WP 34S conversion error
01-07-2015, 07:34 PM
Post: #14
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: WP 34S conversion error
(01-05-2015 10:13 PM)Didier Lachieze Wrote:  I'm not an astronomer and this may not fully answer your question but here is a hint about usage of Julian dates in astronomy:

Caveat!
There are two different things that should not get confused:

On the one hand there is the Julian calendar. Unlike the Gregorian calendar that is used today in most parts of the world, every 4th year is a leap year. According to the Julian calendar, Christmas day is today, on 7 January. In the Julian calendar, a year on average has 365,25 days.

On the other hand there are Julian day numbers. Unlike the usual notation with day, month and year, a certain point in time here is defined by a single number, which allows easy calculations by simple addition/subtraction. These Julian day numbers usually are based on the Gregorian calendar which on average has 365,2425 days per year.

Walter wondered why the light year was defined on a year being 365,25 days (i.e. like it was in the now mostly defunct Julian calendar) and not 365,2425 days (like in the Gregorian calendar) or others, e.g. 365,2422 days (= 1 tropical year).

Dieter
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 Messages In This Thread WP 34S conversion error - Peter Van Roy - 10-09-2014, 06:01 PM RE: WP 34S conversion error - Paul Dale - 10-09-2014, 09:37 PM RE: WP 34S conversion error - Gerson W. Barbosa - 10-10-2014, 03:08 AM RE: WP 34S conversion error - walter b - 10-10-2014, 08:27 AM RE: WP 34S conversion error - Dieter - 10-10-2014, 05:57 AM RE: WP 34S conversion error - walter b - 10-10-2014, 08:23 AM RE: WP 34S conversion error - Marcus von Cube - 10-10-2014, 02:09 PM RE: WP 34S conversion error - Dieter - 10-10-2014, 07:04 PM RE: WP 34S conversion error - walter b - 10-10-2014, 07:44 PM RE: WP 34S conversion error - walter b - 12-09-2014, 07:03 AM RE: WP 34S conversion error - walter b - 01-05-2015, 08:13 PM RE: WP 34S conversion error - Didier Lachieze - 01-05-2015, 10:13 PM RE: WP 34S conversion error - Dieter - 01-07-2015 07:34 PM RE: WP 34S conversion error - Wolfgang - 11-11-2014, 10:30 PM

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