At 08:23 AM 9/10/2003 -0400, Tom wrote:
>I'm confused. Sound is created by a disturbance in the AIR which emanates
>from the source and is detected by our ears, or a microphone, etc. Since
>there is NO AIR in space, how does this 'sound wave' get to earth, and
>thus be detected by NASA?
This caught me for a moment as well, but if you think about it, sound waves
travel through a lot of things other than "air". Environmentalists
complain about low-frequency sound waves travelling through seawater and
affecting marine life and SONAR has been in use for decades. Geologists use
sound waves to identify rock formations deep underground.
While there is no "air" to speak of in outer space it isn't a complete
vacuum. The space around this particular black hole in the Perseus cluster
contains a fair amount of gas, which Chandra is able to "see". As I
understand it, the sound waves show up as ripples in the gas.
The science is quite fascinating. For more information and a picture, see
http://www1.msfc.nasa.gov/NEWSROOM/news/releases/2003/03-152.html
John
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