The Julian day starts at noon because they are interested in things that are visible at night .
Astronomers describe time as a number of days and a fraction of a day since noon January 1 , - 4712 Greenwich Mean Time .
The Julian day starts at noon because Astronomers are interested in things that are visible at night .
Astronomers describe time as a number of days and a fraction of a day since noon January 1 , - 4712 Greenwich Mean Time .