Mega is a prefix that means large. It starts out words such as megabytes and megalopolis.
A megabyte is about a million bytes. When computers first came out, most of us considered a megabyte of memory more than we could ever use. Now we generally want at least one gigabyte (1,000 megabytes.) Some people say that soon we'll want even more, so we may decide on storage of one terabyte, or 1,000 gigabytes.
Megalopolis comes from two Greek words meaning “great city.” In modern terms Webster's says it is “an extensive, heavily populated continuously urban area, including any number of cities.”
Below are photos of two megalopolises taken by NASA, our country's space agency. The top photo shows the Eastern Seaboard of the United States, which contains a chain of cities from Boston in the north to Washington, DC, in the south. The bottom photo shows a string of cities on the southern tip of Honshu, a major island of Japan.
If you’re wondering how many bytes of memory it took to store these photos, I’m afraid I haven't a clue!
NASA photo courtesy of Wikipedia