or

Bouquets and Powderkegs

From out where the sun blends into the general starscape, a huge envelope of ice chunks — the Oort Cloud — encloses the sun’s entire planetary system. Perhaps looking like ice itself, an object glides into the cloud from interstellar space directing short radio pulses toward Earth. Our land- and space-based telescopes swivel toward the data stream generated by this self-propelled comet. Arecibo listens from its tropical valley in Puerto Rico. The concise message announces simply, “We are coming.”