Het Astronomie Topic #8

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Most detailed map of Big Bang radiation unveiled

AFP - The European Space Agency (ESA) on Thursday unveiled the most detailed map yet of relic radiation from the Big Bang, revealing new data it hopes will shed light on the creation and expansion of our Universe.

The 50-million pixel, all-sky image of the oldest light adds an edge of precision to some existing cosmological theories, defining more precisely the composition of the Universe and its age -- about 80 million years older than previously thought.

"This is a giant leap in the understanding of the origins of the universe," the agency's director general Jean-Jacques Dordain told a press conference in Paris.

"This image is the closest one yet of the Big Bang. You are looking 13.8 billion years ago."

The map is composed of data gathered by ESA's Planck satellite, launched in May 2009 to study Cosmic Microwave Background -- the remains of ancient radiation emitted as the Universe started cooling after the Big Bang.

"What we are seeing is a picture of the microwave sky, a picture of the Universe as it was 380,000 after the Big Bang," George Efstathiou, director of the Kavli Institute for Cosmology at the University of Cambridge, told journalists.

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Op donderdag 21 maart 2013 08:08 schreef ExperimentalFrentalMental het volgende:
20-03-2013

"Ruimtesonde Voyager 1 heeft zonnestelsel verlaten"

[ afbeelding ]
Voyager 1. © epa.

Voor het eerst in de geschiedenis heeft een ruimtesonde ons zonnestelsel verlaten. De Voyager 1 blijkt in augustus vorig jaar, 35 jaar na zijn lancering, de eindeloze ruimte tussen de sterren te zijn binnengevlogen. Dat heeft de Amerikaanse Geofysische Unie (AGU) bekendgemaakt. NASA spreekt dat echter tegen.

De Voyager 1 vliegt op ongeveer 18 miljard kilometer van de aarde en meet daar constant de deeltjes die er zijn. Die gegevens worden teruggestuurd naar de aarde. Afgelopen augustus blijkt de hoeveelheid deeltjes van onze zon in een paar dagen tijd ongeveer 100 keer zo klein te zijn geworden. Straling die van buiten het zonnestelsel komt, is juist enorm gestegen. Dat wijst erop dat de Voyager voorbij de grens van ons zonnestelsel is, in een gebied waar onze zon geen invloed meer heeft.

NASA
De Amerikaanse sonde Voyager-1 heeft ons zonnestelsel nog niet verlaten, zo heeft de NASA vadaag gezegd.

"Volgens een consensus binnen de wetenschappelijke gemeenschap, is Voyager-1 ons zonnestelsel nog niet buitengegaan of in de interstellaire ruimte", staat in een communiqué van Edward Stone, wetenschappelijk verantwoordelijk voor de missie.

In december 2012 heeft de leiding van de missie gezegd dat de sonde zich nu in een nieuw gebied in de uiterste regio's van ons zonnestelsel bevindt, met name de "magnetische autoweg". Daar ondergaan hoog energetische deeltjes radicale wijzigingen, aldus Stone. "Een wijziging van de richting van het magnetisch veld is de laatste sleutelindicator om te bevestigen dat de sonde de interstellaire ruimte heeft bereikt. Deze richtingsverandering is nog niet waargenomen."

(HLN)

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The US space agency on Wednesday denied a claim made in a scientific study that its Voyager 1 spacecraft had left the solar system, describing the report as "premature."

Scientists are eagerly awaiting signs that the craft, which was launched in 1977 on a mission to study planets, has become the first man-made object to leave the boundaries of our solar system.

A scientific paper that purported to describe this departure appeared on the American Geophysical Union's web site.

It said Voyager 1 "appears to have traveled beyond the influence of the Sun and exited the heliosphere," or the magnetic bubble of charged particles that surround the solar system.

Researcher Bill Webber, one of the article's authors, acknowledged that the actual location of the spacecraft -- whether in interstellar space or just an unknown region beyond the solar system -- remained a matter of debate.

"It's outside the normal heliosphere, I would say that," said Webber, professor emeritus of astronomy at New Mexico State University in Las Cruces, according to the AGU's web site.

"We're in a new region. And everything we're measuring is different and exciting."

Shortly after the study appeared, NASA spokesman Dwayne Brown told AFP the report was "premature and incorrect."

The Voyager science team reported in December 2012 the craft was in a new region called the "magnetic highway," but changes in the magnetic field to show a departure from the solar system have not yet been observed, NASA said.

"The Voyager team is aware of reports today that NASA's Voyager 1 has left the solar system," said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, California.

"It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space," he said.

"A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed."

Voyager 1 and its companion Voyager 2 set off in 1977 on a mission to study planets. They have both kept going, and both are on track to leave the solar system, NASA has said.

For months, experts have been closely watching for hints that Voyager 1 has left the solar system and most have estimated that this will happen in the next year or two.

NASA has described Voyager 1 -- now 11 billion miles (18 billion kilometers) away from the Sun -- and its companion Voyager 2 as "the two most distant active representatives of humanity and its desire to explore."

The Voyager craft are both carrying gold-plated phonograph records and cartridges on which to play them.

They contain 115 images of Earth life, sounds made by whales, thunder and surf, spoken greetings in various languages and printed messages from former US president Jimmy Carter and former UN chief Kurt Waldheim.

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Op dinsdag 2 april 2013 08:58 schreef ExperimentalFrentalMental het volgende:
01-04-2013

Schrijf je naam op een planetoïde!

[ afbeelding ]
Illustratie van de Japanse planetoïdeverkenner Hayabusa-2. (Akihiro Ikeshita)

De Japanse ruimtevaartorganisatie JAXA nodigt iedereen uit om zijn of haar naam achter te laten op een kleine planetoïde. De actie start op 10 april en duurt tot half juli.

In juli 2014 moet de Japanse ruimtesonde Hayabusa-2 gelanceerd worden. In 2018 zal die aankomen bij de kleine Apollo-planetoïde (162173) 1999 JU3. Net als zijn voorganger (Hayabusa-1) dat deed bij de planetoïde Itokawa, zal Hayabusa-2 stofmonsters van het oppervlak van 1999 JU3 verzamelen die in 2020 teruggebracht zullen worden naar de aarde.

De 'landingsplaats' op de planetoïde zal permanent gemarkeerd worden door een klein bolvormig voorwerp, waarop microchips zijn bevestigd met ca. één miljoen namen van aardbewoners. Ook op de capsule die de bodemmonsters terugbrengt naar de aarde kunnen belangstellenden namen en boodschappen achterlaten. De webpagina's waarop namen kunnen worden ingestuurd zullen overigens pas op 10 april beschikbaar zijn. (GS)

(allesoversterrenkunde)

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Op woensdag 3 april 2013 21:37 schreef Parafernalia het volgende:
http://www.nu.nl/wetensch(...)materie-ontdekt.html

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A $2bn experiment on the space station has made observations that could prove to be the first signs of dark matter, a mysterious component of the Universe. The Alpha Magnetic Spectrometer (AMS) surveys the sky for high-energy particles, or cosmic rays. It has seen evidence of what may prove to be dark matter colliding with itself in what is known as "annihilation".
But scientists stress a precise description of this mysterious cosmic component is still some way off.
"It could take a few more years," AMS deputy spokesman Roberto Battiston, a professor of physics at the University of Perugia, told BBC News.

Dark matter accounts for most of the mass in the Universe. It cannot be seen directly with telescopes, but astronomers know it to be out there because of the gravitational effects it has on the matter we can see. Galaxies, for example, could not rotate the way they do and hold their shape without the presence of dark matter.

The AMS - a particle physics machine nicknamed the "Space LHC" in reference to the Large Hadron Collider here on Earth - has been hunting for some indirect measures of dark matter's properties. It counts the numbers of electrons and their anti-matter counterparts - known as positrons - falling on an array of detectors. Theory suggests that showers of these particles should be produced when dark-matter particles collide somewhere in space and destroy each other.

In a paper in the journal Physical Review Letters, the AMS team reports the observation of a slight excess of positrons in the positron-electron count - an outcome expected of these dark matter annihilations. The group also says the positrons fall on the AMS from all directions in the sky with no particular variation over time. This is important because specific locations or timing variations in the signal could indicate a more conventional source for the particles, such as a pulsar (a type of neutron star) rather than dark matter.

The AMS was placed on the International Space Station in 2011. The longer it operates, the better its statistics will be and the more definitive scientists can be in their statements. But lead spokesman, Prof Sam Ting, said the AMS Collaboration would proceed slowly. "It took us 18 years to do this experiment and we want to do it very carefully," he told a seminar at the European Laboratory for Particle Physics (Cern) in Geneva. "We will publish things when we are absolutely sure."

The Physical Review Letters paper reports the positron-electron count in the energy range of 0.5 to 350 gigaelectronvolts (GeV). The behaviour of the positron excess across this energy spectrum fits with the researchers' expectations. However, the "smoking gun" signature would be to see a rise in this ratio and then a dramatic fall. This has yet to be observed. "At the moment, all we can say is that the (dark matter) particles could have a mass of several hundred gigaelectronvolts, but there is much uncertainty," said Prof Battiston. (By way of comparison, a proton, the particle in the nucleus of every atom, has a mass of about 1 GeV).
Modern mysteries

The AMS is just one of several techniques being used by researchers to try to uncover the nature of dark matter. There are laboratories on Earth that are attempting to make more direct detections as the elusive particles pass though containers of the elements xenon or argon, held deep underground. The Large Hadron Collider, too, is involved in the hunt. It hopes to produce dark matter particles in its accelerator.

A precise description of this mysterious component is now an urgent objective for modern physics. Normal matter, the material we can see with telescopes (all the stars and galaxies), contributes just 4.9% of the mass/energy density of the Universe. Dark matter is a far bigger constituent, making up 26.8%. This figure was recently raised following studies of the cosmos by the European Space Agency's Planck telescope.

The value is now nearly a fifth up on previous estimates. Dark energy is the component that contributes most to the mass/energy density of the Universe at 68.3%. Dark energy is the name given to the force thought to be accelerating the expansion of the Universe. Its character is even more obscure to science than dark matter.