Back to Home

General Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Misc. Topics | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Re: Radio Telescopes

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Jim on February 18, 2000 13:48:12 UTC

It`s true stars emit trillions of watts of electromagnetic radiation. It`s also true that radio waves have very long wavelengths which mostly range from less than a meter to 10 kilometers. Thus, they`re only a part of that electromagnetic energy at the long end, (in terms of wavelengths), of the electromagnetic spectrum. But only certain radio wavelengths would be useful for this type of communication. Wavelengths longer than about 30 cm can`t be used since the signal would be lost in the background radio noise from our galaxy. We also can`t use wavelengths much smaller than 1 cm because they`d be absorbed by our atmosphere. Therefore, only a certain range of wavelengths can be used. Within this communication range lies the 21-cm line of neutral hydrogen and the 18-cm line of OH. This interval between these two lines has been dubbed the 'water hole' because the combo of H and OH yields water. Water is the fundamental solvent in our life form so it only seems natural for similar water creatures to call out to each other at wavelengths in the water hole. But even a silicon creature would be familiar with the 21-cm line of hydrogen. Thus, they too might select wavelengths near the water hole. But such messages would have to be sent consisting of a pattern of pulses obviously designed by intelligent beings to distinguish it from natural radio sources emitted by nebulae and pulsars and so on. For ex., pulses counting off the 1st 12 prime nos. would do. Hope this helps.

Follow Ups:

Login to Post
Additional Information
Google
 
Web www.astronomy.net
DayNightLine
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2019 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins