Nalini Chandra & John Percy, University of Toronto
Purpose: To introduce student to the idea that the sky appears different to observers at different latitudes.
1. Compare pictures of the sky at the same times but at different latitudes, and record:
(All of these should be specified by the planetarium software)
2. Have students make a chart to list similarities and differences between the observations.
3. Mark the positions from which these pictures would have been taken on the celestial globe and give students the opportunity to account for differences or similarities observed.
Note: A trip to a real planetarium could be useful in helping students to compare their own observations of objects in the sky to those represented in the celestial globe or simulations.
Observing the Changing Position of the Sun To Establish Cardinal Directions
There is evidence to suggest that early people made careful observations of the rising and setting of the Sun and were able to recognize that the Sun didn't just rise and set anywhere. Observations of the Sun's apparent movement across the sky and its pattern of rising and setting in the east and west horizon helped to establish the cardinal directions.
For the Hopi of Arizona, the cardinal directions were not like our north/south/east/west, but related the directions to the points on the skyline where the Sun rises and sets at the solstices. These positions are roughly north-east, south-east, north-west, and south-west. The beginning of the Hopi winter was determined by the Sun Chief and the Soyal Chief (soyal means the solstice ceremony). Anthropological records of the Hopi Horizon calendar show the Sun priest's observations for the purpose of timing the midwinter ceremonies. In these diagrams, changing position of the Sun is drawn with respect to its position between two peaks in the San Francisco mountains. For instance, the Sun setting in the notch between two particular San Francisco mountain peaks, near Flagstaff Arizona, was the signal to begin, in four days, the nine day celebration of the winter solstice.
Purpose: To give students the opportunity to observe the changing position of the Sun and understand how observations of these patterns helped to establish cardinal directions.
Note: If observations occur in the early fall expect earlier Sunsets, and later Sunrises, and southward shifts. If observing past December, expect later Sunsets and earlier Sunrises and northward shifts. "Solstice" means "standing still" and students should expect very little change in the weeks prior to and after the solstices (Dec. 21 and June 21). Around Equinoxes (Sept. 22 and March 22) Sunset time and position changes are dramatic.
Observing the Changing Position of the Sun To Establish a Seasonal Calendar
Among those groups of people on Earth, whose means of survival is solely dependent on hunting and fishing are the Inuit. For them, the Sun does not rise for some period of time. The cycle of the Sun and the Moon are of great importance in determining the festivities and subsistence of this culture. At the far northern latitude of Igloolik which is 69 í 22'N, the Sun falls below the horizon on the 29th of November and is not seen again until the 14th of January. It is constantly above the horizon for the sixty-six days between the 19th of May and the 24th of July. It was important for the Igloolik, which is one of the Inuit cultures, to track the altitude of the Sun to determine how long it was before the dark days of winter were upon them. For instance, even though the Sun would be above the horizon every day for 24 hours, it's highest position in the sky would become progressively lower and lower as winter approached. The time of the Sun's return after the dark days of winter signaled a renewal of food and festivities for the Igloolik. The Igloolik had very interesting means of observing the Sun's return and measuring the Sun's altitude and they identified three different stages, each signifying something of importance to the Igloolik culture. The first stage of the Sun's return was observed when a harpoon shaft held horizontally at arms length at noon would fit between the horizon and the lower rim of the Sun's disk. This indicated that the Sun was barely back on its return. The second stage was observed when you extended your arm and the thumb of your mitted hand would fill the gap between the Sun and the horizon. This stage signaled the start of seal hunting. The final stage of the Sun's return was marked by the observation that the Sun had reached its highest altitude when the full width of your mitted hand could fill the gap between the Sun and the horizon. This observation marked the end of the winter and the time when the chances for catching marine animals would be better (MacDonald, 1998)
This description of how a simple means for measuring the Sun's altitude was used by the Igloolik to determine their seasonal changes and hunting periods, could help to illustrate to students that the they do not necessarily need complex or high-tech instruments to make simple informative observations of the sky or to track the changing position of celestial objects. The method illustrated below has been known to be quite "handy" for estimating the angle of sky object above the horizon.
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