One of the highlights of the annual Festival of the Stone Spheres in the Osa canton is watching the alignment of the Sun with three magnificent and mysterious spheres in the early morning hours.

This is how journalist Andrea Solano Benavides of prominent news daily La Nacion described the mystifying event:

It was 5:45 am and the Sun embraced the Osa canton to welcome a new day. A fiery sphere of light rose over the horizon in perfect synchrony with three other spheres that lay on the grassy soil of the archeological site Finca 6 in Palmar Sur.

For the 40 spectators gathered to watch the sunrise, the occasion marked the beginning of the VII Festival of the Stone Spheres on April 14, 2012, but for our pre-Columbian ancestors it meant the end of a cycle and the beginning of another.

Such is the hypothesis presented by a group of investigators of the National Museum, led by archeologist Francisco Corrales, with regard to a possible relation between the alignment of the Sun with the spheres of Costa Rica, which were made sometime between 300 B.C. and 1500 A.D.

A lot of research and conjecture has gone into our mysterious spheres, and there is a consensus that points to uncertainty as to their true purpose. We know the Boruca people made them, and we think the Bribri used them, but what for?

The Bribri people are considered to be the earliest astronomers of the Americas, one of the reasons why Dr. Franklin Chang-Diaz of Ad Astra named his future Mars spacecraft project Bekuo -the Bribri term for shooting star.

In the past, it was believed that the triangular alignment of the stone spheres had something with magical beliefs centered on the solstice and the equinox , but such speculation was discarded.

The new research will be centered on agricultural calendars, meaning that ancient indigenous people in the region, may have planned their crops in accordance to the alignment, which signals the transition from the dry season to the rainy or green season.

The Zenithal Trajectory of the Sun

Don Jose Alberto Villalobos Morales is a professor and tutor who keeps a series of very entertaining and educational blogs on the subject that strikes fear in the hearts of many Tico high school and university students: algebraic physics. Professor Villalobos is of the opinion that the alignment of our stone spheres has more to do with aesthetics, or that maybe they served as a crude agricultural calendar, but he recently gave his expert opinion on the suggestion that the spheres are thus aligned to calculate the zenithal projection of the Sun.

To consider such hypothesis would be to think that our ancient astronomers wanted to know the point above an observer that is directly opposite the nadir on an imaginary sphere against which celestial bodies appear to be projected. This would mean that pre-Columbian ancestors in Costa Rica may have had a certain degree of knowledge about the spherical shapes of celestial bodies and their orbits.

The zenithal path of the Sun is equivalent to a solstice, something that those who aligned the stone spheres either knew about or suspected. The alignment will happen again in August, but the Sun will rise from the opposite direction. To follow this idea, the researchers will have to calculate the zenithal events of the Sun going back 1,500 years -taking into account any adjustments of the Earth axis.

To corroborate the speculation above, similar calculations and observations would have to be made on the rest of sites in Costa Rica where other stone spheres are aligned. Until then, their true purpose remains a mystery.