John, You wrote: > I notice that Jean Meeus is also particular about referring to JD as > Julian Day rather than Julian Date.
In a note Jean Meeus writes in his book: ------- In many books we read 'Julian Date' instead of 'Julian Day'. For us, a Julian date is a date in the Julian calendar, just as a Gregorian date refers to the Gregorian calendar. The JD has nothing to do with the Julian calendar. ------- I also think it is better to use Julian Day. Best wishes, Fer. Fer J. de Vries De Zonnewijzerkring mailto:[EMAIL PROTECTED] http://www.de-zonnewijzerkring.nl Home mailto:[EMAIL PROTECTED] http://www.iae.nl/users/ferdv/index-fer.htm Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: "John Hall" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, April 27, 2003 5:20 AM Subject: Re: Julian Date and UbiSol > Thank you Fer for such a clear and concise explanation. > > On Sunday, April 27, 2003, at 12:17 AM, fer j. de vries wrote: > > > > The difference is there is no difference. > > > > January 1st -4712 is the same as January 1st 4713 BC > > ( I think the 4173 in your message is a typo error) > > It certainly was - I only noticed it after the message had been posted. > > > > Atronomers count including the year 0 so the year before 1 is 0 and > > the year > > before that is -1. > > > > Historians count without the year 0 so the year before 1 is 1 BC and > > the > > year before that is 2 BC. > > > > Therefore we get two starting points for the Julian day: > > -4712 > > 4713 BC > > > > Jean Meeus uses the astronomical way because it's easier to calculate > > the JD > > for the Julian calendar. > > I notice that Jean Meeus is also particular about referring to JD as > Julian Day rather than Julian Date. > > By the way is the second edition of his book much changed from the > first edition ? Can anybody help with a comparison of the two editions. > > - > -
