๐ Julian Day Converter
Converts between a Gregorian calendar date and the Julian Day Number (JDN) โ a continuous day count starting from noon UTC on January 1, 4713 BCE, widely used in astronomy. The Modified Julian Day (MJD) is shown as well.
How to use
- Enter a date to automatically calculate its Julian Day Number (JDN).
- Or enter a JDN to automatically calculate the corresponding calendar date.
- The Modified Julian Day (MJD = JD - 2400000.5) is shown alongside the result.
FAQ
What is the Julian Day Number (JDN)?
It's a continuous integer day count starting from noon UTC on January 1, 4713 BCE. It's used in astronomy and calendrical calculations as a common reference point for comparing dates across different calendar systems.
What is the Modified Julian Day (MJD)?
It's the JDN minus 2400000.5 โ a more compact-digit date representation commonly used in modern fields like satellite orbit calculations.
Does this use the Julian or Gregorian calendar?
This tool calculates based on the Gregorian calendar currently in use. Dates before October 15, 1582 are treated using the "proleptic Gregorian calendar" โ the Gregorian rules extended backward in time.