Het Astronomie Topic #6

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

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

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

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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)

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

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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

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

Breathtaking New Images of the Moon

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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.

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^{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/

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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)

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Op dinsdag 12 juli 2011 08:55 schreef ExperimentalFrentalMental het volgende:
12-07-2011

Neptunus viert 1e 'verjaardag' sinds ontdekking in 1846

[ afbeelding ]

De planeet Neptunus is jarig. Op dinsdag 12 juli is de planeet precies één keer rond de zon gedraaid sinds hij in 1846 ontdekt werd. Dat meldt de Volkssterrenwacht Mira.

"Op 12 juli 2011 bereikt de planeet Neptunus een positie aan de hemel die overeenkomt met de positie waar de planeet zich bevond toen die tijdens de nacht van 23 op 24 september 1846 door de Duitse astronoom Johann Galle samen met zijn assistent Heinrich d'Arrest van op de sterrenwacht van Berlijn werd ontdekt", stelt de Volkssterrenwacht in een bericht op zijn website.

Neptunus is de verste planeet van het zonnestelsel. Hij heeft 164,79 aardse jaren nodig om een volledige baan rond de zon te beschrijven. (belga/jv)

(HLN)

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Op woensdag 13 juli 2011 08:51 schreef ExperimentalFrentalMental het volgende:
11-07-2011

'Donker vuurwerk' op de zon

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Bij een zonsuitbarsting op 7 juni jongstleden werden kolossale wolken van relatief koel plasma de ruimte in geblazen, die vervolgens onder invloed van het zwaartekrachtsveld van de zon terugvielen naar het oppervlak, en daar weer voor nieuwe, kleinere uitbarstingen zorgden. De relatief koele gaswolken, met afmetingen ter grootte van complete planeten, steken donker af tegen het heldere zonsoppervlak op filmpjes die gemaakt zijn door het Amerikaanse Solar Dynamics Observatory.

Bij de uitbarsting werd ook een geweldige hoeveelheid zonnegas het zonnestelsel in geblazen (ongeveer 4,5 miljard ton), in een van de grootste coronale massa-ejecties die ooit zijn waargenomen.

Hoewel de zonsuitbarsting niet extreem veel röntgenstraling produceerde (het ging om een klasse M-vlam, voor 'medium'), is een dergelijk 'donker vuurwerk' nooit eerder zo spectaculair vastgelegd, aldus zonnefysici van NASA's Goddard Space Flight Center.

© Govert Schilling

• Filmpje 1 (13 MB)
• Filmpje 2 (99 MB)

(allesoversterrenkunde)

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_{Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square meter, W/m2) of 100 to 800 picometer X-rays near Earth, as measured on the GOES spacecraft.}

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The Milky Way so close you can almost taste it: Breath-taking snaps of galaxy seen with the naked eye

A star-gazer has come a little bit closer to the final frontier - after spending 18 months photographing the night sky.

With just an ordinary digital camera, Alex Cherney turned thousands of snaps into an incredible time-lapse video of the cosmos.
Using long exposures to allow more light in, these breath-taking pictures from the southern tip of Australia demonstrate how he captured the dramatic way the sky changes at night.

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NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 9, 2011. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA


PASADENA, Calif. -- On July 15, NASA's Dawn spacecraft will begin a prolonged encounter with the asteroid Vesta, making the mission the first to enter orbit around a main-belt asteroid.

The main asteroid belt lies between the orbits of Mars and Jupiter. Dawn will study Vesta for one year, and observations will help scientists understand the earliest chapter of our solar system's history.

As the spacecraft approaches Vesta, surface details are coming into focus, as seen in a recent image taken from a distance of about 26,000 miles (41,000 kilometers). The image is available at: http://www.nasa.gov/missi(...)wn-image-070911.html .

Engineers expect the spacecraft to be captured into orbit at approximately 10 p.m. PDT Friday, July 15 (1 a.m. EDT Saturday, July 16). They expect to hear from the spacecraft and confirm that it performed as planned during a scheduled communications pass that starts at approximately 11:30 p.m. PDT on Saturday, July 16 (2:30 a.m. EDT Sunday, July 17). When Vesta captures Dawn into its orbit, engineers estimate there will be approximately 9,900 miles (16,000 kilometers) between them. At that point, the spacecraft and asteroid will be approximately 117 million miles (188 million kilometers) from Earth.

"It has taken nearly four years to get to this point," said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our latest tests and check-outs show that Dawn is right on target and performing normally."

Engineers have been subtly shaping Dawn's trajectory for years to match Vesta's orbit around the sun. Unlike other missions, where dramatic propulsive burns put spacecraft into orbit around a planet, Dawn will ease up next to Vesta. Then the asteroid's gravity will capture the spacecraft into orbit. However, until Dawn nears Vesta and makes accurate measurements, the asteroid's mass and gravity will only be estimates. So the Dawn team will need a few days to refine the exact moment of orbit capture.

Launched in September 2007, Dawn will depart for its second destination, the dwarf planet Ceres, in July 2012. The spacecraft will be the first to orbit two solar system destinations beyond Earth.

Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission team.

For a current image of Vesta and more information about the Dawn mission, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov .You also can follow the mission on Twitter at: http://www.twitter.com/nasa_dawn .

Priscilla Vega/Jia-Rui Cook 626-298-3290/818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
priscilla.r.vega@jpl.nasa.gov / jccook@jpl.nasa.gov

Dwayne C. Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

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Milky Way’s Core Hides Big Twisted Ribbon

A space telescope peering into the Milky Way galaxy’s dusty core has spied a colossal twisted ribbon of supercooled material.

Astronomers previously studied gas-piercing infrared images of the Milky Way’s cloudy barred core, but they didn’t have photos with resolution high enough to discern the ribbon’s entire structure. Molinari and others found the ring by aiming the European Space Agency’s infrared Herschel Space Observatory toward galactic center.

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Astronomen hebben met behulp van de Hubble-telescoop een vierde maan rondom de dwergplaneet Pluto ontdekt.

De maan is heel klein en heeft voorlopig de naam P4 gekregen. De astronomen stuitten op de maan toen ze op zoek waren naar ringen rondom Pluto.

Kleintje
P4 is de kleinste maan rondom Pluto met een diameter tussen de dertien en 34 kilometer. Dat is heel wat kleiner dan Pluto’s grootste maan, Charon. Deze heeft een diameter van meer dan 1000 kilometer. De nieuwe maan bevindt zich tussen de banen van Nix en Hydra, de twee manen die Hubble in 2005 ontdekte.
Helder
De astronomen zijn verbaasd over de ontdekking van de maan. “Ik vind het opmerkelijk dat de camera’s van Hubble ons in staat stelden om zo’n klein object vanaf een afstand van meer dan vijf miljard kilometer zo helder waar te nemen,” merkt onderzoeker Mark Showalter op.

“Dit is een fantastische ontdekking,” vindt onderzoeker Alan Stern. “Nu we weten dat zich in het systeem van Pluto nog een maan bevindt, kunnen we observaties van dichtbij gaan inplannen tijdens een fly-by.”

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Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy dwarf planet Pluto. The tiny, new satellite – temporarily designated P4 -- was uncovered in a Hubble survey searching for rings around the dwarf planet.

The new moon is the smallest discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 km).

"I find it remarkable that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in Mountain View, Calif., who led this observing program with Hubble.

The finding is a result of ongoing work to support NASA's New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable to planning for New Horizons' close encounter.

"This is a fantastic discovery," said New Horizons’ principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colo. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby."

The new moon is located between the orbits of Nix and Hydra, which Hubble discovered in 2005. Charon was discovered in 1978 at the U.S. Naval Observatory and first resolved using Hubble in 1990 as a separate body from Pluto.

Lunar rocks returned to Earth from the Apollo missions led to the theory that our moon was the result of a similar collision between Earth and a Mars-sized body 4.4 billion years ago. Scientists believe material blasted off Pluto's moons by micrometeoroid impacts may form rings around the dwarf planet, but the Hubble photographs have not detected any so far.

"This surprising observation is a powerful reminder of Hubble's ability as a general purpose astronomical observatory to make astounding, unintended discoveries," said Jon Morse, astrophysics division director at NASA Headquarters in Washington.

P4 was first seen in a photo taken with Hubble's Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. The moon was not seen in earlier Hubble images because the exposure times were shorter. There is a chance it appeared as a very faint smudge in 2006 images, but was overlooked because it was obscured.

Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

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Op dinsdag 19 juli 2011 08:43 schreef ExperimentalFrentalMental het volgende:

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18-07-2011

Eerste close-up van planetoïde Vesta gepresenteerd

[ afbeelding ]

NASA-ruimtesonde Dawn heeft de eerste gedetailleerde opname van de grote planetoïde Vesta naar de aarde gezonden. Dawn draait sinds afgelopen zaterdag Dawn op een afstand van ongeveer 15.000 kilometer om de planetoïde.

De eerste close-up toont de zuidkant van Vesta, waar ongeveer een miljard jaar geleden een kleinere planetoïde is ingeslagen. De krater die daarbij is ontstaan, is bijna zo breed als de planetoïde zelf. Het gebied wordt gekenmerkt door talrijke groeven en kleinere inslagkraters van latere datum.

Het echte onderzoek aan Vesta, dat bijna een jaar gaat duren, begint in augustus. De komende drie weken zal Dawn in een lagere omloopbaan worden gemanoeuvreerd, zodat het oppervlak van de planetoïde nog nauwkeuriger kan worden bestudeerd.

© Eddy Echternach (www.astronieuws.nl)

(allesoverserrenkunde)

A year in the life of the moon

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Created by a team at the Goddard Space Flight Center's Scientific Visualisation Studio, it's the first time a computer simulation has reproduced the shadows on the moon in such high resolution. They were reconstructed using elevation measurements taken by the Lunar Orbiter Laser Altimeter (LOLA) from the Lunar Reconnaissance Orbiter (LRO), which has already captured more detailed data than all previous missions combined.

The video depicts a typical view from the northern hemisphere. The most dramatic monthly change is the moon's phase, caused by the shifting angle of the sun as the moon orbits the Earth. However the time-lapse also takes into account the slightly different face visible from the same point over time. Due to the tilt and shape of the moon's orbit, we see it from a slightly different angle over the course of a month. This generates a slight wobble when the views are compressed together.

Magnetic rope triggers solar storms

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If a solar storm is directed towards Earth, it can wreak havoc on satellite communications and even disrupt electricity power grids. What causes this space weather has remained a mystery but now Jie Zhang and his team from George Mason University in Virginia have found that a phenomenon called a giant magnetic rope can trigger an eruption.

The discovery was made thanks to images of the sun captured by NASA's Solar Dynamic Observatory (SDO) spacecraft, which are snapped every 10 seconds. The pictures revealed a superhot channel forming through an active region before a storm. The team thinks this is a magnetic rope: a network of magnetic field lines wrapped around a central axis. The winding creates a strong electric current that can power the rope to move outwards.

According to Zhang, understanding the process will help us better predict these storms. "We cannot prevent solar storms, just like we cannot prevent earthquakes or volcanoes," he says. "But the development of prediction capacity can help mitigate adverse effects. For instance, satellite operators can power down systems to prevent possible damage."

ScienceCasts: Summer Meteor Shower

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Op maandag 1 augustus 2011 21:40 schreef -CRASH- het volgende:
[ afbeelding ]
...

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Last week, this video of a mysterious bubble expanding in space was captured by a webcam outside the Canada-France-Hawaii Telescope (CFHT), an astronomical observatory in Hawaii. It generated a lot of discussion on astronomy forums, where people have been speculating on what it might be. A few commenters suggested it was linked to a recent missile launch and now we can confirm that it is indeed exhaust from the launch.

Mysterious halo of light

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Op zaterdag 6 augustus 2011 14:34 schreef Googolplexian het volgende:

Vesta Rotation Movie — August 2011

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Op dinsdag 9 augustus 2011 09:17 schreef ExperimentalFrentalMental het volgende:

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Misschien een goed idee om het filmpje ook hier te plaatsen?
MARS - De Missies! Deel 7

A flyby of Amalthea

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An experimental computer generated animation showing a flyby of Jupiter's small satellite Amalthea. The individual frames were rendered using specialized software written by myself. While the small scale features on Amalthea's surface are fictional the large scale features and Amalthea's overall shape should be fairly accurate.

Mimas' big Herschel crater

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An experimental animation showing a flight over the big Herschel crater on Saturn's satellite Mimas. The Mimas digital elevation model should be fairly realistic. It was created using stereo imagery and shape from shading using images obtained by NASA's Cassini spacecraft as source data. Only the smallest craters are fictional.

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An Atmosphere for the Moon
^{N. M. Hoekzema}



A thin, semi-stable lunar atmosphere may form within a few centuries. This atmosphere, probably dominated by oxygen, may have a total mass in the order of 10¹¹ kg and a surface pressure of order of 10^-2 Pa: i.e., comparable to Earth’s atmosphere at an altitude of about 100 km.

It may be feasible to install a thick, moist lunar atmosphere. However, it is at least doubtful whether this can result in the Terra-formation of the Moon in the foreseeable future.


Introduction

The present extremely thin lunar atmosphere is completely dominated by the solar wind; it contains only about 10⁴--10⁵ kg of hydrogen, and helium, and a small percentage of heavier gases: mainly oxygen, carbon, and nitrogen. If compressed to a pressure of one Barr, this whole atmosphere would fit into a single large Zeppelin. Most of its particles are captured from the solar wind, but part of the oxygen is extracted from the lunar soil by impacts with: energetic photons, solar wind particles, cosmic rays, or (micro) meteorites. The average atmospheric particle is an ion, traveling around in semi-ballistic orbits, and resides in this atmosphere for only a few weeks, before binding with the soil, or being kicked into space by solar wind interactions.

I’ll mention two possible scenarios for the human future and discuss their impact on the lunar atmosphere. The last section deals with speculations about whether it is possible to Terra-form the Moon.


Humans Altering Atmospheres

Humans have significantly altered the Earth atmosphere; e.g., in the past century it has been 'enriched' with 10¹⁴--10¹⁵ kg of carbon dioxide, causing the popular concern about the greenhouse effect. In the recent past humans substantially altered the lunar atmosphere as well; exhaust gases from the Apollo landing and ascend vehicles temporarily thickened it by more then 10%. But these effects were very temporal and within a few months the extra lunar atmosphere had almost completely disappeared through interactions with the solar wind.

But what if the human involvement with the Moon were more substantial? If there were ever to be substantial industries on the Moon, what would their impact be on the local atmosphere? To formulate an answer we must consider the possible nature of such industries.

Creating them would consume at least hundreds of billions, and more probably a few trillion dollars. It is utterly naive to think that humans would ever make such a huge investment without the certainty of a solid yield that could not be obtained from Earth based industries. Right now I can only think of two slightly plausible scenarios that might initiate extensive lunar settlement in the foreseeable future, together with industries that are important in this respect.

1. Controlled nuclear fusion will finally be mastered and the supply of ³₂He for fusion reactors will depend on mining the Moon.

2. Humanity runs out of fossil fuels and it turns out to make economic sense to build large Earth orbiting solar power satellites, creating the need for large quantities of lunar ores to construct them.

Traveling to the Moon is very expensive, but humanity spends about ten trillion dollars per year to pay for its energy bills, people could easily afford to mine the Moon if it were important for generating a major part of the worlds energy supply.


Mining Lunar ³₂He

Future nuclear fusion plants will depend on either ³₁H (tritium) or ³₂He. There is no significant natural source for tritium and the cost of manufacturing it could be prohibitive. Its use in fusion generators would generate much radioactive junk making it a less than ideal fuel.

³₂He is a much cleaner fuel, but also not readily available. Though the isotope is stable, it is only present on Earth in extremely minute quantities. Almost all of the helium on Earth originates from alpha decay of natural radioactive isotopes and such decay does not produce ³₂He.

Through the ages about 10¹⁵ kg of solar wind particles got stuck in the upper few centimeters of the lunar surface. Most of the captured gases, including about 5% helium, escape when the soil is only slightly heated. Though the lunar resources of helium are smaller than that of Earth, they have a solar origin and therefore contain a much larger fraction of the required isotope; the surface of the Moon contains a few kilograms of ³₂He per square kilometer. If were required in large quantities today, it would be cheaper to collect it on the Moon than to manufacture it artificially.
About 100 tons ³₂He per year could cover the worlds demand for energy; harvesting it on the Moon would not only yield the required isotope, but could free the other one million times more abundant gases as well.

Mining Lunar Ores

Once the readily available resources of fossil fuels on Earth are exhausted the Sun may become the main source of energy for humanity. In the late seventies it was calculated that solar power becomes cheaper than fossil energy once the oil price rises above
$70 per barrel (recent years: near $20). At present, placing solar power satellites in Earth orbit would be more efficient than building large scale solar power plants on Earth. In space there are no clouds obscuring the sun, there is no night, the station can always be directed ideally, and there is little weathering that limits the expected lifespan of such installations. Moreover, space is not as crowded as Earth. On Earth it would not be easy to free an area that is several times as large as the surface of the Netherlands, for solar power plants.

When building large orbiting solar power satellites, it would be ludicrous to blast all constructing materials up from Earth by rocket. The Moon offers them all, and they can be shipped up from the lunar surface fairly easily with electro-magnetic guns. The building of large solar power satellites thus induces the development of substantial lunar industries of which a blast furnace would probably have the largest impact on the lunar atmosphere.

To set the magnitude of such industries: Hoogovens, the Dutch Steel-Works, produced about 6.10⁹ kg of steel in 1994. On the Moon a production facility this size would set free 10⁹--10¹⁰ kg of oxygen per year.


Thickening the Lunar Atmosphere

It is possible that within one century Lunar based industries will dump much gas into the lunar environment. The oxygen output from a substantial mining industry could exceed 10⁹--10¹⁰ kg per year. If a fusion industry becomes important, the output from a ³₂He mining industry could add up to 10¹⁰--10¹¹ kg of hydrogen and helium, and 10⁸--10⁹ kg of heavier elements (mostly oxygen, carbon, nitrogen, and neon). Helium and hydrogen will readily escape into space; the gravitational force of the Moon being much too feeble to hold on to such light atoms. The heavier elements will stick to the Moon much longer.

At present, particles reside only for very short periods of time in the extremely thin lunar atmosphere because they all interact with the solar wind within a few weeks. A less thin atmosphere could deflect the solar wind, its upper layers protecting the deeper layers from interactions; this would greatly enlarge the stability of the atmosphere. NASA scientist Richard Vondrak calculated that during a year only about 10⁸ kg of atmospheric mass can be carried away by solar wind interactions. There is no other atmospheric loss mechanism that is important on a time-scale of years for gases heavier than helium; dumping 10⁹ kg or more of heavy gases into the lunar environment will thus create a rapidly thickening atmosphere.

If the formation of a lunar atmosphere is unwanted, precautions must be taken. The undesirable furnaces could be placed in space, and heavy excess gases could be injected into the Moons crust, where they can react chemically and bind to the soil.

If on the other hand the formation of an even thicker atmosphere is desired, a few nuclear bombs could be used to evaporate lunar rocks, which would free most of the oxygen in them. One percent of the US nuclear stockpile could set free as much as 10¹¹ kg of oxygen.


A 10¹¹ kg Lunar Atmosphere

· Will mainly consist of O₂, but may contain important fractions of N₂, CO₂, and Ne if partly induced by ³₂He mining.

· Will be partly ionized, even near the surface.

· Will be stable for hundreds of years

· Will have surface pressure about 10^-2 Pa (=10^-7 Atm), comparable to Earths atmosphere at an altitude of 100 km.

· Will stop all micro meteorites, and most larger ones as well.

· Will deflect the solar wind, stop almost all cosmic ray particles and roentgen photons, and will thus strongly reduce the radiation level at the Moons surface (now in the order of 10 REM/year, limit for nuclear workers is 5 REM/year)

· Will stop deposition of ³₂He into the lunar surface. Deposition is a slow process and stopping it will only cause significant effects after thousands of years.

· Apart from some aurora, it will be completely invisible to the naked eye.


A Speculative Scenario: Relocating Ice-Dwarfs

James Oberg: “Go to the outer solar system, get a small ice-dwarf and dump it onto the Moon. This will create a thick and moist atmosphere, from which the Moon can be truly Terra-formed.”

Of course this idea is pretty far over the top for the moment, but is it impossible? If so, why?

Is it possible to move around ice-dwarfs with the techniques of the foreseeable future? To set the dimensions of this problem: could humanity ship Mount Everest to Latin America, or could it dump 10% of the Antarctic ice-cap onto the Sahara? Such would be difficult projects, but once properly motivated humans can achieve great enterprises. E.g., near the closing of the last century people discovered gold in a small mountain range somewhere in Southern Africa; within a few years the whole range was shoveled away and all that remained was a tremendously large hole. If a few thousand people can displace several cubic kilometers with not much more than shovels and their bare hands, one may expect that the organized power of Caterpillar, Boskalis, and Smit-Tak could move mildly larger objects like Mount Everest and major parts of the Antarctic ice-cap.

But could such undertakings be performed in space? Not right now: of course not. However, if several trillion dollars were already spent on creating large space-based industries, the answer would be different. Of course it would be costly, and it could well take a hundred years or so to transfer the ice-dwarf, but with heavy industries already in space the mission wouldn't really be difficult, not even with present day technology.

Chemistry of the Lunar Soil

Is it wise to impact an ice-dwarf onto the Moon? I doubt it.

A lunar oxygen atmosphere can exist for many centuries, but only if it is very thin and in the absence of water. What if this atmosphere were moist and oxygen rich?

The upper few kilometers of the lunar surface contain several times 10¹⁸ kg of iron(II) which in the presence of water would readily react with oxygen to form iron(III). Such an amount of iron(II) could easily absorb all of the oxygen in the Earth atmosphere.

A large fraction of the Moons crust consists of oxides of calcium, magnesium, and iron(II), which in the presence of water would react to form hydroxides that would (partly) dissolve in the forming seas to create a poisonously alkaline fluid, with pH 10--11. If enough oxygen were available to oxidize the dissolved iron(II)hydroxides, insoluble iron(III)hydroxides would precipitate on the sea floors and shores, creating vast quantities of slightly poisonous, orange mud. Such reactions would be violent and fast in the upper part of the crust, but their rate would decrease with increasing depth. The oxidizing, hydration, and other processes would continue for ages. In the meantime oxygen and other pressures would not be stable. Most of important all: the absorption of such enormous amounts of oxygen, water, by the upper part of the crust of the Moon would make the rocks expand by perhaps as much as ten percent or more. One can wonder if such expansion would be a tranquil process. It could create strong quakes for possibly many thousands of years.


Conclusions:

· Creation of a thin lunar atmosphere is perfectly feasible, even with present day technology, and in some scenarios even hard to avoid.

· Truly Terra-forming the Moon, if possible at all, could take thousands of years and might yield violent Moon quakes and a highly unstable, chemically aggressive environment during this long period.

quote:

Op dinsdag 30 augustus 2011 09:17 schreef ExperimentalFrentalMental het volgende:

[..]

correct

quote:

Atmosphere
Surface pressure 10^-7 Pa (day)
10^-10 Pa (night)
Composition Ar, He, Na, K, H,

quote:

Op maandag 29 augustus 2011 09:02 schreef ExperimentalFrentalMental het volgende:

[..]

Ik heb een Meade etx-70.
Kostte maar 100 euro (aanbieding) + statief. Degelijke telescoop (gemotoriseerd) met computer (1471 hemelobjecten voorgeprogrammeerd). De telescoop blijft, nadat het object gevonden is, deze met de juiste snelheid volgen. Zeker aan te raden.

http://www.meade-online.n(...)D386oCFQRO3godekX_7g

en anders moet je het hier eens vragen
Astronomie in de Achtertuin #1