This picture, published in Science by Ralph Lorenz of the University of Arizona and his colleagues, is a radar image of Titan, the largest moon of Saturn.

But the current view of cognitive science leans more toward a new image: memories are like emergent events summed out of many discrete, unmemory-like fragments stored in the brain.

It is an image worthy of a science fiction film: a rainbow, photographed in the middle of the night, glimmers in the foreground while behind it a brilliant star rises above the horizon.