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

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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