Het Astronomie Topic #6

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Op maandag 29 augustus 2011 17:34 schreef Kirov het volgende:
Heeft de Maan niet gewoon te weinig zwaartekracht om een atmosfeer vast te houden?

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It may not be much use to hitchhikers through the galaxy, but it is extremely valuable to astronomers: the new radio atlas of the Milky Way. After almost ten years of work, researchers at the Max Planck Society and the Chinese Academy of Sciences have completed their investigation into the polarised radio emission in the galactic plane. The atlas is based on observations undertaken with the 25-metre radio telescope in the Chinese city of Urumqi and shows an area of 2,200 square degrees of the sky.



The radio survey covers the northern band of the Milky Way between ten and 230 degrees galactic longitude and between minus five and plus five degrees galactic latitude. The comprehensive survey shows the polarised radio emission of our galaxy at five gigahertz (corresponding to a wavelength of six centimetres) and thus at the highest frequency every recorded by terrestrial instruments.

The interstellar medium of the Milky Way comprises magnetic fields, electrons, atomic gas and other components which affect the polarisation plane of the radio emission.

The Partner Group of the Max Planck Institute for Radio Astronomy, which was set up at the National Astronomical Observatory (NAO) in Beijing, investigated the properties of regions of large-scale diffuse emission and mapped the structure of large objects which cannot be observed by larger radio telescopes. These include densely ionised clouds - the HII regions - and the remnants of exploded stars.

The aim of the project was to map the large-scale magnetic field of the Milky Way. The German and Chinese researchers found a handful of peculiar clumps with very strong, regular magnetic fields (Faraday screens) and two new supernova remnants each measuring around one degree.

These are the first sources of this type to be discovered with a Chinese radio telescope; astronomers are currently only aware of 270 such objects in the Milky Way. The researchers were also able to classify two incorrectly identified supernova remnants as thermal radio sources.

The new atlas needed more than 4,500 hours of observations to compile, and its angular resolution is similar to that of the 21-cm wavelength survey of the Milky Way obtained at the 100-metre radio telescope at Effelsberg. The comparative analysis of these two large-scale sky surveys at similar angular resolution leads to a better understanding of the processes occurring in the interstellar medium.

The establishment of the Partner Group in China dates back to a resolution of the Max Planck Society on November 9, 2000. The proposal involved collaboration in the exploration of magnetic fields in galaxies with special emphasis being placed on the investigation of the magnetic field of our Milky Way.

The most important contribution made by the Max Planck Institute for Radio Astronomy in Bonn relates to the construction of a receiver for radio emission at six-centimetre wavelength including polarisation, which is being used at the 25-metre Nanshan radio telescope in Urumqi.

The advantage of this radio telescope is its location at an altitude of 2,000 metres, where the better weather conditions are advantageous when observing radio emission at higher frequencies.

"Reciprocal visits to the institutes involved have formed a whole series of personal contacts," says Richard Wielebinski, emeritus Director at the Max Planck Institute for Radio Astronomy. "As far as the German researchers are concerned, we have established a good collaboration with our Chinese colleagues. Things which began with the Partner Group will be continued on a personal level."

"In the course of our work on this project, a total of five doctorates have been completed in our research group," says Jin-Lin Han, the Head of the Partner Group in Beijing. "Our collaboration has significantly boosted the development of radio astronomy in China. The way the objective of the Partner Group has been achieved is excellent."

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Op maandag 15 augustus 2011 09:29 schreef Googolplexian het volgende:
Met nieuwe kennis en nieuwe beelden komen ook nieuwe filmpjes die e.e.a. uitleggen

Extreme Solar Flares

met als contrast een filmpje uit Sagan's tijd

Carl SaganThe Life Cycle of a Star

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Op donderdag 1 september 2011 14:16 schreef Pulzzar het volgende:

[..]

Ik heb ooit zo'n DVD-box van Carl Sagan gekocht. Ik had toen er nooit van gehoord en dacht eigenlijk dat die box recenter materiaal bevat. Toen ik de DVD's voor het eerst bekeek, dacht ik dat ik een miskoop had begaan. Ik zag alleen maar beelden van slechtere kwaliteit en alleen maar die Carl die dingen aan het uitleggen was.

Pas geleden ben ik die box weer wezen kijken. Ik moet zeggen dat ik het toch wel een interessante serie vind. Knap gemaakt ook voor die tijd (1980).

James Randi Speaks: Carl Sagan

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NASA on Saturday launched a $500 million pair of washing-machine-sized satellites on a mission to map the Moon's inner core for the first time.

The twin spacecraft took off from Cape Canaveral Air Force Station in Florida on a three-month journey to the Moon at 9:08 am (1308 GMT) aboard a Delta II rocket.

"Liftoff of the Delta II with GRAIL, on a journey to the center of the moon," NASA commentator George Diller said upon blast-off of the GRAIL mission, which stands for Gravity Recovery and Interior Laboratory

High upper level winds delayed the first launch attempt on Thursday, and also briefly set back Saturday's launch.

The duo will travel to the Moon for more than three months, arriving into a polar lunar orbit one after the other around New Year's Day.

With one spacecraft trailing the other, the plan is for the two to use gravity tools to map the terrain beneath, revealing the contents of the inner core of the Moon, about which little is known.

The mission should also shed light on the unexplored far side of the Moon, and perhaps tell scientists whether there was once a second Moon that fused with ours.

"GRAIL will be the first mission to determine the internal structure of the Moon," program scientist Bobby Fogel told reporters this week.

"We have used gravity science before to try to gain some insight as to what is going on inside the Moon, however these have been very primitive attempts.

"If those previous attempts could be likened to a magnifying glass, GRAIL by contrast would be a high-powered microscope."

Scientists believe that the Moon was formed when a planet-sized object crashed into the Earth, throwing off a load of material that eventually became what we now recognize as our planet's airless, desolate satellite.

How it heated up over time, creating a magma ocean that later crystallized, remains a mystery, despite 109 past missions to study the Moon since 1959, and the fact that 12 humans have walked on its surface.

A recent hypothesis that there may have been two Moons that slowly merged into each other can also be tested with this mission, said principal investigator Maria Zuber.

"If we want to reconstruct the evolution of the Moon over time, we certainly need to reconstruct the temperature structure of the Moon right now," she said.

Little is known for certain about what lies inside the Moon. The widely held belief that there is a small solid iron core surrounded by a liquid iron core is unproven, said Zuber.

"It is actually quite possible that deep inside the Moon the core could be titanium oxide, which is a material that would have fallen out or would have crystallized out of the magma ocean and sunk to the deep interior of the Moon," she said.

Once the GRAIL twins enter the orbit of the Moon, they will line up with each other and "essentially chase each other around in a polar orbit as the Moon rotates slowly underneath them," said Zuber.

They will hover about 34 miles (55 kilometers) above the lunar surface, with the distance between them ranging from 37 to 140 miles (60 to 225 kilometers), collecting measurements of the terrain beneath.

The duo will accomplish the mission's primary aim of understanding the Moon's inner character by performing a series of low-altitude gravity field measurements using what is known as a Ka-band ranging instrument.

The mission itself is relatively short in duration, just 90 days once the two spacecraft reach orbit.

About 40 days after their work is done, the pair will plunge into the lunar surface, NASA said. Scientific analysis of their data is expected to continue for a year.

The project is part of NASA's Discovery program, which has launched 10 spacecraft since 1992 to study the solar system.

Last month, NASA launched its billion-dollar solar-powered spacecraft Juno on a five-year journey to Jupiter aiming to discover what makes up the solar system's biggest planet.

After GRAIL, the US space agency plans to launch its Mars Science Laboratory in November on a nearly two-year journey to the red planet.

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Op dinsdag 13 september 2011 01:18 schreef kristyle het volgende:
Is er deze nacht een zeer heldere planeet te zien boven België/Nederland?
Of misschien het ISS?

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NASA’s Kepler Mission Discovers a World Orbiting Two Stars

NASA's Kepler mission has turned fiction into fact. A world with a double sunset that was first imagined in Star Wars over 30 years ago in a galaxy far, far away has become scientific reality. NASA's Kepler mission has made the first unambiguous detection of a circumbinary planet -- a planet orbiting, not one, but two stars -- 200 light-years from Earth.

The planet is cold and gaseous unlike Star Wars' Tatooine and is not thought to harbor life, but its discovery demonstrates the diversity of planets in our solar system.

Unequivocal evidence for the existence of a circumbinary planet has been limited, until now. Hints of their existence have been presented, but clear confirmation has been elusive. Kepler detected the planet through what is known as a planetary transit -- an event where the brightness of a star dims as a result of a planet crossing in front of it.

"This discovery provides confirmation of a new class of planetary systems that could harbor life. Given that most stars in our galaxy are part of a binary system, this means that the opportunities for life are much broader than if planets form only around single stars," said Kepler principal investigator William Borucki. "This milestone discovery confirms a theory that scientists have had for decades but could not be proven until now."

A research team, led by Laurance Doyle of the SETI Institute, used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets. Kepler is the first NASA mission capable of finding Earth-size planets in or near the "habitable zone," the region in a planetary system where liquid water can exist on the surface of the orbiting planet. This finding provides significant insight into the world of planetary formation.

"Theorists have been debating for years about whether giant planets could form around close binary star systems- some said yes, others said no," said theoretical astrophysicist Alan Boss of the Carnegie Institution of Washington. "Kepler has now answered this question with a resounding 'YES'!"

This discovery confirms that Kepler-16b is an inhospitable, cold world about the size of Saturn, and thought to be made up of about half rock and half gas. The parent stars are both smaller than our sun; one is 69 percent and the other only 20 percent the mass of the sun. Kepler-16b orbits around both stars every 229 days, similar to Venus’ 225-day orbit, but lies outside the system's habitable zone, where liquid water could exist on the surface, because the stars are cooler than our sun.

"Working in film, we are often tasked with creating something never before seen," said visual effects supervisor John Knoll of Industrial Light & Magic. "However, more often than not, scientific discoveries prove to be more spectacular than anything we dare imagine. There is no doubt these discoveries influence and inspire storytellers. Their very existence serves as cause to dream bigger, to open our mind to new possibilities beyond what we think we 'know'."

For more information about the Kepler-16 discovery, visit:

http://kepler.nasa.gov/Mission/discoveries/kepler16b/

For more information about NASA’s Kepler Mission, visit:

http://www.nasa.gov/kepler

For more information about NASA’s Ames Research Center, visit:

http://www.nasa.gov/ames

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Op dinsdag 13 september 2011 12:56 schreef Googolplexian het volgende:

Live, HD Streaming Views of Earth Coming Soon

UrtheCast Animation