What if There is Contact?

On August 15, 1977 the Ohio State University Observatory detected the signal seen above. It was found at the time that the source was not terrestrial and was moving with the background stars. The coordinates did not match any known solar-type star. This would have been called a valid SETI "contact" except for the fact that the signal did not repeat. This has become known as the "WOW" signal since one of the astronomers made that notation in the margin of the computer printout. (Courtesy: SETI)
At some point the SETI programs may be successful - some signal or other evidence of extraterrestrial intelligence may be discovered. What then? One can only imagine, and many science fiction and screen writers have described several alternatives. Scientists working on these projects have their own dreams of a rational process, which you can read at: SETI Institute

In brief, the discoverers should first make very sure their signal (or whatever) is indeed extraterrestrial, and presumably from outside our solar system. They should then notify other SETI teams for confirmation. If confirmed, the news is to be spread widely to the world. Formalism for a return message is still in development, presumably because there is no universal agreement on whether we should reply.

It may be noted that the first stage of this process were followed back in 1967, when radio astronomers at Cambridge University discovered a radio source emitting pulses at extremely well-spaced intervals, better than most clocks.

The "WOW" printout. (Courtesy: SETI)
For a while there was half-serious talk of "little green men", until three more such sources were found and the phenomenon was attributed to spinning neutron stars emitting searchlight-like radio beams. The rest of the scientific community however was not immediately informed of the positions of the additional pulsars. Many publications and a Nobel Prize followed, but no world-wide panic. These relics of supernovae are very interesting, but not nearly as much so as extraterrestrials would have been!