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by Carl Sagan

“Okay, let’s see if I can do another quick summary. I’ll do it in the simplest language. Please check if I’ve missed anything. We have an extremely strong, not very monochromatic signal. Immediately outside the bandpass of this signal there are no other frequencies reporting anything besides noise. The signal is linearly polarized, as if it’s being broadcast by a radio telescope. The signal is around nine gigahertz, near the minimum in the galactic radio noise background. It’s the right kind of frequency for anyone who wants to be heard over a big distance. We’ve confirmed sidereal motion of the source, so it’s moving as if it’s up there among the stars and not from some local transmitter. NORAD tells us that they don’t detect any satellites—ours or anybody else’s—that match the position of this source. Interferometry excludes a source in Earth orbit anyway. “Steve has now looked at the data outside the automated mode, and it doesn’t seem to be a program that somebody with a warped sense of humor put into the computer. The region of the sky we’re looking at includes Vega, which is an A-zero main sequence dwarf star. It’s not exactly like the Sun, but it’s only twenty-six light-years away, and it has the prototype stellar debris ring. There are no known planets, but there certainly could be planets we don’t know anything about around Vega. We’re setting up a proper motion study to see if the source is well behind our line of sight to Vega, and we should have an answer in—wh...