Giant Ribbon Discovered at the Edge of the Solar System
by Dr. Tony Phillips
October 15, 2009

from ScienceNASA Website

 

For years, researchers have known that the solar system is surrounded by a vast bubble of magnetism.

 

Called the "heliosphere," it springs from the sun and extends far beyond the orbit of Pluto, providing a first line of defense against cosmic rays and interstellar clouds that try to enter our local space.

 

Although the heliosphere is huge and literally fills the sky, it emits no light and no one has actually seen it. Until now... NASA's IBEX (Interstellar Boundary Explorer) spacecraft has made the first all-sky maps of the heliosphere and the results have taken researchers by surprise.

 

The maps are bisected by a bright, winding ribbon of unknown origin:

 

IBEX's all-sky map of energetic neutral atom emission reveals a bright filament of unknown origin.

V1 and V2 indicate the positions of the Voyager spacecraft.

[more]

"This is a shocking new result," says IBEX principal investigator Dave McComas of the Southwest Research Institute. "We had no idea this ribbon existed - or what has created it. Our previous ideas about the outer heliosphere are going to have to be revised."

Although the ribbon looks bright in the IBEX map, it does not glow in any conventional sense. The ribbon is not a source of light, but rather a source of particles - energetic neutral atoms or ENAs.

 

IBEX's sensors can detect these particles, which are produced in the outer heliosphere where the solar wind begins to slow down and mix with interstellar matter from outside the solar system.

"This ribbon winds between the two Voyager spacecraft and was not observed by either of them," notes Eric Christian, IBEX deputy mission scientist at NASA's Goddard Space Flight Center.

 

"It's like having two weather stations, but missing the big storm that runs between them."

Unlike the Voyager spacecraft, which have spent decades traveling to the edge of the solar system for in situ sampling, IBEX stayed closer to home.

 

It is in Earth orbit, spinning around and collecting ENAs from all directions. This gives IBEX the unique "big picture" view necessary to discover something as vast as the ribbon.

The ribbon also has fine structure - small filaments of ENA emission no more than a few degrees wide:

 

 

The fine structure is as much of a mystery as the ribbon itself, researchers say.

One important clue:

The ribbon runs perpendicular to the direction of the galactic magnetic field just outside the heliosphere, as shown in the illustration below.

"That cannot be a coincidence," says McComas. But what does it mean? No one knows. "We're missing some fundamental aspect of the interaction between the heliosphere and the rest of the galaxy. Theorists are working like crazy to figure this out."

Understanding the physics of the outer heliosphere is important because of the role it plays in shielding the solar system against cosmic rays.

 

The heliosphere's size and shape are key factors in determining its shielding power and, thus, how many cosmic rays reach Earth. For the first time, IBEX is revealing how the heliosphere might respond when it bumps into interstellar clouds and galactic magnetic fields.

"IBEX is now making a second all-sky map, and we're eager to see if the ribbon is changing," says McComas. "Watching the ribbon evolve - if it is evolving - could yield more clues."


 


Voyager Makes an Interstellar Discovery
by Dr. Tony Phillips
December 23, 2009

from ScienceNASA Website

Spanish version


The solar system is passing through an interstellar cloud that physics says should not exist.

 

In the Dec. 24th issue of Nature, a team of scientists reveal how NASA's Voyager spacecraft have solved the mystery.

"Using data from Voyager, we have discovered a strong magnetic field just outside the solar system," explains lead author Merav Opher, a NASA Heliophysics Guest Investigator from George Mason University.

 

"This magnetic field holds the interstellar cloud together and solves the long-standing puzzle of how it can exist at all."

Voyager flies through the outer bounds of the heliosphere en route to interstellar space.

A strong magnetic field reported by Opher et al

 in the Dec. 24, 2009, issue of Nature is delineated in yellow.

 

The discovery has implications for the future when the solar system will eventually bump into other, similar clouds in our arm of the Milky Way galaxy.

Astronomers call the cloud we're running into now the Local Interstellar Cloud or "Local Fluff" for short. It's about 30 light years wide and contains a wispy mixture of hydrogen and helium atoms at a temperature of 6000°C.

 

The existential mystery of the Fluff has to do with its surroundings. About 10 million years ago, a cluster of supernovas exploded nearby, creating a giant bubble of million-degree gas.

 

The Fluff is completely surrounded by this high-pressure supernova exhaust and should be crushed or dispersed by it.

"The observed temperature and density of the local cloud do not provide enough pressure to resist the 'crushing action' of the hot gas around it," says Opher.

So how does the Fluff survive?

 

The Voyagers have found an answer.

"Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected - between 4 and 5 microgauss *," says Opher.

 

"This magnetic field can provide the extra pressure required to resist destruction."

* A microgauss is one millionth of a gauss, a unit of magnetic field strength popular among astronomers and geophysicists. Earth's magnetic field is about 0.5 gauss or 500,000 microgauss.

 

An artist's concept of the Local Interstellar Cloud, also known as the "Local Fluff."

Credit: Linda Huff (American Scientist) and Priscilla Frisch (University of Chicago)

[more]
 

NASA's two Voyager probes have been racing out of the solar system for more than 30 years.

 

They are now beyond the orbit of Pluto and on the verge of entering interstellar space - but they are not there yet.

"The Voyagers are not actually inside the Local Fluff," says Opher. "But they are getting close and can sense what the cloud is like as they approach it."

The Fluff is held at bay just beyond the edge of the solar system by the sun's magnetic field, which is inflated by solar wind into a magnetic bubble more than 10 billion km wide.

 

Called the "heliosphere," this bubble acts as a shield that helps protect the inner solar system from galactic cosmic rays and interstellar clouds. The two Voyagers are located in the outermost layer of the heliosphere, or "heliosheath," where the solar wind is slowed by the pressure of interstellar gas.

Voyager 1 entered the heliosheath in Dec. 2004; Voyager 2 followed almost 3 years later in Aug. 2007.

 

These crossings were key to Opher et al's discovery.

 

The anatomy of the heliosphere.

Since this illustration was made, Voyager 2 has joined Voyager 1 inside the heliosheath,

a thick outer layer where the solar wind is slowed by the pressure of interstellar gas.

Credit: NASA/Walt Feimer.

 

The size of the heliosphere is determined by a balance of forces: Solar wind inflates the bubble from the inside while the Local Fluff compresses it from the outside.

 

Voyager's crossings into the heliosheath revealed the approximate size of the heliosphere and, thus, how much pressure the Local Fluff exerts. A portion of that pressure is magnetic and corresponds to the ~5 microgauss Opher's team has reported in Nature.

The fact that the Fluff is strongly magnetized means that other clouds in the galactic neighborhood could be, too. Eventually, the solar system will run into some of them, and their strong magnetic fields could compress the heliosphere even more than it is compressed now. Additional compression could allow more cosmic rays to reach the inner solar system, possibly affecting terrestrial climate and the ability of astronauts to travel safely through space.

 

On the other hand, astronauts wouldn't have to travel so far because interstellar space would be closer than ever.

 

These events would play out on time scales of tens to hundreds of thousands of years, which is how long it takes for the solar system to move from one cloud to the next.

"There could be interesting times ahead!" says Opher.

To read the original research, look in the Dec. 24, 2009, issue of Nature for Opher et al's article, "A Strong, Highly-Tilted Interstellar Magnetic Field Near The Solar System."

 

Back to The Photon Belt


 



Mystery of the Giant Ribbon, Solved?

by Dr. Tony Phillips
January 15, 2010

from ScienceNASA Website


Last year, when NASA's IBEX (Interstellar Boundary Explorer) spacecraft discovered a giant ribbon at the edge of the solar system, researchers were mystified. They called it a "shocking result" and puzzled over its origin.

 

Now the mystery may have been solved.

"We believe the ribbon is a reflection," says Jacob Heerikhuisen, a NASA Heliophysics Guest Investigator from the University of Alabama in Huntsville.

 

"It is where solar wind particles heading out into interstellar space are reflected back into the solar system by a galactic magnetic field."

Heerikhuisen is the lead author of a paper reporting the results in the Jan.10th edition of the Astrophysical Journal Letters.

 

An artist's concept of the Interstellar Boundary Explorer (IBEX).

"This is an important finding," says Arik Posner, IBEX program scientist at NASA Headquarters.

 

"Interstellar space just beyond the edge of the solar system is mostly unexplored territory. Now we know, there could be a strong, well-organized magnetic field sitting right on our doorstep."

The IBEX data fit in nicely with recent results from Voyager (above report).

 

Voyager 1 and 2 are near the edge of the solar system and they also have sensed strong* magnetism nearby.

 

Voyager measurements are relatively local to the spacecraft, however. IBEX is filling in the "big picture." The ribbon it sees is vast and stretches almost all the way across the sky, suggesting that the magnetic field behind it must be equally vast.

Although maps of the ribbon (see below) seem to show a luminous body, the ribbon emits no light. Instead, it makes itself known via particles called "energetic neutral atoms" (ENAs) - mainly garden-variety hydrogen atoms.

 

The ribbon emits these particles, which are picked up by IBEX in Earth orbit.

A comparison of IBEX observations (left)

with a 3D magnetic reflection model (right).

 

More images: data (left), model (right).


The reflection process posited by Heerikhuisen et al. is a bit complicated, involving multiple "charge exchange" reactions between protons and hydrogen atoms. The upshot, however, is simple.

 

Particles from the solar wind that escape the solar system are met ~100 astronomical units (~15 billion kilometers) away by an interstellar magnetic field.

 

Magnetic forces intercept the escaping particles and sling them right back where they came from.

"If this mechanism is correct - and not everyone agrees - then the shape of the ribbon is telling us a lot about the orientation of the magnetic field in our corner of the Milky Way galaxy," notes Heerikhuisen.

And upon this field, the future may hinge.

The solar system is passing through a region of the Milky Way filled with cosmic rays and interstellar clouds. The magnetic field of our own sun, inflated by the solar wind into a bubble called the "heliosphere," substantially protects us from these things.

 

However, the bubble itself is vulnerable to external fields. A strong magnetic field just outside the solar system could press against the heliosphere and interact with it in unknown ways.

 

Will this strengthen our natural shielding - or weaken it?

 

No one can say.

 

An artist's concept of interstellar clouds in the galactic neighborhood of the sun.

[more]

"IBEX will monitor the ribbon closely in the months and years ahead," says Posner. "We could see the shape of the ribbon change - and that would show us how we are interacting with the galaxy beyond."

It seems we can learn a lot by looking in the mirror.




NASA Baffled by Giant Space Ribbon
March 14, 2010

from LouisVillemojo Website


It sounds like something out of Star Trek, but it's all too real: a few months ago NASA's IBEX (Interstellar Boundary Explorer) spacecraft discovered a giant ribbon of atomic particles (above reports) floating at the edge of our solar system.

Nothing like the space ribbon has ever been seen before, and when NASA scientists first saw the data, they were stunned. As they double-checked the data and determined that the readings were not in error, and as they realized the immense size of what they were beholding, they may well have had the same creeping sense of horror and awe as when it gradually dawned on the cast of Star Wars that they were seeing the Death Star.

NASA found itself in the nervous position of having to publicly admit that there was something huge, radioactive and invisible out there, right by our own solar system, and we have no clue what it's doing there.

 

Not only that, but both our previous Voyager deep-space probes failed to detect it.

"This is a shocking new result," said IBEX principal investigator Dave McComas. "We had no idea this ribbon existed - or what has created it."

The current attempt to explain the mysterious ribbon is a theory that it's a reflection of solar wind particles being reflected back into the solar system by a galactic magnetic field.

 

They've whipped up a mathematical model that, made to order, predicts a boomerang shaped barrier much like the one that is baffling astronomers.

 

Not everyone agrees with the theory, however, and we can probably expect much wrangling, arguing, and forehead-smiting for a long time to come.

"This is an important finding," says Arik Posner, IBEX program scientist, quoted on NASA's website. "Interstellar space just beyond the edge of the solar system is mostly unexplored territory. Now we know, there could be a strong, well-organized magnetic field sitting right on our doorstep."

What this means for Earth's future is uncertain.

 

As the latest NASA article on the space ribbon states:

And upon this field, the future may hinge.

 

The solar system is passing through a region of the Milky Way filled with cosmic rays and interstellar clouds. The magnetic field of our own sun, inflated by the solar wind into a bubble called the "heliosphere," substantially protects us from these things. However, the bubble itself is vulnerable to external fields. A strong magnetic field just outside the solar system could press against the heliosphere and interact with it in unknown ways.

 

Will this strengthen our natural shielding - or weaken it? No one can say.

These discoveries about the outer fringe of our solar system come at a time when new NASA revelations have piled up so fast and so frequently that our paradigm is completely changing again and again without the general public even really being aware.

 

Most of us grew up being told in school that there were nine, maybe ten, planets in the solar system, and we now know that there are hundreds of thousands of them.

 

And far from being chunky bits of asteroid debris as previously believed, we now know that many of them are spherical and even have their own moons, like the planet Pulcova or the planet Haumea or the astonishingly Earth-like planet Ceres.

It's a whole new ball game in space.

 

 

(And it presents a real migraine for astrologers, I'm sure, who are now faced with the problem of charting over 231,665 planets in our solar system alone! And that doesn't even include the 430 known planets in other star systems.)