Russ Steele
Science@NASA has the story: Voyager Makes an Interstellar Discovery
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.The full story here, but this is the part that caught my eye, highlighted below.
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.
If cosmic rays turn out to be major modulator of cloud formation a few extra could change the climate.
Update (12-25-09): Heliogenic Climate Change blog has more insight into the impact of the solar system moving through the spiral arms of the galaxy:
Physicist Nir Shaviv has shown a correlation between the ice ages and the passing of the solar system through the spiral arms of the Milky Way galaxy, during which the number of cosmic rays reaching the Earth is substantially increased.
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