Measuring How Many Days Are in a Year - Comments

In summary, this post discusses various ways to measure a year, including human observation of the moon, Earth's rotation rate, atomic clocks, and ways to measure a year using celestial bodies. Various issues with these methods are also discussed, such as the rotation rate of Earth and the need for fundamental constants with dimensions.
  • #71
Think I’ve figured out how Wikipedia got 365.256363004 SI days for the Sidereal year?
Earths semi-major axis a = 1.4959974465490E+11 Metres.
Gravitational constant G = 6.67408E-11 Newton Metres squared / kilogram square
Suns mass M1 = 1.98855E+30kg
Earths mass M2 = 5.97237E+24kg
T = 2*PI()*SQRT(a^3/G*(M1+M2))
Orbital period T = 31558149.76354540 SI seconds
 
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