The inventor of Galactus says:
I would have included no further information than a rough image of the Earth and its one moon. I see no wisdom in the eagerness to be found and approached by any intelligence with the ability to accomplish it from any sector of space. In the meetings between 'discoverers' and 'discoverees,' history has always given the advantage to the finders. In the case of the Jupiter (Pioneer) plaque, I feel that a tremendous issue was thoughtlessly taken out of the world forum by a few individuals who have marked a clear trail to our door.
My point is, who will come a-knocking -- the trader or the tiger?