PHP Julian Calendar to Julian Day Conversion Tutorial

What are the Julian Calendar and Julian Day?

The Julian Calendar, established by Julius Caesar in 46 BC, has a year length of 365.25 days. The Julian Day, on the other hand, is a continuous date system commonly used in astronomy and historical research.

Why Do We Need the Conversion?

In many applications, users may need to convert Julian Calendar dates to Julian Day, especially when dealing with astronomical data or historical records. Some scientific computations and astronomical software rely on the conversion between these two calendars.

PHP Implementation for Julian Calendar to Julian Day Conversion

Let’s take a look at how to write a simple PHP function to convert Julian Calendar dates to Julian Day. Below is the sample code:

<span class="fun">function julianToJulianDay($year, $month, $day) { $a = floor((14 - $month) / 12); $y = $year + 4800 - $a; $m = $month + (12 * $a) - 3; return $day + floor((153 * $m + 2) / 5) + (365 * $y) + floor($y / 4) - floor($y / 100) + floor($y / 400) - 32045; } // Example $julianYear = 2023; $julianMonth = 10; $julianDay = 10; $julianDayNumber = julianToJulianDay($julianYear, $julianMonth, $julianDay); echo "Julian Calendar date " . $julianYear . "-" . $julianMonth . "-" . $julianDay . " converted to Julian Day is: " . $julianDayNumber;</span>

This code performs the conversion from Julian Calendar to Julian Day. It first calculates the corresponding Julian Day and then outputs the result.

Conclusion

That’s the PHP implementation for converting Julian Calendar dates to Julian Day. Through this article, you can understand the basic concepts of these two date systems and the necessity of their conversion. Hopefully, this code example will help you better handle dates in your projects.