Het Astronomie Topic #6

quote:

Op woensdag 22 juni 2011 18:15 schreef ExperimentalFrentalMental het volgende:

[..]

Hoe kom je bij vloeistof? Er wordt gesproken over poreus stof

quote:

Op donderdag 23 juni 2011 09:05 schreef ExperimentalFrentalMental het volgende:

[..]

quote:

Op donderdag 30 juni 2011 09:05 schreef ExperimentalFrentalMental het volgende:
29-06-2011

De Nieuwe Wereld: UrtheCast

Google Earth op steroïden, noemen de makers het zelf. Of een kruising tussen Google Maps en Youtube. Waarmee het ook vergeleken mag worden: het UrtheCast-project zal voor velen de wereld veranderen. Iedereen zal via internet live-beelden vanuit het Ruimtestation ISS kunnen bewonderen. In HD kwaliteit dan nog wel. We zien gewoon wat de astronauten uit hun raampje kunnen aanschouwen. Voorheen moest je voor dergelijke plaatjes behoorlijk in de buidel tasten, maar binnenkort niet meer...

[ afbeelding ]

Dankzij een samenwerking met het Russische Ruimtevaartagentschap worden eind dit jaar de twee camera voor UrtheCast bevestigd. Door middel van online software zal iedereen kunnen inzoomen op elk gewenst plekje dat in de ooghoeken van de lens valt. Locaties zullen getagd kunnen worden, net zoals in Google Earth maar dan niet meer met foto's. Live, met een resolutie van één meter, wat toch behoorlijk goed is om mee te beginnen. Het is al mogelijk om een voetbalwedstrijd vanuit de lucht mee te volgen. Of gelijk welk ander evenement.

We kijken alvast uit naar het resultaat van dit project. De opties zijn erg divers. Wat dacht u van stiekem kijken in de tuin van buren en familie? Of naar dat besloten feestje in het openluchtzwembad van de plaatselijke swingersclub? En dan is er nog de mogelijkheid dat UFO's voor de les poseren. Wij popelen!

UrtheCast

(Grenswetenschap)

quote:

Op woensdag 22 juni 2011 21:47 schreef -CRASH- het volgende:

[..]

Poreus stof.... mmmmmm zal er wel bijzitten.
Maar mijn vermoeden gaat uit naar gesmolten ijs......
Die sporen is iig geen wind erosie. En ik zie o.a. zo geen grote rotsblokken liggen.

Maar eens afwachten wat de wetenschappers zeggen...
En als er vloeistof een onderdeel van de erosie is...
Dan claim ik de ontdekking

Helene (moon of Saturn): Cassini Flyby, June 2011

quote:

Op zaterdag 2 juli 2011 11:55 schreef Googolplexian het volgende:

Breathtaking New Images of the Moon

quote:

As the United States winds down its shuttle programme in a symbolic twist in a long-running space rivalry, Russia will gain complete control of access to the International Space Station.

The Russian space agency plays down any triumphalism, but US astronauts will remain dependent on Russia for access to the ISS at least until 2015 and will have to pay for seats in its Soyuz space capsules.

"We cannot say that we have won the space race, but simply that we have reached the end of a certain stage," the deputy head of the Russian space agency, Vitaly Davydov, said in an interview.

On July 8, four US astronauts will board the Atlantis shuttle for its last flight, wrapping up a three-decade-long programme in which the United States took turns to ferry supplies and crews to the ISS with Russia's Proton and Soyuz rockets.

Henceforth, Washington will have to pay $51 million per seat in Russia's space capsules until a new crew vehicle can be built by private companies, which US space agency NASA has estimated could be between 2015 and 2020.

Davydov of the space agency Roskosmos rejected any talk of rivalry, however, emphasizing that the ISS was primarily a story of successful international cooperation.

"I cannot think today of another international space project that is so effective in its scale, its significance and its results as the ISS," he said.

While Russia gains a symbolic victory, it will be a costly one, with the obligation to build more space ships to go back and forth to the ISS eating up a budget that could be spent on other projects.

Unlike the reusable NASA shuttles, the Russian Soyuz space capsules are single-use, except for the section in which spacemen return to Earth.

The situation is "not very convenient because it lays a heavy burden on Roskosmos's production capacities," space industry expert Igor Marinin told AFP.

Roskosmos this year declared its budget as $3 billion, a fraction of NASA's massive $18.5 billion budget.

And it has faced embarrassing setbacks, including the failure of several satellite launches that led to the sacking of the long-serving space chief Anatoly Perminov in April.

The country's space industry has also drawn smirks with a clunky experiment simulating a trip to Mars, in which volunteers are spending more than a year confined at a Moscow research institute and "landed" in a specially designed sand pit.

To recoup its costs, Roskosmos hopes to build a stronger presence in the commercial space market, such as satellite launches, its newly appointed chief Vladimir Popovkin said at the Saint Petersburg Economic Forum last month.

"The goal is to take up a suitable position in the commercial market: about 10 to 12 percent" of a market worth $300 billion per year, Popovkin said.

"This is one of the few things in our country that is competitive on the international level."

While Russia holds 40 percent of the world's space launches and constructs 20 percent of its space craft, currently "its share in the space business is unfairly small, not more than three percent," Popovkin said

Russia also faces new rivals, notably China, which in 2003 became the third country in the world after the Soviet Union and the United States to send a man into space in its own ship.

In ambitious plans, China hopes to put a robot on the Moon in 2013 and to build its own space station due to enter service in 2015.

Davydov acknowledged that China had become a rival, albeit still far behind, but said Russia did not feel threatened.

"There is a place for everyone in space," he said.

"In a certain sense, (China) is our competitor... but that is absolutely normal and we have not been afraid of the market for a long time now."

Ironically, the new commercial realities of the Russian space programme, with reduced budgets and the need to cooperate on large-scale projects, make some Soviet space veterans yearn for the competitive edge of the Cold War.

"It's strange that during the Cold War, when we cosmonauts and constructors dreamt of cooperation, there were a lot of new launches, but then cooperation came and now we are mostly repeating ourselves," lamented retired cosmonaut Georgy Grechko, 80.

The US space shuttle programme's goal of making launches less expensive was not ultimately reached, he said, and its end sees a return to single-use "sausage-like" rockets little different to those used 50 years ago.

"Mankind has lost its stimulus to go into space using more complicated machines," he complained.

quote:

^{Artist's conception of how the quasar would appear close up. The very hot extremely luminous quasar at the center of the image is very bright at ultraviolet wavelengths, and light from the quasar ionizes the surrounding gas, producing the red color that is characteristic of ionized hydrogen. Faint compact galaxies that have just been born appear in the background. The galaxies' hot stars also ionize their surroundings, but only in the immediate vicinity as they are far less luminous than the quasar which can ionize over a much larger volume. Image Credit: Gemini Observatory/AURA by Lynette Cook.}

An international team of astronomers have announced the discovery of the most distant known supermassive black hole, seen as a luminous quasar [1] caused by gas falling into the black hole.

The discovery came to light using data from an ongoing infrared sky survey being conducted at the United Kingdom Infrared Telescope (UKIRT) and critical follow-up confirmation observations with the Gemini North telescope, both on Mauna Kea in Hawai'i. The results are presented in the June 30, 2011 issue of the Journal Nature [2].

The light from the quasar started its journey toward us when the universe was only 6% of its present age, a mere 770 million years after the Big Bang, at a redshift of about 7.1 [3]. "This gives astronomers a headache," says lead author Daniel Mortlock, from Imperial College London.

"It's difficult to understand how a black hole a billion times more massive than the Sun can have grown so early in the history of the universe. It's like rolling a snowball down the hill and suddenly you find that it's 20 feet across!"

However, as well as being a headache, the new quasar is a great opportunity, because it allows scientists to measure the conditions in the gas that the quasar's light passes through on its way to us. "What is particularly important about this source is how bright it is," says Mortlock. "It's hundreds of times brighter than anything else yet discovered at such a great distance. This means that we can use it to tell us for the first time what conditions were like in the early universe."

Cosmologists are extremely keen to measure the state of gas in the early universe, to understand the process of how stars and galaxies formed. Most of the gas in the universe is hydrogen, and most of it is ionized at the present time, meaning that the electrons have been stripped off the protons. As one looks further away and thus further back in time, one should eventually reach the time when the gas was neutral, with the electrons and protons combined as atoms, before most of the stars in the universe have formed, over 12 billion years ago.

The transition between these periods is the epoch of reionization, a milestone in cosmic history. The light from the new quasar displays the characteristic signature of neutral gas. This signature, showing the quasar is beyond the epoch of reionization, was predicted in 1998 but has never been observed before.

"Being able to analyze matter at this critical juncture in the history of the universe is something we've been long striving for but never quite achieved. Now it looks like we have crossed the barrier with this observation," said Prof. Steve Warren, leader of the quasar team. "It's like discovering a new continent which we can now explore."

The quasar, named ULAS J1120+0641, was discovered in the UKIRT Infrared Deep Sky Survey (UKIDSS) a new map of the sky at infrared wavelengths. Such very distant, highly redshifted objects are much more easily found in infrared light [4].

"It was for just this sort of discovery that we began this ambitious survey in 2005," said Prof. Gary Davis, Director of UKIRT. To find the quasar the team sifted through images of over 10 million sources. "We'd been searching for five years, and hadn't found anything, and were beginning to lose heart," said Warren. "It gave us a terrific jolt when we found it as we hadn't really expected to discover anything quite so far away."

To confirm that the object was really a distant quasar and measure its distance, in December 2010 the team made further observations with the 8-meter Gemini North telescope, UKIRT's neighbor on Mauna Kea, using the Gemini Near-Infrared Spectrograph (GNIRS). "The timing was perfect..." recalled Kathy Roth, an astronomer at Gemini Observatory, "...as we got the observation request just days after the spectrograph had been made available for science use at Gemini North. Once the measurements were made it became immediately obvious they had found what they were looking for."

The team then quickly collected an additional set of detailed observations, with telescopes at the European Southern Observatory (ESO), and in the Canary Islands [5]. Collectively, these observations from many facilities allowed a detailed study of the properties of the quasar itself, and of the surrounding gas.

The team plans further detailed observations of ULAS J1120+0641, but also hope to find more such distant but bright quasars. "There may be 100 such objects spread around the whole sky," says Mortlock, "but finding them amongst the billions of other objects in astronomical images is a serious challenge!"

[1] Quasars are the most luminous objects known. They are thought to be the result of gas in a swirling disk accreting onto a supermassive black hole sitting at the center of a distant galaxy - as the gas falls in it gets extremely hot and emits radiation. The black hole slowly grows as it "swallows" more gas. At 770 million years after the Big Bang, there is barely enough time for a black hole to grow to two billion solar masses even if it is swallowing gas at the maximum possible (theoretical) rate.

[2] Details of the discovery are published in a paper in Nature on June 30th, entitled 'A luminous quasar at a redshift of z=7.085' by D.J. Mortlock, S. J. Warren, B. P. Venemans, M. Patel, P. C. Hewett, R. G. McMahon, C. Simpson et al.

[3] The UKIRT Infrared Deep Sky Survey [UKIDSS] is a project to map a large area of sky in infrared light, to much fainter light levels than attempted before. The new quasar ULAS J1120+0641 comes from a component called the "Large Area Survey (LAS)." The prefix J and the numbers refer to the quasar's position on the sky. The survey uses a very large infrared camera called Wide Field Camera (WFCAM) which was built at the Astronomy Technology Center (ATC) at the Royal Observatory Edinburgh. The observations are made at the United Kingdom Infrared Telescope (UKIRT) on the summit area of Mauna Kea in Hawai'i. Both the ATC and UKIRT are establishments of the UK's Science and Technology Facilities Council (STFC).

[4] Light from distant parts of the universe is stretched out or "redshifted" by the expansion of the universe. This means that light which starts out at the quasar as ultraviolet and visible light arrives at Earth as infrared light. The light from ULAS J1120+0641 is stretched by a factor of 7.1. Because light travels at a finite speed, the light we see now from ULAS J1120+0641 started out about 12.9 billion years ago. The universe is currently thought to be about 13.7 billion years old, so we see ULAS J1120+0641 as it was 0.8 billion years after the universe began, or 770 million years.

[5] http://www.eso.org/public/news/eso1122/