Historical & Astronomical
Modified Julian Date Calculator
Convert between standard UTC calendar dates, astronomical Julian Date (JD), and Modified Julian Date (MJD). Essential for astronomy and satellite geodesy.
Date & Age Calculator
Total Calendar Days364 Days
Working Business Days260 Work Days
Frequently Asked Questions
What is the formula for Modified Julian Date?
MJD = JD - 2,400,000.5. The 0.5 offset shifts the Julian day beginning from 12:00 UTC noon to 00:00 UTC midnight.
What was the MJD epoch zero date?
MJD 0 corresponds to midnight on November 17, 1858.
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