Nano, a prefix meaning "dwarf" in Greek, also means one billionth. A nanometer is therefore one billionth of a meter. To provide a sense of scale, here are the measurements of some readily visible objects.
• The period at the end of this sentence is almost 500,000 nanometers in diameter.
• A penny is about 19,000,000 nanometers wide.
• A basketball is about 239,506,000 nanometers wide.
• Stanford basketball player Brooke Lopez is about 2,130,000,000 nanometers tall.