December 23, 2009: 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.”
Right: 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. Image copyright 2009, The American Museum of Natural History. [larger image]
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.”
Above: 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.
Right: 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. [larger image]
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.”
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
James F. Evans (11:58:59) :
Could be the “scattering effect” is caused by interactions of plasma at their boundary contact with other bodies of plasma.
And what has been observed & measured in the plasma laboratory by repeated experiments is that Electric Double Layers develope between plasma bodies with different physical properties such as density, temperature, magnetic field strength, relative motion and velocity.
Electric Double Layers cause dynamic changes to the flow and organization of the plasma supporting the process.
Interesting stuff. On the face of it, it seems it might be pretty difficult to observe and quantify this stuff. Just like the difficulty we have in measuring the flow of energy inside the Earth’s oceans. Argo has made some progress with that. I look forward to probes being launched in their thousands into the solar system to monitor it all so we can get a better handle on the flow of the fluxes. 🙂
John (10:09:06) :
Interesting, but how does this have any bearing on our climate and ice age cycle?
You might want to start exploring this question by downloading this:
http://nzclimatescience.net/index.php?option=com_content&task=view&id=19&Itemid=1
Click on download pdf. “Cosmoclimatology” is an easy read, and it outlines the brilliant Svensmark theory.
Chris
Norfolk, VA, USA
This is great news – from Nature (can we really believe it?)
@ur momisugly 6000 deg C its great that its a distance away but we are still going to get some effect – a bit more than co2, I’d wager.
Beautiful graphics.
Great electronics – wish my computers had a chance of lasting so long.
Goes to show we still have a lot to learn.
Thanks Anthony for including this.
Leif Svalgaard (12:08:01) :
James F. Evans (11:58:59) :
And what has been observed & measured in the plasma laboratory by repeated experiments is that Electric Double Layers develops between plasma bodies with different physical properties such as density, temperature, magnetic field strength, relative motion and velocity.
And precisely those double layers carry no current. They are known as ‘current-free double layers’. Even wikipedia has this correct:
“Current-free double layers occur at the boundary between plasma regions with different plasma properties”
There’s no current flowing around a permanent magnet either. But that doesn’t mean it has no magnetic field, or no electric field. And that magnetic field would have effects on GCR’s trajectory, and their different electric charge would intereact with the plasma’s electric field too.
tallbloke (12:47:08) :
And that magnetic field would have effects on GCR’s trajectory, and their different electric charge would intereact with the plasma’s electric field too.
I don’t know what you are trying to say, but the compression regions that scatter GCRs do that by virtue of the tangled turbulent magnetic fields. There are no electric fields in the plasma.
Actually this post may be a possible climate link according to Nir Shaviv. He describes how our climate can be effected by our solar system’s movement through the spiral galactic clouds/fluff (arms)… interesting stuff. He briefs on it in Henrik Svensmark’s youtube video.
I’m not a scientist but am fascinated by science. Can anyone discuss what has allowed these two tiny spacecrafts to exceed their life expectancy so spectacularly and when will they enter interstellar space.? Why has the extreme cold not affected their ability to transmit the data we still receive from them.
They are to me as a lay person observer, a marvel of mans achievement. As someone stated, money well spent.
Leif Svalgaard (11:39:36) :
“The magnetic fields in space are caused by dynamo processes where electrically neutral [but conducting] plasma moves across existing magnetic fields, creating currents that amplify the magnetic field and keeps them from dissipating..”
Yes but what causes the existing magnetic fields?
It is likely as we move through patches of plasma, whatever differences create double layers where high potential energies build up. No reason to think these double layers are static in any sense. Due to inherent instabilities why wouldn’t we expect something like pulses of avalanche currents which in turn effect the solar magnetic field, solar wind and energies that reach the earth. I think it is highly possible these plasm patches ultimately effect our the earth’s energy inputs and thus climates.
Doug in Seattle (10:41:27) :
At 6000 degrees I certainly hope our sun’s magnetic field is able to push it aside or otherwise deflect it’s effects. Or perhaps it already is?
Steve (12:36:47) :
@ur momisugly 6000 deg C its great that its a distance away but we are still going to get some effect – a bit more than co2, I’d wager.
Temperature in a gas effectively represents the speed of the atoms / molecules. The higher the temperature, the faster they go. This gas is extremely tenuous – presumably previously undetectable from its thermal radiation else we would have known more about it!
The gas at the surface of the sun is at a temperature of around 6000 C, and there’s a lot of it, so we feel the radiation from it; whereas gas in the corona, in the space around and fairly close to the sun, can reach a million degrees or so. It’s also pretty tenuous so we don’t really feel much thermal effect from that, though that’s also because as it’s so much hotter, the peak wavelength it emits at is a much shorter wavelength.
Don’t forget the obscene, war-like message in 55 languages attached to the Voyager craft, on a 33 1/3 r.pm. phonograph record (whatever that might be!)
Once a sentient life-form (hopefully not carbon-based) deciphers the message, and concludes that the human race is a clear and present danger to the Universe, then look out!
Interesting. This means that the majority of the Kuiper belt is outside the heliopause and located in interstellar space. This also means that the orbits of the known dwarf planets Eris, Sedna, Orcus, Quaoar, 2007-OR, Haumea and Makemake are in interstellar space. I wonder if there any plans to visit any of these plutoids?
Wow! Great discussion here. I’m learning a lot. I find it incredible that the Voyagers are still working after all of this time, and that they are “almost” into interstellar space. Hope they don’t malfunction once they get into all of the magnetic fields they encounter.
Anthony points out to John that this may have nothing to do with climate.
But let’s think for a moment. Tens to hundred of thousands of years for the solar system to move from one “fluff” cloud to the next? How sure are we that Milankovitch cycles are totally determinant of the current roughly 100,000 year — with smaller warmings occuring on intervals measured in tens of thousands of years — warm episode periodicity?
And what if Leif Svalgaard is correct in the comments in this post that:
====
Leif Svalgaard (10:28:05) :
“”” 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 “””
I don’t think this is correct. Cosmic rays are scattered away from the inner solar system by compression regions in the solar wind including the big one at the edge of the heliosphere, so I think that a more compressed heliosphere would mean less cosmic rays. Also, think of the opposite scenario: slowly take away the solar wind until in the end there is no heliosphere. That would IMHO lead to an increase in cosmic rays.
====
That would correlate with this being a time period of low cosmic rays — which according to Henrik Svensmark’s theory of Cosmoclimatology would lead to fewer low clouds and more warming. That is, the current Holocene warm period may in fact be correlated with passing through the current “fluff” cloud!
Over to you Henrik… (Merry Christmas and I hope you’ve recovered now and able to comment somewhere soon on the “fluff” discovery.)
There is a project that could give us fast interplanetary drives (days to weeks) and, with a bit of luck, interstellar travel drives. Woodward, Mach and Breakthrough Propulsion
For the 80+years of life there are solutions near at hand (Rapamicin, Sirtuins for example). There are people like Aubrey deGrey working on this problem.
I bet you know that science is not settled on these.
Jim Steele (13:05:09) :
Yes but what causes the existing magnetic fields?
They have always been there.
But from information in past posts on this site, I no longer subscribe to Nature!
John (10:09:06):
Interesting, but how does this have any bearing on our climate and ice age cycle?
REPLY: Why does it have to? Science for its own sake is enough don’t you think? – A
———————————-
I can understand the confusion as I have read the first post from Anthony when linked to a month or so back. By the way Anthony did you feel you would end up focusing mainly on AGW when you first started your blog?
———————————-
John, read the top 2 lines at the top of this page.
“Watts Up With That?
Commentary on puzzling things in life, nature, science, weather, climate change, technology, and recent news by Anthony Watts”
Leif Svalgaard (12:52:08) :
the compression regions that scatter GCRs do that by virtue of the tangled turbulent magnetic fields. There are no electric fields in the plasma.
So this wikipedia entry is incorrect?
http://en.wikipedia.org/wiki/Electric_field
“the electric and magnetic fields are not completely separate phenomena; what one observer perceives as an electric field, another observer in a different frame of reference perceives as a mixture of electric and magnetic fields. For this reason, one speaks of electromagnetism or electromagnetic fields.
John (10:09:06):
Interesting, but how does this have any bearing on our climate and ice age cycle?
__________________
It seems your question sparked some good comments. Thanks for asking.
“Voyager data show that the Fluff is much more strongly magnetized than anyone had previously suspected—between 4 and 5 microgauss*,”
To Leif Svalgaard: Would “anyone” include Hannes Alfven and Christian Birkeland?
Leif Svalgaard (10:28:05) :
Now we have 2 variables. At a time of increasing pressure on the heliosphere and decreasing output of Solar Wind, there should be less distance for the GCR’s to travel to reach the Inner Solar System.
Conversely, at a time of decreased pressure on the heliosphere and increased output of Solar WInd, we have a much larger distance for the GCR’s to travel to reach the Inner Solar System.
If both the pressure from the outside and the pressure from the inside wax and wan at the same time, there would be no change, from the Terrestrial viewpoint.
I’m being crude here, but the test would be for a given output of Solar Wind in times of more and less external pressure on the heliosphere as measured in neutron counts. We already know that chaging the Solar Wind output changes the GCR count.
If there is no difference attributable to the variance of external pressure, poof goes the hypothesis.
Very interesting stuff. I’d love to launch a few more probes to examine the Fluff and the Heliosheath. But the problem is that NASA has had their budget reduced and redirected to poor-utility programs. We should build a few probes with solar sails and fire them in different directions.
When I’m President, you can count on it!
The origin of the magnetic cloud is of supreme interest, remnant of the big bang or perhaps the waste product of a black hole?.
I would like to know how does it maintain a 6000C temperature with no apparent heat source?
This means that the “Bussard ramjet’ is a winner then.
tallbloke (14:44:45) :
So this wikipedia entry is incorrect?
“the electric and magnetic fields are not completely separate phenomena; what one observer perceives as an electric field, another observer in a different frame of reference perceives as a mixture of electric and magnetic fields. For this reason, one speaks of electromagnetism or electromagnetic fields.”
No, but must be interpreted correctly. The solar wind has a magnetic field B and speed V relative to the Earth, so the Earth sees an electric field E = B x V. An observer moving with the solar wind has V = 0 and thus sees E = 0. The correct statement is that ‘there is no electric field in the rest frame of the solar wind plasma’. So there is no electric current flowing in the solar wind as a result of this zero electric field. This is intuitively trivial to understand: the conductivity is almost infinite [the wind is so thin that a charge has to traverse many millions of km to meet another one]. So, if you had a collection of positive charges at point A and a collection of negative charges at point B, there will be a very strong [10^40 times the strength of gravity] electric field between them and they would attract each other with tremendous force and accelerate towards each other at enormous speed and short out the field.
lowercasefred (14:55:31) :
To Leif Svalgaard: Would “anyone” include Hannes Alfven and Christian Birkeland?
Alfven would not be surprised. Birkeland would have no idea what we are talking about.
rbateman (15:07:50) :
We already know that chaging the Solar Wind output changes the GCR count.
We do not know that, or rather: it is not that simple. The cosmic ray count is not determined by the solar wind speed or density or magnetic field [all of these have small second order effects only because a cosmic ray never collides with any of the solar wind particles]. What scatters cosmic rays are tangled magnetic fields: The particles spiral along field lines so their direction of movement changes all the time. If the field line also wiggles in space [turbulence] the direction changes even more and if the field strength changes, the spiral radius also changes. All of these changes mean that there is a fair chance the the final direction would be directed out of the solar system, hence decreasing the GCR flux.
So, the question now is: ‘how do we get tangled magnetic fields. The somewhat surprising answer is that solar rotation is large responsible. Imagine that one side of the sun emits solar wind at high speed and the other side emits a wind of low speed [e.g. a big equatorial coronal hole on one side]. Now, imagine a stationary observer [e.g. on Jupiter – that moves very slowly (12 years to go around compared to 25 days for solar rotation]. She would see fast solar wind coming towards her for two weeks and slow solar wind coming towards her for the next two weeks, followed by two weeks of fast, then two more weeks of slow wind, etc. So, the solar wind in a given fixed direction has different speeds over time, alternating between fast and slow. The fast wind would then catch up and run into the slower wind. The magnetic field is frozen onto the plasma so even though the particles never collide the magnetic field gives the plasma a fluid-like property, so that the fats solar wind compresses the slower wind ahead and produces a region of compression [followed by a region of rarefaction, of course]. Because the wind speed is not constant but varies a bit from place to place and from time to time, those compression regions get tangled and turbulent, thus creating a magnetic mirror that deflects the GCRs. As the Sun keeps rotating there will be several such mirrors between the Sun and the heliosphere, like 20-50 of them. Collectively they screen out GCRs. It doesn’t really matter [within reason] how strong the magnetic field is, it is enough that it is tangled a lot. Another process that also serves to produce such mirrors is the propagation of CMEs away from the Sun.
So where does the solar cycle variation come in? The coronal holes and the CMEs have a change in latitudes over the cycle. That means that at solar maximum there are mirrors all over the place [at all latitudes], while at solar minimum the mirrors [and there is also fewer of them] tend to occur at low latitudes, so the only affect GCRs coming in near the equatorial plane. The polar holes at solar minimum do not produce mirrors because there is no slow solar wind up there to slam into.
Once you grasp the grand picture it all makes sense and a lot of things fall into place. Kinda like plate tectonics making sense of geology.