Ron Torell, former University of Nevada Extension livestock specialist now retired, wrote a few years back that most cows pay for themselves by age six. âThus, the longer a cow stays in the herd, the more profitable she becomes.
Naturally, these hours, minutes, and seconds are shorter than the solar hours, minutes, and seconds you are familiar with. One solar day is 24 solar hours long, and one sidereal day is 24 sidereal hours long, but one sidereal day is 23 solar hours and 56 solar minutes long. This exercise was based on a help section of CyberSky. A shareware version of CyberSky is available from http://www.cybersky.com .
Relative to the stars, the sidereal period is the time it takes for a planet to complete one orbit. The orbit of a planet around the Sun measured with respect to the âfixed starsâ is used to determine the sidereal period. The sidereal period of the Earth is 365.25636 mean solar days, which is slightly longer than the tropical year (measured between successive vernal equinoxes) of 365.24219. In most calendar systems, the length of the year is taken to be 365 days, which is close to the Earthâs sidereal period. Leap years are added to reduce the amount of calendar drift between the observed dates of events (e.g. solstices and equinoxes) and their expected calendar dates. Planetary data: Sidereal Periods