Julian day

This has now become the standard system of Julian days.

A simple example is the calculation of the Julian day.

The idea was based on the Julian day currently used by astronomers.

For comparison, see the calculation of a Julian day number.

The integral part (its floor) gives the Julian day number.

Astronomers avoid this ambiguity by the use of the Julian day number.

This is much less practical with Julian days count.

The days in the numerators are calculated on a Julian day difference basis.

Herschel originated the use of the Julian day system in astronomy.

Almost 2.5 million Julian days have elapsed since the initial epoch.

The Julian day number can be calculated using the following formulas:

When this practice ended in 1925, it was decided to keep Julian days continuous with previous practice.

It can be considered to be based on the conversion between Julian day and the calendar date.

Because the starting point or reference epoch is so long ago, numbers in the Julian day can be quite large and cumbersome.

At times like that it feels as though we were living by the calendar astronomers sometimes use, by which today is the Julian day 2453737.

The algorithm is valid at least for all positive Julian Day Numbers.

That noon-to-noon day is counted as Julian day 0.

The Julian day number can be considered a very simple calendar, where its calendar date is just an integer.

The Julian day uniquely specifies a date without reference to its day, month, or year in any particular calendar.

Days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used.

In astronomy, the so-called Julian Day uses decimal days centered on noon.

Some scientists use the term julian day to mean the numerical day of the current year, where January 1 is defined as day 001.

For consistency, and to avoid having a 10-day discontinuity, astronomers use Julian Day when dealing with historical dates.

This applies for the Julian day or Unix Time.

Julian Dates are expressed as a Julian day number with a decimal fraction added.