Karen of, age 10, of Bayside, NewJersey, for her question:

How is the correct time decided?

The correct time on a world wide basis is figured from the Prime Meridian, alias Longitude 0 degrees, which runs from pole to pole. The Prime Meridian is a man made line dividing the world into east and weft. It was decided upon at an International Convention in 1888.

The Greenwich Observatory near London has the job of figuring when the noon sun crosses the Prime Meridian. Timekeepers around the world check with Greenwich time: by radio and other means. The astronomers of Greenwich have been doing their exacting work since the days of King Charles II.