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news.bbc.co.uk/2/hi/scien...8309179.stm
The first results from Nasa's Interstellar Boundary Explorer (Ibex) spacecraft have shown unexpected features at our Solar System's edge.
Ibex was launched nearly one year ago to map the heliosphere, the region of space defined by the extent of our Sun's solar wind.
Ibex's first glimpses show that the heliosphere is not shaped as many astronomers have believed.
A series of papers in the journal Science outlines the results.
Our Solar System is whipping around the centre of the galaxy. Just like a hand held out of a moving car, the Solar System feels a "wind" of particles from the region between our star and its nearest neighbours.
At the same time, the solar wind - a constant stream of fast-moving particles in all directions - blows outwards from the Sun.
The boundary at which the incoming and outgoing particles are at equivalent pressures, known as the heliopause, defines the heliosphere - the "bubble" in space generated by our own Sun's exhalations.
True shape
The true extent and shape of the heliosphere has been a subject of debate for more than half a century. Until now, the best clues came from the two Voyager spacecraft, which are believed to have passed through the heliopause at two different distances.
Through a process known as "charge exchange" at the heliosphere's edge, fast-moving neutral or uncharged particles are created, and it is these energetic neutral atoms or ENAs that the Ibex spacecraft aims to measure.
It orbits the Earth in a vast ellipse, gathering incoming ENAs flying back from the heliopause at a range of speeds.
What a number of researchers have found is that the flow of the ENAs is uneven, with a significantly higher flow in a "ribbon" across the sky.
"The Ibex results are truly remarkable, with emissions not resembling any of the current theories or models of this never-before-seen region," said lead researcher Dr David McComas of the Southwest Research Institute in New Mexico.
"We expected to see small, gradual spatial variations at the interstellar boundary. However, Ibex is showing us a very narrow ribbon that is two to three times brighter than anything else in the sky."
Near miss
These concentrations of incoming particles were just missed by the Voyager spacecraft, Dr McComas explained.
"The most astounding feature in the Ibex sky maps - the bright narrow ribbon - snakes through the sky between the Voyager spacecraft, where it remained completely undetected until now," he said.
Further measurements were made by the Cassini spacecraft orbiting Saturn. It too has a "camera" that can capture incoming neutral atoms, and also observed a ribbon-shaped region across the sky, but from ENAs moving at slightly different speeds.
What is clear is that the heliosphere is not shaped like a comet, as previously thought, with a head pointed at the oncoming interstellar medium and a tail of matter trailing behind.
The research groups agree that the magnetic field interactions at the heliopause have as-yet undetermined effects on the overall shape. But the exact shape, and the forces that cause it, are still a matter of debate between the teams.
INTERSTELLAR BOUNDARY EXPLORER (IBEX)
*Completes a large, elliptical orbit around the Earth
*Measures uncharged atoms that enter the Solar System from the interstellar medium
*Can detect hydrogen, helium, and oxygen moving at a wide range of speeds through the Solar System
*Results should explain how interstellar magnetic fields form our heliosphere
The first results from Nasa's Interstellar Boundary Explorer (Ibex) spacecraft have shown unexpected features at our Solar System's edge.
Ibex was launched nearly one year ago to map the heliosphere, the region of space defined by the extent of our Sun's solar wind.
Ibex's first glimpses show that the heliosphere is not shaped as many astronomers have believed.
A series of papers in the journal Science outlines the results.
Our Solar System is whipping around the centre of the galaxy. Just like a hand held out of a moving car, the Solar System feels a "wind" of particles from the region between our star and its nearest neighbours.
At the same time, the solar wind - a constant stream of fast-moving particles in all directions - blows outwards from the Sun.
The boundary at which the incoming and outgoing particles are at equivalent pressures, known as the heliopause, defines the heliosphere - the "bubble" in space generated by our own Sun's exhalations.
True shape
The true extent and shape of the heliosphere has been a subject of debate for more than half a century. Until now, the best clues came from the two Voyager spacecraft, which are believed to have passed through the heliopause at two different distances.
Through a process known as "charge exchange" at the heliosphere's edge, fast-moving neutral or uncharged particles are created, and it is these energetic neutral atoms or ENAs that the Ibex spacecraft aims to measure.
It orbits the Earth in a vast ellipse, gathering incoming ENAs flying back from the heliopause at a range of speeds.
What a number of researchers have found is that the flow of the ENAs is uneven, with a significantly higher flow in a "ribbon" across the sky.
"The Ibex results are truly remarkable, with emissions not resembling any of the current theories or models of this never-before-seen region," said lead researcher Dr David McComas of the Southwest Research Institute in New Mexico.
"We expected to see small, gradual spatial variations at the interstellar boundary. However, Ibex is showing us a very narrow ribbon that is two to three times brighter than anything else in the sky."
Near miss
These concentrations of incoming particles were just missed by the Voyager spacecraft, Dr McComas explained.
"The most astounding feature in the Ibex sky maps - the bright narrow ribbon - snakes through the sky between the Voyager spacecraft, where it remained completely undetected until now," he said.
Further measurements were made by the Cassini spacecraft orbiting Saturn. It too has a "camera" that can capture incoming neutral atoms, and also observed a ribbon-shaped region across the sky, but from ENAs moving at slightly different speeds.
What is clear is that the heliosphere is not shaped like a comet, as previously thought, with a head pointed at the oncoming interstellar medium and a tail of matter trailing behind.
The research groups agree that the magnetic field interactions at the heliopause have as-yet undetermined effects on the overall shape. But the exact shape, and the forces that cause it, are still a matter of debate between the teams.
INTERSTELLAR BOUNDARY EXPLORER (IBEX)
*Completes a large, elliptical orbit around the Earth
*Measures uncharged atoms that enter the Solar System from the interstellar medium
*Can detect hydrogen, helium, and oxygen moving at a wide range of speeds through the Solar System
*Results should explain how interstellar magnetic fields form our heliosphere
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Re: Glimpses of Solar System's edge
Thu, October 15, 2009 - 2:59 PMAwesome, thanks Stickyboy.
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(Related)
Thu, October 15, 2009 - 4:34 PMNASA Science News for October 15, 2009
NASA's IBEX spacecraft has discovered a vast, glowing ribbon at the edge of the solar system. One mission scientist calls the discovery "shocking" and says theorists are "working like crazy" to explain the finding.
FULL STORY at
science.nasa.gov/headlines...t_ibex.htm
From: distribution email
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Cassini Data Help Redraw Shape of Solar System
Thu, October 15, 2009 - 4:38 PMFeature
Oct. 15, 2009
The full version of this story with accompanying images is at: www.jpl.nasa.gov/news/features.cfm
Images from the Ion and Neutral Camera on NASA's Cassini spacecraft suggest that the heliosphere, the region of the sun's influence, may not have the comet-like shape predicted by existing models. In a paper published Oct. 15 in Science Express, researchers from the Johns Hopkins Applied Physics Laboratory present a new view of the heliosphere, and the forces that shape it.
"These images have revolutionized what we thought we knew for the past 50 years; the sun travels through the galaxy not like a comet but more like a big, round bubble," said Stamatios Krimigis of the Applied Physics Lab, in Laurel, Md., principal investigator for Cassini's Magnetospheric Imaging Instrument which carries the Ion and Neutral Camera. "It's amazing how a single new observation can change an entire concept that most scientists had taken as true for nearly fifty years."
As the solar wind flows from the sun, it carves out a bubble in the interstellar medium. Models of the boundary region between the heliosphere and interstellar medium have been based on the assumption that the relative flow of the interstellar medium and its collision with the solar wind dominate the interaction. This would create a foreshortened "nose" in the direction of the solar system's motion, and an elongated "tail" in the opposite direction.
The Ion and Neutral Camera images suggest that the solar wind's interaction with the interstellar medium is instead more significantly controlled by particle pressure and magnetic field energy density.
"The map we've created from the images suggests that pressure from a hot population of charged particles and interaction with the interstellar medium's magnetic field strongly influence the shape of the heliosphere," says Don Mitchell, Magnetospheric Imaging Instrument/Ion and Neutral Camera co-investigator at the Applied Physics Lab.
Since entering into orbit around Saturn in July of 2004, the Ion and Neutral Camera has been mapping energetic neutral atoms near the planet, as well as their dispersal across the entire sky. The energetic neutral atoms are produced by energetic protons, which are responsible for the outward pressure of the heliosphere beyond the interface where the solar wind collides with the interstellar medium, and which interact with the magnetic field of the interstellar medium.
"Energetic neutral atom imaging has demonstrated its power to reveal the distribution of energetic ions, first in Earth's own magnetosphere, next in the giant magnetosphere of Saturn and now throughout vast structures in space-out to the very edge of our sun's interaction with the interstellar medium," says Edmond C. Roelof, Magnetospheric Imaging Instrument co-investigator at the Applied Physics Lab.
The results from Cassini complement and extend findings from NASA's Interstellar Boundary Explorer, or IBEX, spacecraft. Data from IBEX and Cassini have made it possible for scientists to construct the first comprehensive sky map of our solar system and its location in the Milky Way galaxy.
Researchers from University of Arizona, Tucson; Southwest Research Institute, San Antonio; and University of Texas at San Antonio contributed to the article. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The Magnetospheric Imaging Instrument was developed by the Applied Physics Laboratory.
More information on the Cassini mission is available at: www.nasa.gov/cassini, saturn.jpl.nasa.gov and on the Magnetospheric Imaging Instrument Web site at sd-www.jhuapl.edu/CASSINI/ .
More information on the Interstellar Boundary Explorer is available at: www.nasa.gov/ibex
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Re: Glimpses of Solar System's edge
Fri, October 16, 2009 - 3:29 AMVery cool, you guys! Thanks to you both : ) -
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Re: Glimpses of Solar System's edge
Wed, October 21, 2009 - 11:57 AMI'm glad NASA is taking an interest in the Heliosphere as promoted from data of Voyagers 1 and 2. I wondered where this starship Sol was taking us as it treks around the galaxy. Now it seems we have a big view screen to see what is out there, the heliosphere.
Hoping that better monitoring of this will help us make new discoveries about what is native to the solar system and what comes in from other solar systems or nebulae.
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