From: Damien Broderick (thespike@earthlink.net)
Date: Tue Jan 07 2003 - 11:44:57 MST
http://science.nasa.gov/headlines/y2003/06jan_bubble.htm?list730571
< The Local Bubble was discovered gradually in the 1970's and 1980's.
Optical and radio astronomers looked carefully for interstellar gas in our
part of the galaxy, but couldn't find much in Earth's neighborhood.
Furthermore, there seemed to be a pileup of gas--like the shell of a
bubble--about 150 light years away. Meanwhile, x-ray astronomers were
getting their first look at the sky using orbiting satellites, which
revealed a million-degree x-ray glow coming from all directions. "We
eventually realized that the solar system was inside a hot, vacuous bubble,"
says Hurwitz.
[...]
During the past few million years, wispy filaments of interstellar gas have
drifted into the Local Bubble. Our solar system is immersed in one of those
filaments--the "local fluff," a relatively cool (7000 K) cloud containing
0.1 atoms per cubic centimeter. By galactic standards, the local fluff is
not very substantial. It has little effect on Earth because the solar wind
and the Sun's magnetic field are able to hold the wispy cloud at bay.
There are, however, denser clouds out there. The Sco-Cen complex, for
instance, is sending a stream of interstellar "cloudlets" in our direction.
"Some of those cloudlets might be hundreds of times denser than the local
fluff," says Priscilla Frisch, an astrophysicist at the University of
Chicago who studies the local interstellar medium. "If we ran into one, it
would compress the Sun's magnetic field and allow more cosmic rays to
penetrate the inner solar system, with unknown effects on climate and life."
>
and so on. Always some damn thing.
Damien Broderick
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