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Rayleigh scattering (named after the British physicist Lord Rayleigh) is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light, which may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering is a function of the electric polarizability of the particles.
Rayleigh scattering of sunlight in the atmosphere causes diffuse sky radiation, which is the reason for the blue color of the sky and the yellow tone of the sun itself.
The strong wavelength dependence of the scattering (~λ−4) means that shorter (blue) wavelengths are scattered more strongly than longer (red) wavelengths. This results in the observation of indirect blue light coming from all regions of the sky. Rayleigh scattering is a good approximation to the manner in which light scattering occurs within various media for which scattering particles have a small size parameter.
ESA sees stardust storms heading for Solar System
Date Released: Monday, August 18, 2003
Source: Artemis Society
Until ten years ago, most astronomers did not believe stardust could enter our Solar System. Then ESA's Ulysses spaceprobe discovered minute stardust particles leaking through the Sun's magnetic shield, into the realm of Earth and the other planets. Now, the same spaceprobe has shown that a flood of dusty particles is heading our way.
What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001.
Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun's magnetic poles have only rotated at halfway and are now more or less lying sideways along the Sun's equator. This weaker configuration of the magnetic shield is letting in two to three times more stardust than at the end of the 1990s. Moreover, this influx could increase by as much as ten times until the end of the current solar cycle in 2012.
Is the solar system entering a nearby interstellar cloud
Vidal-Madjar, A.; Laurent, C.; Bruston, P.; Audouze, J.
AA(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AB(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AC(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AD(Meudon Observatoire, Hauts-de-Seine; Paris XI, Universite, Orsay, Essonne, France)
Astrophysical Journal, Part 1, vol. 223, July 15, 1978, p. 589-600. (ApJ Homepage)
ASTRONOMICAL MODELS, DEUTERIUM, HYDROGEN ATOMS, INTERSTELLAR GAS, SOLAR SYSTEM, ABUNDANCE, EARLY STARS, GAS DENSITY, INTERSTELLAR EXTINCTION
Observational arguments in favor of such a cloud are presented, and implications of the presence of a nearby cloud are discussed, including possible changes in terrestrial climate. It is suggested that the postulated interstellar cloud should encounter the solar system at some unspecified time in the 'near' future and might have a drastic influence on terrestrial climate in the next 10,000 years.
Surprise In Earth's Upper Atmosphere: Mode Of Energy Transfer From The Solar Wind
"Its like something else is heating the atmosphere besides the sun. This discovery is like finding it got hotter when the sun went down," said Larry Lyons, UCLA professor of atmospheric and oceanic sciences and a co-author of the research, which is in press in two companion papers in the Journal of Geophysical Research.
"We all have thought for our entire careers — I learned it as a graduate student — that this energy transfer rate is primarily controlled by the direction of the interplanetary magnetic field," Lyons said. "The closer to southward-pointing the magnetic field is, the stronger the energy transfer rate is, and the stronger the magnetic field is in that direction. If it is both southward and big, the energy transfer rate is even bigger."
However, Lyons, Kim and their colleagues analyzed radar data that measure the strength of the interaction by measuring flows in the ionosphere, the part of Earth's upper atmosphere ionized by solar radiation. The results surprised them.
"Any space physicist, including me, would have said a year ago there could not be substorms when the interplanetary magnetic field was staying northward, but that's wrong," Lyons said. "Generally, it's correct, but when you have a fluctuating interplanetary magnetic field, you can have substorms going off once per hour.
"Heejeong used detailed statistical analysis to prove this phenomenon is real. Convection in the magnetosphere and ionosphere can be strongly driven by these fluctuations, independent of the direction of the interplanetary magnetic field."
Ribbon at Edge of Our Solar System: Will the Sun Enter a Million-Degree Cloud of Interstellar Gas?
ScienceDaily (May 24, 2010) — Is the Sun going to enter a million-degree galactic cloud of interstellar gas soon?
Scientists from the Space Research Centre of the Polish Academy of Sciences, Los Alamos National Laboratory, Southwest Research Institute, and Boston University suggest that the ribbon of enhanced emissions of energetic neutral atoms, discovered last year by the NASA Small Explorer satellite IBEX, could be explained by a geometric effect coming up because of the approach of the Sun to the boundary between the Local Cloud of interstellar gas and another cloud of a very hot gas called the Local Bubble. If this hypothesis is correct, IBEX is catching matter from a hot neighboring interstellar cloud, which the Sun might enter in a hundred years.
The Sun traveling through the Galaxy happens to cross at the present time a blob of gas about ten light-years across, with a temperature of 6-7 thousand degrees kelvin. This so-called Local Interstellar Cloud is immersed in a much larger expanse of a million-degree hot gas, named the Local Bubble. The energetic neutral atoms (ENA) are generated by charge exchange at the interface between the two gaseous media. ENA can be observed provided the Sun is close enough to the interface. The apparent Ribbon of ENA discovered by the IBEX satellite can be explained by a geometric effect: one observes many more ENA by looking along a line-of-sight almost tangent to the interface than by looking in the perpendicular direction. (Credit: SRC/Tentaris,ACh/Maciej Frolow)
Our solar system may be headed for an encounter with a dense cloud of interstellar matter
Our solar system may be headed for an encounter with a dense cloud of interstellar matter–gas and dust–that could have substantial implications for our solar systems interplanetary environment, according to University of Chicago astrophysicist Priscilla Frisch. The good news is that it probably won’t happen for 50,000 years. Frisch presented the results of her research Monday, June 10, at the meeting of the American Astronomical Society in Madison, Wisc.
Frisch has been investigating the interstellar gas in the local neighborhood of our solar system, which is called the Local Interstellar Medium (LISM). This interstellar gas is within 100 light years of the Sun. The Sun has a trajectory through space, and for most of the last five million years, said Frisch, it has been moving through a region of space between the spiral arms of the Milky Way galaxy that is almost devoid of matter. Only recently, within the last few thousand years, she estimates, the Sun has been traveling through a relatively low-density interstellar cloud.
“This cloud, although low density on average, has a tremendous amount of structure to it,” Frisch said. “And it is not inconsistent with our data that the Sun may eventually encounter a portion of the cloud that is a million times denser than what we’re in now.”
Frisch believes the interstellar cloud through which we’re traveling is a relatively narrow band of dust and gas that lies in a superbubble shell expanding outward from an active star-formation region called the Scorpius-Centaurus Association. “When this superbubble expanded around these stars, it expanded much farther into the region of our galaxy between the spiral arms, where our sun lies, because the density is very low,” Frisch said. “It didn’t expand very far in the direction parallel to the spiral arms because it ran into very dense molecular clouds.”
A number of independent experts have discussed their concerns regarding the burning of radioactive waste in Japan since this activity will simply result in the radioactive contamination moving to other locations in Japan and significantly to North America and elsewhere. The burning has taken a very ominous turn for the residents of Japan as the Japanese Ministry of Environment has decided the radioactive ashes can be buried. Until now they have been sitting around waiting for a policy on their disposal.
From NHK News (8/28/2011): [Japanese characters removed] "Regarding the ashes after burning the disaster debris and regular household garbage contaminated with radioactive materials, the Ministry of the Environment has decided on a policy that will allow the burial of ashes that exceed 8,000 becquerels/kg of radioactive cesium, as long as there are countermeasures in place to prevent the leakage into the ground water.
Radioactive cesium exceeding 8,000 becquerels/kg has been detected from the ashes from burning the regular household garbage in Kanto and Tohoku regions. The Ministry of the Environment has decided to apply the same rule as the disaster debris and allow the ashes to be buried.
The disabling of the cooling systems forced them to pour vast quantities of seawater onto the problem reactors. Salt is sodium chloride, and when the dissolved chlorine was bombarded with neutrons from the exposed fuel rods, it was transformed it into an unstable form of sulfur - sulfur-35. As the seawater boiled to steam, it was vented off to prevent explosions. That steam took with it the newly created sulfur-35.
Just how bad were things at Fukushima? So far, painting a clear picture is difficult, as all we know for sure is how much radioactivity has been spotted at specific sites of contamination. Now, researchers have put together a largely independent estimate of the neutron flux that occurred during the meltdown, pieced together from an unlikely source: a long-term monitoring experiment being run in San Diego. Nearly two weeks after the earthquake and tsunami, some equipment on the Scripps Pier picked up a surge in radioactive sulfur that has enabled a rough estimate of the radioactivity released at Fukushima.
Normally, a radioactive form of sulfur (S-35) is produced in the atmosphere when cosmic rays react with argon in the upper atmosphere. In San Diego, this produces fairly steady levels of S-35O2 and S-35O4-2, except during seasonal periods when winds shift more material down from the stratosphere, where cosmic ray exposures are highest. But, on March 23rd of this year, levels of radioactive sulfur suddenly spiked, reaching over seven times normal background by the end of the month. With no indications of an atmospheric disturbance, the researchers focused across the Pacific, on Fukushima.
S-35 can also be formed by neutron bombardment of Cl-35; that isotope is normally present in sea water, which was dumped on the ailing reactors in copious quantities. As the seawater reached the reactor core, it would receive a healthy dose of neutrons. A decent fraction of the S-35 that formed would then boil off with the water, reacting with oxygen and forming sulfates. The uncharged form would fall out of the atmosphere over the next few days as a solid, but the S-35O4-2 could potentially stay airborne for an entire trip across the Pacific. By modeling the flow of winds prevalent at the time of the reactor meltdown, the authors were able to demonstrate that some portion of the air that was reaching San Diego probably had originated above the reactor site.
Originally posted by onthelookout
reply to post by Wertwog
Here's a big ole' "what if"...cosmic dust coming in...settling in and affecting our plants, health (mental/physical), water, etc. as well as stirring up trouble with weather or volcanoes and in turn we're seeing the culmination of all of it with the Rayleigh scattering (volcano/fires/cosmic dust, etc.)?
But according to a new study, electric ash from the Eyjafjallajökull volcano was found a record 745 miles (1,200 kilometers) away from the eruption.
At that distance, it wasn't energy from the eruption itself that charged the ash, said study co-author Giles Harrison, a meteorologist at the University of Reading in the U.K. Based on the average size and shape of particles in the ash, "any initial charging that occurred would have decayed away many times over." In fact, ash from deep in the volcanic plume was still charged 32 hours after being spewed from the Iceland peak, which suggests that the charge was self-renewing, the scientists say.
The discovery means that many volcanic ash plumes might be electrified, which could have implications for the air-travel industry.
While grains of stardust are very small, about one hundredth the diameter of a human hair, they do not directly influence the planets of the Solar System. However, the dust particles move very fast, and produce large numbers of fragments when they impact asteroids or comets. It is therefore conceivable that an increase in the amount of interstellar dust in the Solar System will create more cosmic dust by collisions with asteroids and comets. We know from the measurements by high-flying aircraft that 40 000 tonnes dust from asteroids and comets enters the Earth's atmosphere each year. It is possible that the increase of stardust in the Solar System will influence the amount of extraterrestrial material that rains down to Earth.
Originally posted by onthelookout
But, having said that - it isn't a bad idea to get some feedback from professionals who may have more information to help with the discussion - so thanks for that suggestion.
Originally posted by onthelookout
So while stardust itself would be too small to do of anything to interest to the planet, it does aid in increasing the amount of other extraterrestrial material that we see raining down on our planet. I think this particular article was saying it would be increasing from 2005 onward. So that is something to look into. What would asteroid & comet dust mostly consist of? I'd like to see if/what any studies regarding the effects (is that right? or affects...I never get it straight) the material have on us & our planet.