Kako astronauti idu u WC u svemiru? :D :D

<< < (2/20) > >>

Meho Krljic:
New Comet Discovered—May Become "One of Brightest in History" 

--- Quote ---
 Next year comet 2012 S1 might outshine the moon. 
Andrew Fazekas
for National Geographic News
Published September 27, 2012
  If astronomers' early predictions hold true, the holidays next year may hold a glowing gift for stargazers—a superbright comet, just discovered streaking near Saturn.
Even with powerful telescopes, comet 2012 S1 (ISON) is now just a faint glow in the constellation Cancer. But the ball of ice and rocks might become visible to the naked eye for a few months in late 2013 and early 2014—perhaps outshining the moon, astronomers say.
The comet is already remarkably bright, given how far it is from the sun, astronomer Raminder Singh Samra said. What's more, 2012 S1 seems to be following the path of the Great Comet of 1680, considered one of the most spectacular ever seen from Earth.
"If it lives up to expectations, this comet may be one of the brightest in history," said Samra, of the H.R. MacMillan Space Centre in Vancouver, Canada.
So what makes a comet a showstopper? A lot depends on how much gas and dust is blasted off the central core of ice and rocks. The bigger the resulting cloud and tail, the more reflective the body may be.

Because 2012 S1 appears to be fairly large—possibly approaching two miles (three kilometers) wide—and will fly very close to the sun, astronomers have calculated that the comet may shine brighter, though not bigger, than the full moon in the evening sky.
(Also see "New Comet Found; May Be Visible From Earth in 2013.")
Refugee From the Edge of the Solar System?
First spotted late last week by Russian astronomers Artyom Novichonok and Vitali Nevski of the International Scientific Optical Network (ISON), comet 2012 S1 was confirmed by the International Astronomical Union on Monday.
But while we know what 2012 S1 is, it's still unclear where it came from. Its orbit suggests the comet may be a runaway from the Oort cloud, where billions of comets orbit about a hundred thousand times farther from the sun than Earth is.
"For astronomers, these distant origins are exciting," Samra said, "because it allows us to study one of the oldest objects in the solar system still in its original, pristine condition."
(Related: "Comet Is Cosmic Snow Globe, NASA Flyby Shows.")
New Comet Bound for Glory?
Right now, 2012 S1 appears to be about 615 million miles (990 million kilometers) from Earth, between the orbits of Saturn and Jupiter, astronomers say.
As the sun's gravity pulls the comet closer, it should pass about 6.2 million miles (10 million kilometers) from Mars—possibly a unique photo opportunity for NASA's new Curiosity rover.
Current orbital predictions indicate the comet will look brightest to us in the weeks just after its closest approach to the sun, on November 28, 2013—if 2012 S1 survives the experience.
As the comet comes within about 1.2 million miles (2 million kilometers) of the sun, the star's intense heat and gravity could cause the ice and rubble to break apart, scotching the sky show. (Related: "Comet Seen Vaporizing in Sun's Atmosphere—A First.")
"While some predictions suggest it may become as bright as the full moon, and even visible during the day, one should be cautious when predicting how exciting a comet may get," Samra said.
"Some comets have been notorious for creating a buzz but failing to put on a dazzling display," he said. "Only time will tell."
More: See the first pictures of a peanut-like comet >> 

--- End quote ---

Meho Krljic:
I malo o crnoj rupi u središtu galaksije M87, ma koja to bila...
 A Spinning Black Hole at a Galaxy's Center 

--- Quote ---
  Like all invisible things that are only partly understood, black holes evoke a sense of mystery. Astronomers know that the tremendous gravitational pull of a black hole sucks matter in. They also know that the material falling in causes powerful jets of particles to shoot out of the black hole at nearly the speed of light. But how exactly this phenomenon occurs remains a matter of conjecture, because astronomers have never quite managed to observe the details.
Well, now they have. Sheperd Doeleman, an astrophysicist at the Massachusetts Institute of Technology Haystack Observatory in Westford, and his colleagues have taken the closest look to date at the region where matter swirls around a black hole. By measuring the size of the base of a jet shooting out of the supermassive black hole at the center of the M87 galaxy, the researchers conclude that the black hole must be spinning and that the material orbiting must also be swirling in the same direction. Some of the material from this orbiting "accretion disk" is also falling into the black hole, like water swirling down a drain. The finding appears online today in Science.
For the past few years, Doeleman and his colleagues have been working to link up radio dishes around the world into a virtual telescope with unprecedented magnifying power, which would enable researchers to observe the immediate vicinity of the black hole in the heart of M87—a favorite target for astronomers, as it is one of the brightest objects in the sky. So far, the researchers have linked radio dishes at three sites. That hasn't provided enough resolution to see all the way to the edge of the black hole. But it enabled the researchers to measure the area through which the jet is being emitted.
The size of this emission region fits with only one particular theoretical model of how these jets form. The base of the jet "reduces to the size we measured only when the black hole is spinning and the accretion disk is orbiting in the same direction," Doeleman says. "What we find so exciting is that we are now finally able to measure structures so close to the black hole." He and his colleagues hope to use the Event Horizon Telescope—the instrument being created by linking the radio dishes—to test "whether Einstein's theory of general relativity is valid at the one place in the universe where it might break down: the event horizon of a black hole."
The paper "is very interesting," says Meg Urry, an astrophysicist at Yale University who was not involved in the study. "Measuring the launch point for the jet is absolutely critical for understanding how jets form, and indeed how jet energy is extracted from the black hole-disk system." However, Urry points out, the conclusions rest on a number of assumptions that are "difficult to confirm"—such as whether the measured area does lie directly on top of the black hole rather than off to the side or elsewhere.   

--- End quote ---

Meho Krljic:

--- Quote ---
This fall, Creative Time will launch The Last Pictures, an archival disc created by artist Trevor Paglen, into outer space, where it will orbit the earth for billions of years affixed to the exterior of the communications satellite EchoStar XVI. To create the artifact, Paglen micro-etched one hundred photographs selected to represent modern human history onto a silicon disc encased in a gold-plated shell, designed at the Massachusetts Institute of Technology (MIT) and Carleton College.

The complete set of one hundred images can be found in The Last Pictures book, co-published by Creative Time Books and University of California Press, available for purchase in bookstores nationwide and online.

--- End quote ---

Vanzemaljci će, bojim se, umreti od smeha što nismo razvili tehnologiju kolor fotografije  :lol:

Meho Krljic:
Kreće dvogodišnji projekat potrage za Dajsonovim sferama:
The Best Way to Find Aliens: Look for Their Solar Power Plants

--- Quote ---A team of astronomers is now looking for Dyson Spheres, massive star-scale solar power plants that extraterrestrial hunters hope alien civilizations employ.
In 1960, mathematician, physicist, and all-around genius Freeman Dyson predicted that every civilization in the Universe eventually runs out of energy on its home planet, provided it survives long enough to do so. Dyson argued that this event constitutes a major hurdle in a civilization's evolution, and that all those who leap over it do so in precisely the same way: they build a massive collector of starlight, a shell of solar panels to surround their home star. Astronomers have taken to calling these theoretical megastructures Dyson Spheres. Dyson's insight may seem like nothing more than a thought experiment, but if his hypothesis is sound, it has a striking implication: if you want to find advanced alien civilizations, you should look for signs of Dyson Spheres.
Last month a trio of astronomers led by Penn State's Jason Wright began a two-year search for Dyson Spheres, a search that will span the Milky Way, along with millions of other galaxies. Their project was just awarded a sizable grant from the Templeton Foundation, a philanthropic organization that funds research on the "big questions" that face humanity, questions relating to "human purpose and ultimate reality."
So how do Wright and his team aim to find a Dyson Sphere? Though the word "sphere" summons to mind a solid structure, Wright says his team won't be looking for solid shells. "Even though there is enough mass in our solar system to construct a solid sphere, such a structure would not be mechanically feasible," Wright told me. "It would probably have to be more like a swarm of collectors."
This wild speculation about futuristic alien tech probably seems unscientific, but the search for extraterrestrial civilizations has always depended upon such speculation. Think of all the predictions that are baked into SETI, the Search for Extraterrestrial Intelligence, which uses telescope arrays to scan the heavens for alien radio communications. At present, humans have nowhere near the excess energy you'd need to send the kind of radio signal that SETI is looking for. Earlier this year, astronomer Robert Gray told me that "to operate a radio beacon that is on all the time, broadcasting in all directions, strong enough to be picked up from many light years away, you need an enormous amount of energy -- something in the range of thousands and thousands of big power plants." SETI is betting that advanced civilizations will value communicating with other civilizations a lot, or at least enough to justify huge energy expenditures. It's also betting that such civilizations will communicate via radio waves, and that they will transmit their signals on one of the frequencies that we monitor. For us to find intelligent extraterrestrials, it's not enough that they exist; they have to develop and use technology in predictable ways.
Compared with SETI, a search for Dyson Spheres assumes a lot less about the goals of futuristic alien civilizations. In fact, most of its assumptions proceed directly from simple biology. As Wright, the project leader, explained to me, "life, by definition, uses energy, which it must reradiate as waste heat." The larger the civilization, the more energy it uses and the more heat it reradiates. Life also (by definition) reproduces, which introduces the possibility of exponentially increasing energy demands. If left unchecked, those increases will eventually outstrip the available energy on a planet. That would leave a growing civilization no choice but to mine energy from other planets and, eventually, their stars.
Let's use the Earth as a test case. As Oliver Morton has pointed out with a lovely metaphor, the sun beams a total of 120,000 terawatts per day onto our planet. That's 10,000 times the amount that flows through our industrial civilization. That's a lot of energy, but remember that our industrial civilization is young, and growing fast. In just the past 30 years, we've doubled our global energy supply. At that doubling rate, in 400 years we will be collecting or generating enough energy to match the total sunlight that comes to our planet. At that point, it may be time to draw up plans for a Dyson Sphere.
It's conceivable that an advanced alien civilization could be exponentially more energy-intensive than ours, especially when you consider that its industrial revolutions and energy doublings may have begun billions of years ago. Dyson Spheres could be an ancient and prolific phenomenon in our universe.

An artist's rendering of the "swarm" model of Dyson Sphere. (Wikimedia Commons)
Dyson Spheres also fit squarely within with another theoretical model of civilizational advancement: the Kardashev Scale. In 1964, Soviet astronomer Nikolai Kardashev tried to plot out a theory of technological advancement based on a civilization's mastery of larger and larger energy sources over time. Under the Kardashev Scale, a Type I civilization uses all of the energy available on its home planet, a Type II civilization uses all of the energy from its local star, and a Type III civilization makes use of all the energy in its galaxy. The search for Dyson Spheres is, in essence, a search for Type II civilizations. And because it is premised on a civilization's energy usage, it has another advantage over efforts like SETI's: It allows us to find aliens that aren't necessarily interested in talking to us.
That's because if Dyson Spheres exist, they promise to give off a very particular kind of heat signature, a signature that we should be able to see through our infrared telescopes. The solar energy collected by a Dyson Sphere would heat it, the same way that your computer heats up when it uses electricity. That heat would radiate off the sphere as infrared light rather than visible light. "A Dyson Sphere would appear very bright in the mid-infrared," Wright explained to me. "Just like your body, which is invisible in the dark, but shines brightly in mid-infrared goggles."
A civilization that built a Dyson Sphere would have to go to great lengths to avoid detection, either by getting rid of its waste heat in some novel way, or by building massive radiators that give off heat so cool that it would be undetectable against the cosmic microwave background, the faint afterglow of the Big Bang. Wright told me that the latter solution would involve building a sphere that was a hundred times larger than necessary. "If a civilization wants to hide, it's certainly possible to hide," he said, "but it requires massive amounts of deliberate engineering across an entire civilization."
Wright's project won't be the first search for Dyson Spheres. In the 1980's, researchers at Fermilab looked for Dyson Sphere signatures in the data generated by IRAS, the first ever space-based infrared survey of the sky. They found several candidate sources, but on closer inspection they turned out to be giant stars, or else dusty objects that absorb starlight and then reradiate it.
Wright's group will have access to data that Fermilab's researchers could only dream of. They'll be scanning three different infrared sky surveys, including NASA's Wide-field Infrared Survey Explorer (WISE) (pictured up top) which is hundreds of times more sensitive than IRAS. They'll be looking for Dyson Spheres in our galaxy, but also for whole galaxies with excess waste heat -- galaxies that may contain a large number of stars enshrouded in technological megastructures.
If Wright and his team find something outside the range of expected astronomical phenomena, a lengthy confirmation process will begin, a process that will likely involve astronomers and telescopes across the world. Wright was careful to note that no matter what the initial data indicates, he won't be jumping to any conclusions. "More than once some inexplicable object has been discovered that looked like aliens, and then slowly it became clear that it was a very interesting, but totally natural, phenomenon," he said. Indeed, Nikolai Kardashev once thought he'd identified several good candidates for Type III civilizations, which operate on a galactic scale. But in the end, they turned out to be quasars.
Near the end of our conversation, I asked Wright if Dyson Spheres and the Kardashev scale had any competitors, if there were other theoretical models that described what extraterrestrial civilizations might look like. "I'm not aware of any other scales in the refereed scientific literature," he said, "but there probably are some." In astrobiology, the line between science and science fiction is blurry. "Often the best discussions of these issues are in paperback novels," Wright noted. "I can tell you, it's strange to write a serious research proposal and have half of your bibliography be science fiction."
--- End quote ---

Meho Krljic:
Ima na Devedesetdvojci, ali evo ovde live stream Baumgartnerovog skoka sa 36 kilometara:


[0] Message Index

[#] Next page

[*] Previous page

Go to full version