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Fraser
2005-Mar-04, 05:43 PM
SUMMARY: Scientists are fairly certain that the Earth went through a snowball glaciation 600-800 million years ago, when the entire planet was locked in snow and ice. One new theory to explain this extreme cooling is the possibility that the Solar System passed through an interstellar cloud of dust and gas, which obscured the light from the Sun. Even if the cloud wasn't thick enough to obscure light from the Sun, it could have enabled charged particles to pass into the Earth's atmosphere and destroy the ozone layer. These clouds are huge, and it would take the Solar System 500,000 years to pass through one.

View full article (http://www.universetoday.com/am/publish/clouds_space_cooled_earth.html)

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Guest
2005-Mar-04, 06:03 PM
It seems to me that this article is highly speculative at best. First you would need a large enough dust cloud with just the right properties, then a breakdown of the ozone layer and then cooling as a result of that. The magnetic pole reversal part I am not buying as there was a recent study that showed the upper atmosphere would screen out enough solar radiation to protect the planet during a pole reversal which is why pole reversals themselves do not cause mass extinctions.

antoniseb
2005-Mar-04, 06:34 PM
I also wonder how close a dense dust cloud could get to the sun without being cleared by solar wind and radiation pressure. It seems strange to me that anyone would think it could get in to the Earth's orbit.

400poundgorilla
2005-Mar-05, 01:04 AM
It seems to me that our solar systems path could take us through clouds of interstellar dust perhaps even thick ones, but yes, what about solar wind and radiation? Does this whole concept of a global freeze caused by passing thru a dust cloud seem any more believable than "The Day After Tomorrow?" No, but it might make for another good apocalyptic blockbuster movie. Popcorn anyone?