Precession - could it be calculated 100% in ancient times?

[chriswhite]

I see that it was discovered pretty early

 

Though there is still-controversial evidence that Aristarchus of Samos possessed distinct values for the sidereal and tropical years as early as ca. 280 BC, the discovery of precession is usually attributed to Hipparchus of Rhodes or Nicaea, a Greek astronomer who was active in the 2nd century BC.

 

answers.com/topic/precession-1 (sorry, cant post links yet)

 

I was wondering however, if the precise 26,000 approx. cycle could be calculated using early astronomy or mathematics.

 

I have heard fractals somehow could have helped in this.

could be way off.

 

anyone have any insight?

[Pyrotex]

Hi there!

I've been interested in astronomy for about 50 years, and so I think I know how they did that.

Basically, they just measured it. The stars shift in precession by one degree in (26,000 / 360) years. That's only 72 years. The ancients could easily measure a star's position to ten times that accuracy. I mean, the Moon is half a degree wide, so we're talking an accuracy of only 1/5 of the Moon's diameter.

And their cultures remained stable for centuries, in some cases. And they kept records. So, it is entirely possible for an astronomer to plot the positions of some stars at midnight, at the equinox, and his grandson to plot the same stars 72 years later and realize that the stars have all shifted one degree in that time. Multiply by 360, and you get the precession cycle of 26,000 years.

Almost certainly, this is how they did it. Because that's all it takes.

[chriswhite]

Hi there!

I've been interested in astronomy for about 50 years, and so I think I know how they did that.

Basically, they just measured it. The stars shift in precession by one degree in (26,000 / 360) years. That's only 72 years. The ancients could easily measure a star's position to ten times that accuracy. I mean, the Moon is half a degree wide, so we're talking an accuracy of only 1/5 of the Moon's diameter.

And their cultures remained stable for centuries, in some cases. And they kept records. So, it is entirely possible for an astronomer to plot the positions of some stars at midnight, at the equinox, and his grandson to plot the same stars 72 years later and realize that the stars have all shifted one degree in that time. Multiply by 360, and you get the precession cycle of 26,000 years.

Almost certainly, this is how they did it. Because that's all it takes.[,

 

perfect timing, i was writing an article about this and I was just now dealing with this issue, you did a fabulous job of breaking this down in a coherent way, thank you.

 

I was using several lines of thought, but overlooked the easiest explanation :phones: