Longitude and timezones

Today in class we talked about longitude and timezones. Longitude is  angular distance on the earth's surface, measured east or west from the PrimeMeridian at Greenwich, England. The prime meridian has a degrees of 0 degrees. Also, we talked about the timezones such as if it were 7:00 am here in bel air it would be 7:00 in china because of the 12 hour difference. The lines of longitude run in a north- south direction and they are the farthest apart from the equator and meet at north poles. They are also known as meridians. I also learned that Eratosthenes made the first world map in 195 BCE.