On 21/09/2012 02:32, RichD wrote:

When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

A reasonable list of who, what, when and where is online at:

http://articles.adsabs.harvard.edu/c...;filetype=.pdf

(I think this link should be public)

It reckons Chuo Li, China 1100BC 30

This list misses out Oenepedes, Greece 450BC 24

http://www-groups.dcs.st-and.ac.uk/~...Oenopides.html

--
Regards,
Martin Brown