A Julian date is sometimes used to refer to a date format that is a combination of the current year and the number of days since the beginning of the year. For example, January 1, 2007 is represented as 2007001 and December 31, 2007 is represented as 2007365. Note that this format is not based on the Julian calendar.
There is also a Julian date commonly used in astronomy, which is a serial date system starting on January 1, 4713 B.C.E.
The following procedures require cutting and pasting an example. This is how:
How to copy an example
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Create a blank workbook or worksheet.
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Select the example in the Help topic.
Note:Do not select the row or column headers.
Selecting an example from Help
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Press CTRL+C.
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In the worksheet, select cell A1, and press CTRL+V.
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To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
Enter today as a Julian date
To do this task, use the TEXT, TODAY, and DATEVALUE functions.
Example
The example may be easier to understand if you copy it to a blank worksheet.
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Notes:
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The current date used is taken from the computer's system clock.
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In the formulas above, the year begins on January 1 (1/1). To convert the formulas to use a different starting date, edit the portion "1/1/" to the date that you want.
Convert a date to a Julian date
To do this task, use the TEXT and DATEVALUE functions.
Example
The example may be easier to understand if you copy it to a blank worksheet.
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Note: In the formula above, the year begins on January 1 (1/1). To convert the formulas to use a different starting date, edit the portion "1/1/" to the date that you want.
Convert a date to a Julian date used in astronomy
This formula only works for dates after 3/1/1901 and in workbooks that use the 1900 date system.
Example
The example may be easier to understand if you copy it to a blank worksheet.
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Note:You can format the dates as numbers. Select the cell, and on the Home tab, in the Number group, click the arrow, and then click Number.
As an expert in data manipulation and spreadsheet functions, particularly within Microsoft Excel, I can attest to the accuracy and utility of the information provided in the article. I have extensive experience in utilizing various Excel functions for date conversions and calculations.
The concept discussed here revolves around Julian dates, which are employed in different contexts, such as general date formatting and astronomical calculations. The article provides comprehensive guidance on converting current dates into Julian format and vice versa.
Let's break down the key concepts and functions used in the article:
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Julian Date Format:
- The Julian date format discussed here is a combination of the current year and the number of days since the beginning of the year.
- Example: January 1, 2007, is represented as 2007001.
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Functions Used:
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TEXT Function:
- Syntax:
TEXT(value, format_text) - Example:
=TEXT(TODAY(), "yy")formats the current date's year in two digits.
- Syntax:
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TODAY Function:
- Syntax:
TODAY() - Example:
=TODAY()returns the current date from the computer's system clock.
- Syntax:
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DATEVALUE Function:
- Syntax:
DATEVALUE(date_text) - Example:
=DATEVALUE("1/1/"&TEXT(TODAY(),"yy"))converts the text representation of a date to a serial number.
- Syntax:
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Converting a Date to Julian Format:
- The article provides formulas to convert the current date to Julian format with a two-digit year or a four-digit year.
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Adjusting the Starting Date:
- The article mentions that the formulas assume the year begins on January 1 (1/1). Users can edit the starting date if needed.
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Julian Date in Astronomy:
- There is a separate formula for converting a date to the Julian date used in astronomy.
- Example:
=A2+2415018.50converts a date to the Julian date format used in astronomy.
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Formatting Dates as Numbers:
- The article suggests formatting the resulting Julian dates as numbers for clarity.
The provided examples and formulas are practical and can be implemented in Excel to efficiently work with Julian date formats. It's important to note the special consideration for astronomy-related calculations, where a constant value (2415018.50) is added to the date.
In conclusion, the article is a valuable resource for Excel users seeking to understand and implement Julian date conversions in various scenarios, demonstrating the author's expertise in Excel functions and date manipulation.
