Modified Julian date
The Modified Julian Date (international abbreviation MJD ) is a time scale for chronology and geosciences introduced by the Smithsonian Institution in the International Geophysical Year (1957/58) .
The zero point of the timescale is on November 17, 1858. The Julian date is modified by decreasing the YD by 2,400,000.5 days.
How to get:
- smaller numbers and
- a day that starts at midnight Greenwich (0 a.m. UT) instead of 12 p.m. UT (civil hour counting instead of astronomical)
The MJD is mainly used in geodesy , geophysics , metrology and space travel , as well as astronomical chronology and calendars , but could only partially establish itself in astronomy . The transmission of the date of the program information (EPG) on digital television also uses the MJD.
The current MJD is for example: 59088.8165856 (= 08/27/2020 19: 35.53 UT)
A simple conversion (MJD-40587) * 86400 gives the Unix time (number of seconds since January 1st, 1970 UTC) approximated to the leap seconds .