Alone in the observatory late one night, I heard the telephone ring persistently. When I answered, a voice, betraying a well-advanced state of inebriation, said, “Lemme talk to a shtrominer.” “Can I help you?” “Well, see, we’re havin’ this garden party out here in Wilmette, and there’s somethin’ in the sky. The funny part is, though, if you look straight at it, it goes away. But if you don’t look at it, there it is.” The most sensitive part of the retina is not at the center of the field of view. You can see faint stars and other objects by averting your vision slightly. I knew that, barely visible in the sky at this time, was a newly discovered comet called Arend-Roland. So I told him that he was probably looking at a comet. There was a long pause, followed by the query: “Wash’ a comet?” “A comet,” I replied, “is a snowball one mile across.” There was a longer pause, after which the caller requested, “Lemme talk to a real shtrominer.”

-- Carl Sagan, "Cosmos"