Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site umcp-cs.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!umcp-cs!mangoe From: mangoe@umcp-cs.UUCP (Charley Wingate) Newsgroups: net.sf-lovers,net.astro Subject: Re: visible civilization (real sources) Message-ID: <1128@umcp-cs.UUCP> Date: Tue, 6-Aug-85 20:44:06 EDT Article-I.D.: umcp-cs.1128 Posted: Tue Aug 6 20:44:06 1985 Date-Received: Fri, 9-Aug-85 02:21:24 EDT References: <1363@uwmacc.UUCP> Followup-To: net.astro Organization: U of Maryland, Computer Science Dept., College Park, MD Lines: 22 Xref: linus net.sf-lovers:8175 net.astro:768 [followups to net.astro, please] I knew I had sources somewhere.... In the May 1975 _Scientific American_ there is a nice article on searching for extraterrestrial intelligence by Sagan and Drake. A summary of their articles (or parts of it anyway): Arecibo Observatory, when transmitting, is at least a million times brighter than the sun. This signal can be detected by a similar receiver at a distance of about ten thousand light years. A number of other sites have similar capabilities. In the FM and VHF tv bands, the earth is quite bright. A receiver system to detect such signals was conceived of at the time of the article, to be called 'Cyclops'. Employing 1500 antennas of 100 meters each,it would be able to detect such signals out to several hundred lightyears. Such a system would not be beyond our current technology-- but it would be very expensive (~$10G). These observations do not rely on resolving the earth as a separate body. C Wingate