An example of an everyday comparison used to give the scale of a scientific phenomenon:
"Disc galaxy [is] a type of galaxy in which a central bulge of cool stars (the nucleus) is surrounded by a flattened disc of material which includes stars, gas and dust…The proportions of the nucleus bulge and the flattened disc are roughly those of the yolk and the white of a fried egg, easy over; the thickness of the disc is about one-fifteenth of its diameter."
John Gribbin (1996) Companion to the Cosmos. (Ed., Mary Gribbin) Weidenfeld & Nicolson.
Read about quotidian comparisons
A document listing a wide range of examples of science analogies, similes, metaphors and other comparisons, drawn from diverse sources, can be downloaded using this link: 'Creative Comparisons: Making Science Familiar through Language. An illustrative catalogue of figurative comparisons and analogies for science concepts.'