFO Seen In Germany Multiple witnesses 2016

Huge Cross Shaped Object In The Sky | UFO Sightings Cross Shaped Object ...





Monday, July 4, 2016

NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres

NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres:



New Horizons trajectory and the orbits of Pluto and 2014 MU69.


In an ‘Independence Day’ gift to a slew of US planetary research scientists, NASA has granted approval to nine ongoing missions to continue for another two years this holiday weekend.



The biggest news is that NASA green lighted a mission extension for the New Horizons probe to fly deeper into the Kuiper Belt and decided to keep the Dawn probe at Ceres forever, rather than dispatching it to a record breaking third main belt asteroid.



And the exciting extension news comes just as the agency’s Juno probe is about to ignite a July 4 fireworks display on July 4 to achieve orbit at Jupiter - detailed here.



“Mission approved!” the researchers gleefully reported on the probes Facebook and Twitter social media pages.



“Our extended mission into the #KuiperBelt has been approved. Thanks to everyone for following along & hopefully the best is yet to come.









The New Horizons spacecraft will now continue on course in the Kuiper Belt towards an small object known as 2014 MU69, to carry out the most distant close encounter with a celestial object in human history.



“Here's to continued success!”



The spacecraft will rendezvous with the ancient rock on New Year’s Day 2019.



Researchers say that 2014 MU69 is considered as one of the early building blocks of the solar system and as such will be invaluable to scientists studying the origin of our solar system how it evolved.



It was almost exactly one year ago on July 14, 2015 that New Horizons conducted Earth’s first ever up close flyby and science reconnaissance of Pluto - the most distant planet in our solar system and the last of the nine planets to be explored.















The immense volume of data gathered continues to stream back to Earth every day.



“The New Horizons mission to Pluto exceeded our expectations and even today the data from the spacecraft continue to surprise,” said NASA’s Director of Planetary Science Jim Green at NASA HQ in Washington, D.C.



“We’re excited to continue onward into the dark depths of the outer solar system to a science target that wasn’t even discovered when the spacecraft launched.”













While waiting for news on whether NASA would approve an extended mission, the New Horizons engineering and science team already ignited the main engine four times to carry out four course changes in October and November 2015, in order to preserve the option of the flyby past 2014 MU69 on Jan 1, 2019.



Green noted that mission extensions into fiscal years 2017 and 2018 are not final until Congress actually passes sufficient appropriation to fund NASA’s Planetary Science Division.



“Final decisions on mission extensions are contingent on the outcome of the annual budget process.”





Tough choices were made even tougher because the Obama Administration has cut funding for the Planetary Sciences Division - some of which was restored by a bipartisan majority in Congress for what many consider NASA ‘crown jewels.’



NASA’s Dawn asteroid orbiter just completed its primary mission at dwarf planet Ceres on June 30, just in time for the global celebration known as Asteroid Day.



“The mission exceeded all expectations originally set for its exploration of protoplanet Vesta and dwarf planet Ceres,” said NASA officials.



The Dawn science team had recently submitted a proposal to break out of orbit around the middle of this month in order to this conduct a flyby of the main belt asteroid Adeona.



Green declined to approve the Dawn proposal, citing additional valuable science to be gathered at Ceres.



The long-term monitoring of Ceres, particularly as it gets closer to perihelion – the part of its orbit with the shortest distance to the sun -- has the potential to provide more significant science discoveries than a flyby of Adeona,” he said.



Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.



The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.



The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves.



Dawn will remain at its current altitude at LAMO for the rest of its mission, and indefinitely afterward, even when no further communications are possible.



Green based his decision on the mission extensions on the biannual peer review scientific assessment by the Senior Review Panel.



The other mission extension - contingent on available resources - are: the Mars Reconnaissance Orbiter (MRO), Mars Atmosphere and Volatile EvolutioN (MAVEN), the Opportunity and Curiosity Mars rovers, the Mars Odyssey orbiter, the Lunar Reconnaissance Orbiter (LRO), and NASA’s support for the European Space Agency’s Mars Express mission.



Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news.



Ken Kremer











The post NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres appeared first on Universe Today.

EARTH PLANET - Earth at Aphelion 2016

Earth at Aphelion 2016:



Sunset over Naples, Florida. Image credit: Dave Dickinson


Having a great July 4th? The day gives us another cause to celebrate, as the Earth reaches aphelion today, or our farthest point to our host star.



Aphelion is the opposite of the closest point of the year, known as perihelion. Note that the 'helion' part only applies to things in solar orbit, perigee/apogee for orbit 'round the Earth, apolune/perilune for orbit around the Moon, and so on. You'll hear the words apijove and perijove bandied about this week a bit, as NASA's Juno spacecraft enters orbit around Jupiter tonight. And there are crazier and even more obscure counterparts out there, such as peribothron and apobothron (orbiting a black hole) and apastron/periastron (orbiting a star other than our Sun). And finally, there's the one-size fits all generic periapsis and apoapsis, good for all occasions and ending pedantic arguments.



In the 21st century, aphelion for the Earth can actually fall anywhere from July 2nd to the 7th. The once every four year leap day is the primary driver in this oscillation, and the exclusion of a century leap day in 2100 — the first such exclusion since 1900 — will reset things even farther astray.







In 2016, the Moon reaches New on July 4th at 11:01 Universal Time (UT) just over five hours prior to aphelion, marking the start of lunation 1157. The sighting of the waxing crescent Moon also marks the end of the Muslim fasting month of Ramadan.



Earth reaches aphelion at 16:24 UT today, 1.0168 AU from the Sun. This year's close occurrence of aphelion versus a New Moon won't get topped until 2054, with an aphelion versus New Moon just 5 hours 6 minutes apart. The 2016 coincidence is also the closest since the start of the 21st century.



Fun fact: we're headed towards an aphelion maximum just 6,590 kilometers off of the mean on July 4th, 2019, the widest for the 21st century. Mean distance from the Sun at aphelion is 1.0167 AU (152,097,701 km). Aphelion for the Earth can range over a variation of 21,225 kilometers for the 21st century.







It's a happy circumstance that Earth reaches aphelion in our current epoch in the midst of northern hemisphere summer, and just a few weeks after the June solstice. The eccentricity of the Earth's orbit actually varies from near-circular to 0.0679 and back over the span of 413,000 years. In our current epoch, the eccentricity of our orbit is 0.017 and decreasing. Add this variation to changes in the axial tilt of our planet and orbital obliquity, and you have what are known as Milankovitch Cycles. One only has to look at Mars's wacky orbit with an eccentricity of 0.0934 to see what a difference it makes. Ironically, Mars reaches perihelion in October 29th, 2016, and will make a very close pass near next opposition pass in 2018.







Want to prove it for yourself? You can indeed 'observe' aphelion. The trick is to image the solar disk using the same rig and settings... about six months apart. At aphelion, the solar disk is 31.6' across, versus 32.7' across at perihelion. This variation is slight, but you can indeed see the subtle difference side by side:







Aphelion means a smaller apparent Sun, a good target for a total solar eclipse. Stick around until July 2nd, 2019 and you'll see just that, as a total solar eclipse occurs near aphelion for South America and the southern Pacific at 4 minutes and 33 seconds in central duration.







This month also sees another special treat, as all classical planets enter the evening sky.



More to come on that soon. For now, happy 4th of July, and merry aphelion!

The post Earth at Aphelion 2016 appeared first on Universe Today.

STARS DE L'UNIVERS - Stars Are The Universe’s Neat Freaks

Stars Are The Universe’s Neat Freaks:



The Andromeda Galaxy, viewed using conventional optics and IR. Credit: Kitt Peak National Observatory


Imagine, if you will, that the Universe was once a much dirtier place than it is today. Imagine also that what we see around us, a relatively clean and unobscured Universe, is the result of billions of years of stars behaving like giant celestial Roombas, cleaning up the space around them in preparation for our arrival. According to a set of recently published catalogues, which detail the latest findings from the ESA's Herschel Space Observatory, this description is actually quite fitting.



These catalogues represents the work of an international team of over 100 astronomers who have spent the past seven years analyzing the infrared images taken by the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS). Presented earlier this week at the National Astronomy Meeting in Nottingham, this catalogue revealed that as early as 1 billion years ago, the Universe looked much different than it does today.



In order to put this research into context, it is important to understand the important of infrared astronomy. Prior to the deployment of missions like Herschel (which was launched in 2009), astronomers were unable to see a good portion of the light emitted by stars and galaxies. With roughly half of this light being absorbed by interstellar dust grains, research into the birth and lives of galaxies was difficult.







But thanks to surveys like Herschel ATLAS - as well NASA's Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE) - astronomers have been able to account for this missing energy. And what they have seen (especially from this latest survey) has been quite remarkable, presenting a Universe that is far denser than previously expected.



Last week (Friday, June 29th), during the final day of the National Astronomy Meeting, the first of the catalogues was presented. The images they showed gave all those present a glimpse of the unseen stars and galaxies that have existed over the last 12 billion years of cosmic history. In sum,  over half-a-million far-infrared sources have been spotted by the Herschel-ATLAS survey, and what they revealed was fascinating.



Many of these sources were galaxies that are nearby and similar to our own, and which are detectable using using conventional telescopes. The others were much more distant, their light taking billions of years to reach us, and were obscured by concentrations of cosmic dust. The most distant of these galaxies were roughly 12 billion light-years away, which means that they appeared as they would have 12 billion years ago.



Ergo, astronomers now know that 12 billion years ago (i.e. shortly after the Big Bang)., stars and galaxies were much dustier than they are now. They further concluded that the evolution of our galaxies since shortly after the Big Bang has essentially been a major clean-up effort, as stars gradually absorbed the dust that obscured their light, thus making it the more "visible" place it is today.







The data released by the survey includes several maps and additional files which were described in an article produced by Dr. Elisabetta Valiante and a research team from Cardiff University - titled "The Herschel-ATLAS Data Release 1 Paper I: Maps, Catalogues and Number Counts". As Dr. Valiante told Universe Today via email:



"Gas and dust are the main components of stars: they collapse to form stars and they are ejected at the end of stars’ life. The interesting thing that has been discovered thanks to the Herschel data is that the two phenomena are not in equilibrium. We knew this was true 10 billion years ago, but we expected, according to the current models, that some equilibrium was reached at more recent times. Instead, the amount of dust in galaxies 5 billion years ago was much larger than the amount we see in galaxies today: this was unexpected."
Until recently, such a survey would have been impossible due to the fact that many of these infrared sources would have  been invisible to astronomers. The reason for this, which was revealed by the survey, was that these galaxies were so dusty that they would have been virtually impossible to detect with conventional optics. What's more, their light would have been gravitationally magnified by intervening galaxies.



The huge size of the survey has also meant that changes that have occurred in galaxies - relatively recent in cosmic history - can be studied for the first time. For instance, the survey showed that even only one billion years in the past, a small fraction of the age of the universe, galaxies were forming stars at a faster rate and contained more dust than they do today.







Dr. Nathan Bourne - from the University of Edinburgh - is the lead author of another other paper describing the catalogues. As he told Universe Today via email:



“We can think of galaxies as big recycling machines. When they form, they accrete gas (mostly hydrogen and helium, with traces of lithium and a couple of other elements) from the universe around them, and they turn it into stars. As time goes on, the stars pump this gas back out into the galaxy, into the interstellar medium. Due to the nuclear processes within the stars, the gas is now enriched by heavy elements (what we call metals, though they include both metals and non-metals), and some of these form microscopic solid particles of dust, as a sort of by-product.



"But there are still stars forming, and the next generations of stars recycle this interstellar material, and now that it contains heavy elements and dust, things are a bit different, and planets can also form around the new stars, from accumulations of this heavy material. So, if you look at the big picture, when the first galaxies started forming within the first billion years after the Big Bang, they began using up the gas around them, and then while they are active they fill their interstellar medium up with gas and dust, but by the end of a galaxy's lifecycle, it has used up all this gas and dust, and you could say that it has cleaned itself.”
The catalogues and maps of the hidden universe are a triumph for the Herschel team. Despite the fact that the last information obtained by the Herschel observatory was back in 2013, the maps and catalogues produced from its years of service have become vital to astronomers. In addition to showing the Universe's hidden energy, they are also laying the groundwork for future research.







"Now we need to explain why there is dust where we did not expect to find it." said Valiante. "And to explain this, we need to change our theories about how the Universe evolves. Our data poses a challenge we have accepted, but we haven’t overcome it yet!"



"[W]e understand a lot more about how galaxies evolve," added Bourne, "about when most of the stars formed, what happens to the gas and dust as galaxies evolve, and how rapidly the star-forming activity in the Universe as a whole has faded in the latter half of the Universe's history. It's fair to say that this understanding comes from having a whole suite of different types of instruments studying different aspects of galaxies in complementary ways, but Herschel has certainly contributed a major part of that effort and will have a lasting legacy."



The implications of these findings are also likely to have a far-reaching effect, ranging from cosmology and astronomy, to perhaps shedding some light on that tricky Fermi paradox. Could it be intelligent life that emerged billions of years ago didn't venture to other star systems because they couldn't see them? Just a thought...



This data release from the H-ATLAS team was coordinated with releases made in late June from the Herschel Extragalactic Project (HELP) team and the Herschel Multi-tiered Extragalactic Survey (HerMES). H-ATLAS and HerMES are parts of the EU Research Executive Agency's HELP program, which brings together various extragalactic surveys carried out by Herschel and combines them with major surveys conducted by other observatories to give the Herschel mission a lasting legacy.



Further Reading: Royal Astronomical Society, ESA

The post Stars Are The Universe’s Neat Freaks appeared first on Universe Today.

Juno Snaps Final View of Jovian System Ahead of ‘Independence Day’ Orbital Insertion Fireworks Tonight – Watch Live

Juno Snaps Final View of Jovian System Ahead of ‘Independence Day’ Orbital Insertion Fireworks Tonight – Watch Live:



This is the final view taken by the JunoCam instrument on NASA's Juno spacecraft before Juno's instruments were powered down in preparation for orbit insertion. Juno obtained this color view on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter.  See timelapse movie below.  Credits: NASA/JPL-Caltech/MSSS


After a nearly 5 year odyssey across the solar system, NASA’s solar powered Juno orbiter is all set to ignite its main engine late tonight and set off a powerful charge of do-or-die fireworks on America’s ‘Independence Day’ required to place the probe into orbit around Jupiter - the ‘King of the Planets.’



To achieve orbit, Juno must will perform a suspenseful maneuver known as ‘Jupiter Orbit Insertion’ or JOI tonight, Monday, July 4, upon which the entire mission and its fundamental science hinges. There are no second chances!



You can be part of all the excitement and tension building up to and during that moment, which is just hours away - and experience the ‘Joy of JOI’ by tuning into NASA TV tonight!



Watch the live webcast on NASA TV featuring the top scientists and NASA officials starting at 10:30 p.m. EDT: https://www.nasa.gov/nasatv









And for a breathtaking warm-up act, Juno’s on board public outreach JunoCam camera snapped a final gorgeous view of the Jovian system showing Jupiter and its four largest moons, dancing around the largest planet in our solar system.



The newly released color view image was taken on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter.



It shows a dramatic view of the clouds bands of Jupiter, dominating a spectacular scene that includes the giant planet's four largest moons -- Io, Europa, Ganymede and Callisto.



NASA also released this new time-lapse JunoCam movie today:



https://youtu.be/kjfQCTat-8s



Video caption: Juno's Approach to Jupiter: After nearly five years traveling through space to its destination, NASA's Juno spacecraft will arrive in orbit around Jupiter on July 4, 2016. This video shows a peek of what the spacecraft saw as it closed in on its destination. Credits: NASA/JPL-Caltech/MSSS





The spacecraft is approaching Jupiter over its north pole, affording an unprecedented perspective on the Jovian system - “which looks like a mini solar system,” says Juno Principal Investigator and chief scientist Scott Bolton, from the Southwest Research Institute (SwRI) in San Antonio, Tx, at today’s media briefing at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.



The 35-minute-long main engine burn is preprogrammed to start at 11:18 p.m. EDT. It is schedule to last until approximately 11:53 p.m.



JOI is required to slow the spacecraft so it can be captured into the gas giant’s orbit as it closes in over the north pole.









Juno is the fastest spacecraft ever to arrive at Jupiter and is moving at over 165,000 mph relative to Earth and 130,000 mph relative to Jupiter.



After a five-year and 2.8 Billion kilometer (1.7 Billion mile) outbound trek to the Jovian system and the largest planet in our solar system and an intervening Earth flyby speed boost, the moment of truth for Juno is now inexorably at hand.



Signals traveling at the speed of light take 48 minutes to reach Earth, said Rick Nybakken, Juno project manager from NASA's Jet Propulsion Laboratory, at the media briefing.





So the main engine burn, which is fully automated, will already be over for some 13 minutes before the first indications of the outcome reach Earth via a series of Doppler shifts and tones.



“The engine burn will slow Juno by 542 meters/seconds and is fully automated as it approaches over Jupiter’s North Pole,” explained Nybakken.



“The long five year cruise enabled us to really learn about the spacecraft and how it operates.”



As it travels through space, the basketball court sized Juno is spinning like a windmill with its 3 giant solar arrays.



“Juno is also the farthest mission to rely on solar power. The solar panels are 60 square meters in size. And although they provide only 1/25th the power at Earth, they still provide over 500 watts of power at Jupiter.”



The protective cover that shields Juno's main engine from micrometeorites and interstellar dust was opened on June 20.



During a 20 month long science mission - entailing 37 orbits lasting 14 days each – the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s origin and evolution.



“Jupiter is the Rosetta Stone of our solar system,” says Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”



During the orbits, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet's origins, structure, atmosphere and magnetosphere.







The $1.1 Billion Juno was launched on Aug. 5, 2011 from Cape Canaveral, Florida atop the most powerful version of the Atlas V rocket augmented by 5 solid rocket boosters and built by United Launch Alliance (ULA). That same Atlas V 551 version just launched MUOS-5 for the US Navy on June 24.









Along the way Juno made a return trip to Earth on Oct. 9, 2013 for a flyby gravity assist speed boost that enabled the trek to Jupiter.



The flyby provided 70% of the velocity compared to the Atlas V launch, said Nybakken.



During the Earth flyby (EFB), the science team observed Earth using most of Juno’s nine science instruments since the slingshot also serves as an important dress rehearsal and key test of the spacecraft’s instruments, systems and flight operations teams.



Juno also went into safe mode - something the team must avoid during JOI.



What lessons were learned from the safe mode event and applied to JOI, I asked?



“We had the battery at 50% state of charge during the EFB and didn't accurately predict the sag on the battery when we went into eclipse. We now have a validated high fidelity power model which would have predicted that sag and we would have increased the battery voltage,” Nybakken told Universe Today



“It will not happen at JOI as we don't go into eclipse and are at 100% SOC. Plus the instruments are off which increases our power margins.”





Junocam has took some striking images of Earth as it sped over Argentina, South America and the South Atlantic Ocean, as it came within 347 miles (560 kilometers) of the surface.

For example the dazzling portrait of our Home Planet high over the South American coastline and the Atlantic Ocean.



For a hint of what’s to come, see our colorized Junocam mosaic of land, sea and swirling clouds, created by Ken Kremer and Marco Di Lorenzo

















Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news.



Ken Kremer















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THE UNIVERSE - Messier 17 (M17) – the Omega Nebula

Messier 17 (M17) – the Omega Nebula:



The rose-coloured star forming region Messier 17, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.. Credit: ESO/Subaru Telescope (NAOJ)/Hubble Space Telescope


Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 17 nebula – aka. The Omega Nebula (and a few other names).



In the 18th century, while searching the night sky for comets, French astronomer Charles Messier began noticing a series of “nebulous objects” in the night sky. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of these objects,. Known to posterity as the Messier Catalog, this list has come to be one of the most important milestones in the research of Deep Sky objects.



One of these is the star-forming nebula known as Messier 17 - or as it's more famously known, the Omega Nebula (or Swan Nebula, Checkmark Nebula, and Horseshoe Nebula). Located in the Sagittarius constellation, this beautiful nebula is considered one of the brightest and most massive star-forming regions of our galaxy.



Description:

From its position in space some 5,000 to 6,000 light years from Earth, the "Omega" nebula occupies a region as large as 40 light years across, with its brightest porition covering a 15 light year expanse. Like many nebulae, this giant cosmic cloud of interstellar matter is a starforming region in the Sagittarius or Sagittarius-Carina arm of our Milky Way galaxy.



What you see is the hot hydrogen gas that is illuminated when its particles are excited by the hottest of the stars that have just formed within the nebula. Also, some of the light is being reflected by the nebula's own dust. These remain hidden by dark obscuring material, and we know their presence only through the detection of their infrared radiation.







In an study titled "Interstellar Weather Vanes: GLIMPSE Mid-Infrared Stellar-Wind Bowshocks in M17 and RCW49", astronomer Matthew S. Povich (et al.) of the University of Wisconsin-Madison said of M17:



"We report the discovery of six infrared stellar-wind bowshocks in the Galactic massive star formation regions M17 and RCW49 from Spitzer GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) images. The InfraRed Array Camera (IRAC) on the Spitzer Space Telescope clearly resolves the arc-shaped emission produced by the bowshocks. We use the stellar SEDs to estimate the spectral types of the three newly-identified O stars in RCW49 and one previously undiscovered O star in M17. One of the bowshocks in RCW49 reveals the presence of a large-scale flow of gas escaping the HII region. Radiation-transfer modeling of the steep rise in the SED of this bowshock toward longer mid-infrared wavelengths indicates that the emission is coming principally from dust heated by the star driving the shock. The other 5 bowshocks occur where the stellar winds of O stars sweep up dust in the expanding HII regions."
Is Messier 17 still actively producing stars? You bet. Even protostars have been discovered hiding in its folds. As M. Nielbock (et al), wrote in 2008:



"For the first time, we resolve the elongated central infrared emission of the large accretion disk in M 17 into a point-source and a jet-like feature that extends to the northeast. We regard the unresolved emission as to originate from an accreting intermediate to high-mass protostar. In addition, our images reveal a weak and curved southwestern lobe whose morphology resembles that of the previously detected northeastern one. We interpret these lobes as the working surfaces of a recently detected jet interacting with the ambient medium at a distance of 1700 AU from the disk centre. The accreting protostar is embedded inside a circumstellar disk and an envelope causing a visual extinction. This and its K-band magnitude argue in favour of an intermediate to high-mass object, equivalent to a spectral type of at least B4. For a main-sequence star, this would correspond to a stellar mass of 4 M."
How many new stars lay hidden inside? Far more than the famous Orion nebula may contain. So says a 2013 study produced by L. Eisa (et al):



"The complex resembles the Orion Nebula/KL region seen nearly edge-on: the bowl-shaped ionization blister is eroding the edge of the clumpy molecular cloud and triggering massive star formation, as evidenced by an ultra-compact HII region and luminous protostars. Only the most massive members of the young NGC 6618 stellar cluster exciting the nebula have been characterized, due to the comparatively high extinction. Near-infrared imagery and spectroscopy reveal an embedded cluster of about 100 stars earlier than B9. These studies did not cover the entire cluster, so even more early stars may be present. This is substantially richer than the Orion Nebula Cluster which has only 8 stars between O6 and B9."

History of Observation:

The Omega Nebula was first discovered by Philippe Loys de Cheseaux and is just one of the six nebulae in his documents. As he wrote of his discovery:



"Finally, another nebula, which has never been observed. It is of a completely different shape than the others: It has perfectly the form of a ray, or of the tail of a comet, of 7' length and 2' broadth; its sides are exactly parallel and rather well terminated, as are its two ends. Its middle is whiter than the border." Because De Cheseaux's work wasn't widely read, Charles Messier independently rediscovered it on June 3, 1764 and cataloged it in his own way: "In the same night, I have discovered at little distance of the cluster of stars of which I just have told, a train of light of five or six minutes of arc in extension, in the shape of a spindle, and in almost the same as that in the girdle of Andromeda; but of a very faint light, not containing any star; one can see two of them nearby which are telescopic and placed parallel to the Equator: in a good sky one perceives very well that nebula with an ordinary refractor of 3 feet and a half. I have determined its position in right ascension of 271d 45' 48", and its declination of 16d 14' 44" south."
By historical accounts, it was Sir William Herschel who may have truly had a little bit of insight on what this object might one day mean when he observed it on his own and reported:



"1783, July 31. A very singular nebula; it seems to be the link to join the nebula in Orion to others, for this is not without a possibility of being stars. I think a great deal more of light and a much higher power would be of service. 1784, June 22 (Sw. 231). A wonderful nebula. Very much extended, with a hook on the preceding [Western] side; the nebulosity of the milky kind; several stars visible in it, but they seem to have no connection with the nebula, which is far more distant. I saw it only through short intervals of flying clouds and haziness; but the extent of the light including the hook is above 10'. I suspect besides, that on the following [Eastern] side it goes on much farther and diffuses itself towards the north and south. It is not of equal brightness throughout and has one or more places where the milky nebulosity seems to degenerate into the resolvable [mottled] kind; such a one is that just following the hook towards the north. Should this be confirmed on a very fine night, it would bring on the step between these two nebulosities which is at present wanting, and would lead us to surmise that this nebula is a stupendous stratum of immensely distant fixed stars, some of whose branches come near enough to us to be visible as a resolvable nebulosity, while the rest runs on to so great a distance as only to appear under the milky form."
So where did the name "Omega Nebula" come from? That credit goes to John Herschel, who stated in his observing notes:



"The figure of this nebula is nearly that of the Greek capital Omega, somewhat distorted and very unequally bright. It is remarkable that this is the form usually attributed to the great nebula in Orion, though in that nebula I confess I can discern no resemblence whatever to the Greek letter. Messier perceived only the bright preceding branch of the nebula now in question, without any of the attached convolutions which were first noticed by my Father. The chief peculiarities which I have observed in it are, 1st, the resolvable knot in the following portion of the bright branch, which is in a considerable degree insulated from the surrounding nebula; strongly suggesting the idea of an absorption of nebulous matter; and 2ndly, the much feebler and smaller knot in the north preceding end of the same branch, where the nebula makes a sudden bend at an acute angle. With a view to a more exact representation of this curious nebula, I have at different times taken micrometrical measures of the relative places of the stars in and near it, by which, when laid down on the chart, its limits may be traced and identified, as I hope soon to have better opportunity to do than its low situation in this latitudes will permit."

Locating Messier 17:

Because M17 is both large and quite bright, its distinctive "2" shape isn't hard to make out in optics of any size. For binoculars and image correct finderscopes, try starting with the constellation of Aquila and begin tracing the stars down the eagle’s back to Lambda. When you reach that point, continue to extend the line through to Alpha Scuti, then southwards towards Gamma Scuti. M16 is slightly more than 2 degrees (about a fingerwidth) southwest of this star.



If you are in a dark sky location, you can also identify it easily in binoculars by starting at the M24 "Star Cloud", north of Lambda Sagittari (the teapot lid star), and simply scanning north. This nebula is bright enough to even cut through moderately light polluted skies with ease, but don't expect to see it when the Moon is nearby. You'll enjoy the rich starfields combined with an interesting nebula in binoculars, while telescopes will easily begin resolving the interior stars.



And here are the quick facts on M17 for your convenience:



Object Name: Messier 17

Alternative Designations: M17, NGC 6618, Omega, Swan, Horseshoe, or Lobster Nebula

Object Type: Open Star Cluster with Emission Nebula

Constellation: Sagittarius

Right Ascension: 18 : 20.8 (h:m)

Declination: -16 : 11 (deg:m)

Distance: 5.0 (kly)

Visual Brightness: 6.0 (mag)

Apparent Dimension: 11.0 (arc min)



And be sure to enjoy this video from the European Southern Observatory (ESO) that shows this nebula in all its glory:



https://youtu.be/YE5YEVU65pA



We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.



Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

The post Messier 17 (M17) – the Omega Nebula appeared first on Universe Today.