parts of Mesoamerica this was considered a significant day as it would herald the arrival of rains, and so play a part in the cycle of agriculture. This knowledge is still considered important amongst Mayan Indians living in Central America today. The ethnographic records suggested to archaeoastronomers that this day may have been important to the ancient Mayans. There are also shafts known as 'zenith tubes' which illuminate subterranean rooms when the Sun passes overhead found at places like Monte Albán and Xochicalco. It is only through the ethnography that we can speculate that the timing of the illumination was considered important in Mayan society. Alignments to the sunrise and sunset on the day of the zenith passage have been claimed to exist at several sites. However, it has been shown that, since there are very few orientations that can be related to these phenomena, they likely have different explanations. Ethnographies also caution against over-interpretation of sites. At a site in Chaco Canyon can be found a pictograph with a star, crescent and hand. It has been argued by some astronomers that this is a record of the 1054 Supernova. However recent reexaminations of related 'supernova petroglyphs' raises questions about such sites in general. Cotte and Ruggles used the Supernova petroglyph as an example of a completely refuted site and anthropological evidence suggests other interpretations. The Zuni people, who claim a strong ancestral affiliation with Chaco, marked their sun-watching station with a crescent, star, hand and sundisc, similar to those found at the Chaco site. Ethnoastronomy is also an important field outside of the Americas. For example, anthropological work with Aboriginal Australians is producing much information about their Indigenous astronomies and about their interaction with the modern world. Recreating the ancient sky Once the researcher has data to test, it is often necessary to attempt to recreate ancient sky conditions to place the data in its historical environment. Declination To calculate what astronomical features a structure faced a coordinate system is needed. The stars provide such a system. If you were to go outside on a clear night you would observe the stars spinning around the celestial pole. This point is +90° if you are watching the North Celestial Pole or −90° if you are observing the Southern Celestial Pole. The concentric circles the stars trace out are lines of celestial latitude, known as declination. The arc connecting the points