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Originally posted by grover
yes mister know-it-all...I bow down to your superior knowledge... now would you please contact the academy of science and inform them about how wrong they all are and how right you are.
June 9, 1996 Press Contact: Steve Koppes
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 system’s 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.”
The solar wind–the flux of charged particles streaming from the Sun’s corona–protects the Earth from direct interaction with the interstellar medium by enveloping the Earth and all the planets in the heliosphere, the region of influence of the solar wind. The heliosphere currently extends 100 times farther from the Sun than the distance between Earth and the Sun. “We think the heliosphere might have been much larger before we entered the interstellar cloud,” said Frisch, “but that’s something we can’t say for sure.”
But if the solar system encountered the much denser cloud, Frisch estimates that the heliosphere could be compressed to within one or two astronomical units of the Sun, not much greater than the Earth’s distance from the Sun. “There would be dramatic effects on the inner solar system,” said Frisch. “It would immediately change the whole interaction between the solar wind and the interstellar medium.” Researchers have predicted increases in the cosmic-ray flux, changes in the Earth’s magnetosphere, the chemistry of the atmosphere and perhaps even the terrestrial climate.
see full issue: January-February 2000 Volume: 88 Number: 1 Page: 52
DOI: 10.1511/2000.1.52Other Formats: PDF
The Galactic Environment of the Sun
A Changing Galactic Environment
We do not know whether the interstellar cloud complex flowing past the sun is a homogeneous structure. On the basis of more distant interstellar clouds, it's quite possible that the Local Interstellar Cloud contains relatively small structures (perhaps 100 to 10,000 AU across) with very high densities (more than 1,000 particles per cubic centimeter). If our solar system should pass through such a dense cloud fragment, the dimensions of the heliosphere would change dramatically.
My colleague Gary Zank at the University of Delaware and I have recently modeled the changes that might take place should the heliosphere encounter a dense interstellar cloud. If the density of the Local Interstellar Cloud increased to 10 particles per cubic centimeter, the heliosphere would contract to a radius of about 15 AU and the heliopause would become unstable (oscillating in and out of existence). The density of interstellar hydrogen at 1 AU would increase to about 2 atoms per cubic centimeter and dramatically alter the interplanetary environment of the earth. (By comparison, virtually all of the interstellar hydrogen is ionized before it gets to the earth's orbit under current conditions.) A more severe scenario—say a cloud with a density of 1,000 atoms per cubic centimeter—would alter heliosphere physics entirely and probably contract the heliosphere to within a few AU of the sun. Planets such as Saturn, Uranus, Neptune and Pluto (all of which are outside 9 AU) would be fully exposed to the flux of interstellar neutrals. Interstellar gas would overwhelm the solar wind at 1 AU. These simulations suggest that, to a certain extent, the solar wind acts to "protect" the inner planets from certain types of changes in the local galactic environment.
The Local Fluff
The composition of the interior of the Local Bubble is not uniform. Clouds of low-density gas float inside the Local Bubble. The solar system is currently passing through such a cloud, known as The Local Fluff, or The Local Interstellar Cloud. The cloud is about 30 light years in length, and it mainly contains hydrogen and helium gasses. A few of our closer stellar companions, including the star Altair, are also passing through this cloud. The cloud appears to emanate from a star-forming region, known as the Sco-Cen OB Association2, in the Loop 1 bubble. It is expected that our Sun will leave this cloud in the next 10,000 to 20,000 years. Much of the heavier matter (ie, heavier than hydrogen) from the cloud actually enters the solar system environment - we normally pass through a concentrated flow of interstellar gas from this cloud each November.
What it Means to Us here on Earth
As our Sun travels on its 230 million-year circuit of the Milky Way, it passes through regions of very dense clouds and regions almost completely devoid of interstellar gas. Thanks to our current transit through the Local Bubble, we have a magnificent opportunity to view our galactic neighbourhood in great detail. Conversely, if we were passing through an interstellar cloud, we would see practically nothing in the sky at night3. A low density interstellar environment is also good for life on Earth, as it enables the Sun to cast its protection cover, the Heliosphere, out to great distances4 beyond the solar system, thus deflecting and repelling dangerous charged particles. However, the Heliosphere is highly sensitive to the density of interstellar gas, and it could fail almost completely if the Sun passed though a dense cloud of gas, exposing the Earth to massive amounts of harmful radiation. There is some evidence to suggest that the Earth has experienced mass extinctions caused by interstellar explosions in the past - perhaps caused because we were in a dense cloud when the effects of a supernova passed us by.
Originally posted by mrsdudara
Back on subject PLEASE!!!!
Originally posted by mrsdudara
First of all......Has there been an ebola virus that is airborne, and could really knock out 90% of the population?
Originally posted by mrsdudara
Second....Seriously, does he really expect to be able to continue living with the casual comforts of this century with 90% of the population gone? Im thinking this guy is JUST smart enough to be dangerous.
Originally posted by Muaddib
You are right, it is in part my fault for getting in the habit of responding to people like grover.
Airborne ebola transmission has been demonstrated between monkeys in controlled experiments, but there have been no cases of human to human airborne transmission, that i know of. There has to be contact between fluids, or fluid to skin contact for people to catch the virus.