The definition of a Sidereal Day is as follows: Measured relative to an infinitely distant, fixed point, the time it takes for Earth to complete a 360-degree rotation is ONE SIDEREAL DAY. The Sidereal Day is relatively stable and lasts 23 hours, 56 minutes, and 4.09 seconds. However, it is an interesting exercise in mathematics to compute the lengths of Sidereal Days with less distant objects as reference points. Using the same definition, the Object-Relative Sidereal Days here are calculated by the interval of time between two successive points in time in which the center of this object passes Earth's Prime Meridian. Suppose that at a time t_0, Mars is directly due north or due south of Greenwich. At another, later time, t_1 this condition is fulfilled again. Further, if there is no t_0 < t < t_1 such that the condition is fulfilled, t_1 - t_0 is a Mars-relative Sidereal Day. Due to the nature of orbits and axial tilt, these object-relative Sidereal Days fluctuate. Tables are provided for the following bodies: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune [HOW TO READ THIS TABLE] # : SID. DAY INDEX IN YEAR MD_0 : START MERIDIAN TIME MD_1 : END MERIDIAN TIME DURATION : SID. DAY DURATION DEC_1 : START DECLINATION DEC_0 : END DECLINATION