Since the early 1960's (possibly before) there has been an interest in listening to signals from outer space, with the idea that perhaps an intelligent race, similar to our own or possibly more advanced, just might be trying to communicate with us, or anyone else for that matter. Scientists have monitored the RF spectrum and have concluded that we and "they" would most likely choose one of the more "quiet" zones in the spectrum, and have chosen 1420 Mhz as a center zone, with a bandwidth of 2.5 Mhz. There are technical reasons behind this as well, but primarily it is "quiet" compared to the rest of the spectrum.
Wide band receivers using the Arecibo Radio Telescope located in Puerto Rico, gather hugh amounts of data, far in excess of what could be "looked at" even with the super computers of today. Examining such data as fast as it is collected, would require a super computer running 24 hours a day, and would never catch up. SETI engineers realized that there is a large group of amateurs in the world (not necessarily ham radio operators) who are also insterested in SETI, and want to be a "part of the action"! The data that is collected is divided into much smaller packets of information and via the internet, downloaded into thousands of home computers around the world. It is believed that this number of computers may approach (or exceed by now), 30,000. A special program to "number crunch" the data is a part of a special screen saver that you can also download and run. During "idle" times on your computer, the program built into the screen saver is activated and does the number crunching. As "packets" of data are analyzed, they are sent back to SETI as finished modules. IF a signal of importance is found, YOU will know about it, and so will SETI, and a means of confirming the results will be set into action. Finished modules sent back to SETI via the internet (when you connect) are replaced with new modules at the same time. The program logs how much time your CPU has used...etc..
As scientists look at the heavens, things are happening. For instance, 50, yes 50, planets have now been discovered orbiting stars, some as close as only 8 to 15 light years. Others are far beyond that, but new planets are being discovered at an increasing rate with advances in astromey, detection methods and such.
A light year is the distance light (or a radio signal) travels in one year. Light (and radio signals) travel at approximately 186,000 miles per second.
For more information about S.E.T.I., please visit these web sites:
http://www.setileague.org
http://www.setiathome.ssl.berkeley.edu/
http://www.ac6v.com (this site includes links to various sites, including SETI)
http://www.webcom.com/af9y (design for a helix antenna)
http://www.nrao.edu
http://www.bigear.org (the WOW signal. VERY Interesting Reading)
