http://www.usnews.com/science/articles/ ... omers.html
Solar System's Edge Surprises Astronomers
By Ron Cowen, Science News
The edge of the solar system is tied up with a ribbon, astronomers have discovered. The first global map of the solar system reveals that its edge is nothing like what had been predicted. Neutral atoms, which are the only way to image the fringes of the solar system, are densely packed into a narrow ribbon rather than evenly distributed.
“Our maps show structure and energy spectra that are completely different from what any model has predicted,” says study coauthor Herbert Funsten of the Los Alamos National Laboratory in New Mexico.
NASA’s Interstellar Boundary Explorer satellite, or IBEX, discovered the narrow ribbon, which completes nearly a full circle across the sky. The density of neutral atoms in the band is two to three times that in adjacent regions.
These and related findings, reported in six papers posted online October 15 in Science, will not only send theorists back to the drawing board, researchers say, but may ultimately provide new insight on the interaction between the heliosphere — the vast bubble in which the solar system resides — and surrounding space.
The bubble is inflated by solar wind, the high-speed stream of charged particles blowing out from the sun to the solar system’s very edge. For 48 years, researchers have assumed that the solar wind sculpted the structure at the heliosphere’s boundary with interstellar space, says Tom Krimigis of Johns Hopkins University’s Applied Physics Laboratory in Laurel, Md.. But the newly found ribbon’s orientation suggests that the galaxy’s magnetic field, just outside the heliosphere, seems to be the chief organizer of structure in this region, says theorist Nathan Schwadron of Boston University, a lead author of one of the studies.
It’s not known whether the ribbon lasts for just a few years or is a permanent feature.
Equally puzzling are observations of the same boundary region with an instrument on the Cassini spacecraft, which recorded the density of atoms at higher energies, above 6,000 electron volts. From its vantage point at Saturn, Cassini sees a belt rather than a ribbonlike structure, a team led by Krimigis also reports in Science. The belt is substantially broader than the ribbon seen by IBEX but is in the same general area.
The heliosphere shields the solar system from 90 percent of energetic cosmic rays — high-speed charged particles that would otherwise bombard the planets and harm life. Understanding more about the heliosphere and its ability to filter out galactic cosmic rays could be critical for assessing the safety of human space travel, Schwadron notes. The new findings may also help predict how the heliosphere varies in shape and size as it moves through the galaxy and encounters regions of space having different densities and magnetic field strengths.
The ribbon found by IBEX, recorded at energies between 200 and 6,000 electron volts, is brightest at about 1,000 electron volts and lies between about 100 and 125 astronomical units from the sun, notes David McComas of the Southwest Research Institute in San Antonio. One astronomical unit is the distance between the Earth and the sun. The atoms recorded by IBEX, which orbits Earth, took a year or two, depending on their energies, to reach the craft from the outer edge of the heliosphere.
The IBEX ribbon runs perpendicular to the direction of the galaxy’s magnetic field at the interstellar boundary, an indication that the field has a much stronger than expected influence on the sun’s environs, report Schwadron and his colleagues. One possibility is that pressure from this external magnetic field has forced particles just inside the heliosphere to bunch together into a ribbon.
“First and foremost, this is a big surprise because we thought we know a lot about this region, the edge of the heliosphere,” McComas says. The Voyager 1 craft in 2004 (SN: 1/3/04, p. 7) and the Voyager 2 craft in 2007 (SN: 8/2/08, p. 7) journeyed to opposite sides of this fringe region of the solar system and crossed the termination shock — where the solar wind encounters a shock that precedes the influx of particles drifting into the solar system from interstellar space. Both craft recorded the density of particles and the strength of the magnetic fields.
Solar System's Edge Surprises Astronomers
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Solar System's Edge Surprises Astronomers
by Lit » Sat Oct 17, 2009 1:26 pm
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by Lit » Sat Oct 17, 2009 1:28 pm
http://news.nationalgeographic.com/news ... -ibex.html
In a discovery that took astronomers by surprise, the first full-sky map of the solar system's edge—more than 9 billion miles (15 billion kilometers) away—has revealed a bright "ribbon" of atoms called ENAs.
The solar system is surrounded by a protective "bubble" called the heliosphere.
The narrow ribbon snakes along this bubble's inner wall between Voyager 1 and 2, twin spacecraft that have been exploring the solar system's boundary since 2004 and 2007, respectively. (Related: "Voyager Probes Send Surprises From Solar System's Edge.")
Voyager data, taken from specific regions within the boundary zone, had offered no hint that the ribbon existed. But from its orbit around Earth, NASA's Interstellar Boundary Explorer, or IBEX, spacecraft was able to give researchers a wider view.
IBEX team member Eric Christian, of NASA's Goddard Space Flight Center, compared the Voyager spacecraft to weather stations on Earth.
"Can you imagine trying to determine the weather of the entire Earth from two weather stations? You can't do it," Christian told reporters at a press conference this afternoon.
"IBEX is like our first weather satellite, and it gives us the full picture [of the heliosphere]."
IBEX's map shows that the ribbon measures roughly two billion miles (three billion kilometers) long and several hundred thousand miles wide.
The ribbon isn't visible to people and wouldn't harm spacecraft or humans passing through it, IBEX principal investigator David McComas, of the Southwest Research Institute in Texas, told National Geographic News.
Astronomers aren't yet sure how the ribbon formed, but it's possible that the ribbon could be a result of pressure exerted on the heliosphere by our home galaxy's magnetic field.
Particle Crashes Seed Solar System Ribbon?
Since its launch almost a year ago, IBEX has been detecting the ENAs (energetic neutral atoms), atoms that have been stripped of their electric charges.
ENAs are created at the outer edges of the heliosphere, which is formed by solar wind—charged particles streaming rapidly outward in all directions from the sun.
Some gases from outside the heliosphere are constantly leaking in, and when the fast-moving solar wind meets these slow-moving gases, ENAs are born.
At the moment of their creation, some of these ENAs get shot toward Earth, where IBEX's sensors eventually detect them.
"We've observed about a million ENAs over the six months that it took to make the sky map," McComas said.
Ribbon a Sign of Heliosphere Being Squeezed?
The ENA ribbon's existence suggests the atoms are produced in higher densities in some parts of the outer heliosphere than others, McComas said, although scientists aren't yet sure why that would be the case.
One idea is that, wherever the Milky Way's magnetic field presses on the heliosphere, more ENAs are created.
"Exactly where the [galaxy's] magnetic field is most wrapped around the outer boundary of the heliosphere, that's where the ribbon runs," McComas said.
"That could be an unbelievably remarkable coincidence, or it could be a fabulous clue that somehow this external magnetic field is actually imprinting onto our heliosphere through some process that we don't yet understand."
The team is currently putting together the second IBEX sky map of the heliosphere, and there are already indications that the ribbon's shape is changing, McComas said.
"There's some suggestion," he said "that it's actually slightly different and maybe evolving over the 6 months since the [first sky map]."
Findings detailed in this week's issue of the journal Science.
In a discovery that took astronomers by surprise, the first full-sky map of the solar system's edge—more than 9 billion miles (15 billion kilometers) away—has revealed a bright "ribbon" of atoms called ENAs.
The solar system is surrounded by a protective "bubble" called the heliosphere.
The narrow ribbon snakes along this bubble's inner wall between Voyager 1 and 2, twin spacecraft that have been exploring the solar system's boundary since 2004 and 2007, respectively. (Related: "Voyager Probes Send Surprises From Solar System's Edge.")
Voyager data, taken from specific regions within the boundary zone, had offered no hint that the ribbon existed. But from its orbit around Earth, NASA's Interstellar Boundary Explorer, or IBEX, spacecraft was able to give researchers a wider view.
IBEX team member Eric Christian, of NASA's Goddard Space Flight Center, compared the Voyager spacecraft to weather stations on Earth.
"Can you imagine trying to determine the weather of the entire Earth from two weather stations? You can't do it," Christian told reporters at a press conference this afternoon.
"IBEX is like our first weather satellite, and it gives us the full picture [of the heliosphere]."
IBEX's map shows that the ribbon measures roughly two billion miles (three billion kilometers) long and several hundred thousand miles wide.
The ribbon isn't visible to people and wouldn't harm spacecraft or humans passing through it, IBEX principal investigator David McComas, of the Southwest Research Institute in Texas, told National Geographic News.
Astronomers aren't yet sure how the ribbon formed, but it's possible that the ribbon could be a result of pressure exerted on the heliosphere by our home galaxy's magnetic field.
Particle Crashes Seed Solar System Ribbon?
Since its launch almost a year ago, IBEX has been detecting the ENAs (energetic neutral atoms), atoms that have been stripped of their electric charges.
ENAs are created at the outer edges of the heliosphere, which is formed by solar wind—charged particles streaming rapidly outward in all directions from the sun.
Some gases from outside the heliosphere are constantly leaking in, and when the fast-moving solar wind meets these slow-moving gases, ENAs are born.
At the moment of their creation, some of these ENAs get shot toward Earth, where IBEX's sensors eventually detect them.
"We've observed about a million ENAs over the six months that it took to make the sky map," McComas said.
Ribbon a Sign of Heliosphere Being Squeezed?
The ENA ribbon's existence suggests the atoms are produced in higher densities in some parts of the outer heliosphere than others, McComas said, although scientists aren't yet sure why that would be the case.
One idea is that, wherever the Milky Way's magnetic field presses on the heliosphere, more ENAs are created.
"Exactly where the [galaxy's] magnetic field is most wrapped around the outer boundary of the heliosphere, that's where the ribbon runs," McComas said.
"That could be an unbelievably remarkable coincidence, or it could be a fabulous clue that somehow this external magnetic field is actually imprinting onto our heliosphere through some process that we don't yet understand."
The team is currently putting together the second IBEX sky map of the heliosphere, and there are already indications that the ribbon's shape is changing, McComas said.
"There's some suggestion," he said "that it's actually slightly different and maybe evolving over the 6 months since the [first sky map]."
Findings detailed in this week's issue of the journal Science.
- Lit
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by Lit » Sat Oct 17, 2009 1:34 pm
http://dsc.discovery.com/news/2009/10/1 ... y-map.html
Oct. 16, 2009 -- The bubble of gas enveloping Earth and the rest of the solar system has some seriously weird formations where it abuts interstellar space, a region expected to show only smooth uniformity.
"This is a shocking new result for us and one that is not entirely understood," said David McComas, the lead scientist on a NASA mission called IBEX to map the heliosphere, a region of space dominated by boil-off of the sun's corona into what is known as the solar wind.
The sun pumps out streams of ionized particles that blast out into space in all directions at about 1 million miles per hour, forming a protective bubble and defining edge to the solar system. But the rivers of gas face pressure -- and some unknown physics -- when and where they encounter charged particles and magnetic fields emanating from interstellar space.
The solar system is currently traveling through a rather wispy interstellar cloud in the Milky Way galaxy, which gives the heliosphere plenty of breathing room. But the outside world apparently has some sharp elbows.
In their first big-picture view of the heliosphere, scientists discovered a well-defined ribbon of neutrally charged particles, precisely tailored -- process unknown -- by magnetic fields in the interstellar sea.
"This ribbon is organized around this magnetic field," said Rosine Lallement, senior scientist at the French National Center for Scientific Research in Paris. "It is truly new physics."
The ribbon snakes right between two NASA Voyager spacecraft, which reached the boundary zone between the heliosphere and interstellar space in 2004 and 2007.
The Voyager twins were launched in 1977 to explore the outer planets of the solar system. They took different paths toward the edge of the solar system and continue to radio data back to Earth about their local environments.
"Voyager 1 and Voyager 2 are like weather stations, but can you imagine trying to determine the weather on the entire Earth from two weather stations?" said Eric Christian, IBEX deputy mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
"They were both out there making these local observation and had no idea that the main 'storm' so to speak was running right down between them," added McComas, a senior executive director with the San Antonio, Texas-based Southwest Research Institute.
From a long, looping orbit around Earth, IBEX -- an acronym for Interstellar Boundary Explorer -- scans the whole sky for electrically neutral atoms coming in from the very edge of the heliosphere roughly 10 billion miles away.
"Sometimes a particle can come close to another particle and steal an electron. They then go zipping off in whatever direction they were going and some of them go right back in toward us and go right into the aperture of the IBEX spacecraft," McComas said.
Scientists had expected slight variations in the numbers of these energetic neutral atoms across the heliosphere, but IBEX found concentrations of up to about 300 percent.
"It shows that what we thought we understood about this interaction is definitely not right," McComas said. "We kind of have to go back and start over."
The discovery, reported in this week's Science, was verified by secondary measurements made by the IBEX instruments and also by a similar instrument on the Saturn-orbiting Cassini spacecraft.
The IBEX team is beginning to piece together a second all-sky map and already has gotten hints that the ribbon is changing.
"It's really going to be fascinating to watch this feature potentially change over years," McComas said.
Oct. 16, 2009 -- The bubble of gas enveloping Earth and the rest of the solar system has some seriously weird formations where it abuts interstellar space, a region expected to show only smooth uniformity.
"This is a shocking new result for us and one that is not entirely understood," said David McComas, the lead scientist on a NASA mission called IBEX to map the heliosphere, a region of space dominated by boil-off of the sun's corona into what is known as the solar wind.
The sun pumps out streams of ionized particles that blast out into space in all directions at about 1 million miles per hour, forming a protective bubble and defining edge to the solar system. But the rivers of gas face pressure -- and some unknown physics -- when and where they encounter charged particles and magnetic fields emanating from interstellar space.
The solar system is currently traveling through a rather wispy interstellar cloud in the Milky Way galaxy, which gives the heliosphere plenty of breathing room. But the outside world apparently has some sharp elbows.
In their first big-picture view of the heliosphere, scientists discovered a well-defined ribbon of neutrally charged particles, precisely tailored -- process unknown -- by magnetic fields in the interstellar sea.
"This ribbon is organized around this magnetic field," said Rosine Lallement, senior scientist at the French National Center for Scientific Research in Paris. "It is truly new physics."
The ribbon snakes right between two NASA Voyager spacecraft, which reached the boundary zone between the heliosphere and interstellar space in 2004 and 2007.
The Voyager twins were launched in 1977 to explore the outer planets of the solar system. They took different paths toward the edge of the solar system and continue to radio data back to Earth about their local environments.
"Voyager 1 and Voyager 2 are like weather stations, but can you imagine trying to determine the weather on the entire Earth from two weather stations?" said Eric Christian, IBEX deputy mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
"They were both out there making these local observation and had no idea that the main 'storm' so to speak was running right down between them," added McComas, a senior executive director with the San Antonio, Texas-based Southwest Research Institute.
From a long, looping orbit around Earth, IBEX -- an acronym for Interstellar Boundary Explorer -- scans the whole sky for electrically neutral atoms coming in from the very edge of the heliosphere roughly 10 billion miles away.
"Sometimes a particle can come close to another particle and steal an electron. They then go zipping off in whatever direction they were going and some of them go right back in toward us and go right into the aperture of the IBEX spacecraft," McComas said.
Scientists had expected slight variations in the numbers of these energetic neutral atoms across the heliosphere, but IBEX found concentrations of up to about 300 percent.
"It shows that what we thought we understood about this interaction is definitely not right," McComas said. "We kind of have to go back and start over."
The discovery, reported in this week's Science, was verified by secondary measurements made by the IBEX instruments and also by a similar instrument on the Saturn-orbiting Cassini spacecraft.
The IBEX team is beginning to piece together a second all-sky map and already has gotten hints that the ribbon is changing.
"It's really going to be fascinating to watch this feature potentially change over years," McComas said.
- Lit
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- Posts: 2293
- Joined: Tue Mar 24, 2009 6:32 am
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by Lit » Sat Oct 17, 2009 1:40 pm
NASA finds 'space ribbon' at solar system's edge
http://www.tgdaily.com/content/view/44321/184/
While mapping the solar system's edge for the first time, NASA's Interstellar Boundary Explorer (IBEX), spacecraft has discovered a 'space ribbon' two billion miles long.
As the solar wind reaches the edge of the solar system and collides with the interstellar medium, a shock wave forms, heating particles which then stream away from the boundary.
"We have discovered an arc-shaped ribbon of high-pressure material that looks to be piled-up material from the Sun," says team member Herbert Funsten. "The IBEX maps and the discovery of the ribbon are completely different from what we thought it should look like. We were expecting tie-dye and instead found noodle soup."
What the mission has not found is what it was expecting - evidence of large-scale dynamic processes like the storms and tornados that result from the collision of a cold front and a warm front.
"The ribbon follows a circular arc of high pressure that we believe is centered on the direction of the magnetic field of the interstellar cloud through which we are moving," Funsten said. This magnetic field seems to fundamentally organize the interaction region.
The sky map was produced with data collected by two detectors on the spacecraft over a six-months period. The detectors measured and counted particles known as energetic neutral atoms.
"For the first time, we're sticking our heads out of the sun's atmosphere and beginning to really understand our place in the galaxy," said David J McComas, IBEX principal investigator. "The IBEX results are truly remarkable, with a narrow ribbon of bright details or emissions not resembling any of the current theoretical models of this region."
http://www.tgdaily.com/content/view/44321/184/
While mapping the solar system's edge for the first time, NASA's Interstellar Boundary Explorer (IBEX), spacecraft has discovered a 'space ribbon' two billion miles long.
As the solar wind reaches the edge of the solar system and collides with the interstellar medium, a shock wave forms, heating particles which then stream away from the boundary.
"We have discovered an arc-shaped ribbon of high-pressure material that looks to be piled-up material from the Sun," says team member Herbert Funsten. "The IBEX maps and the discovery of the ribbon are completely different from what we thought it should look like. We were expecting tie-dye and instead found noodle soup."
What the mission has not found is what it was expecting - evidence of large-scale dynamic processes like the storms and tornados that result from the collision of a cold front and a warm front.
"The ribbon follows a circular arc of high pressure that we believe is centered on the direction of the magnetic field of the interstellar cloud through which we are moving," Funsten said. This magnetic field seems to fundamentally organize the interaction region.
The sky map was produced with data collected by two detectors on the spacecraft over a six-months period. The detectors measured and counted particles known as energetic neutral atoms.
"For the first time, we're sticking our heads out of the sun's atmosphere and beginning to really understand our place in the galaxy," said David J McComas, IBEX principal investigator. "The IBEX results are truly remarkable, with a narrow ribbon of bright details or emissions not resembling any of the current theoretical models of this region."
- Lit
- Regular Contributor
- Posts: 2293
- Joined: Tue Mar 24, 2009 6:32 am
- Location: Right behind ya
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