Equinocios-Hora solar

http://www.cientec.or.cr/astronomia.html

http://scienceworld.wolfram.com/astronomy/VernalEquinox.html

http://www.juanjomorales.com/2010/10/tema-1-2.html

http://www.iesmariazambrano.org/Departamentos/flash-educativos/tierra_mov.swf

Hora solar
http://rmcfisica4.blogspot.com/2010/04/hora-solar.html#comment-form