Noon Shadows and Ring Eclipses: An Astronomy Club Year

The Shadow Post

1The astronomy club at Ridgeview Middle School, at 40° north latitude, spent a whole school year on one simple tool: a straight post exactly 1 m tall, set upright in flat ground beside the school's front walk. On about the 21st of each month, club members measured the post's shadow at local noon, when the Sun is highest, and used a sky app to record how high the Sun was in degrees above the horizon. Early in the morning, they also noted the direction where the Sun came up. Club president Ayaan Whitfield made Table 1 from their notes.

2The club's advisor, Mr. Leopold Ferrante, set up a model in the gym. A lamp in the center stood for the Sun. A student carried a globe in a big circle around it to stand for one year. The globe's axis was tilted 23.5° and pointed toward the same wall the whole time, the way Earth's axis keeps pointing toward the same place in space. The club stuck a short toothpick upright on the globe at 40° N and watched its tiny shadow at four spots around the lamp.