Analemma: The Shape of Time
Calvin Sridhara
Award: Top 100
Award: 1st Place Natural
School: leland high school
Teacher: kevin w. tibbs
Category: Natural
Photo #21010
Analemma: The Shape of Time
An analemma is a distinctive, asymmetrical figure-eight tracing the Sun's position across the sky, built from photographs taken at the same location and time for a year. Creating this complex composite demanded immense patience and perseverance. Using an iPhone camera, I captured 49 individual photos framed over a prominent archway at my high school. I rescheduled shooting days around cloudy afternoons, academic deadlines, and other commitments, and adjusted the shooting time for daylight saving transitions. Except for the background photo of the arch, all shots utilized a solar filter to prevent overexposure of the solar disk.
The resulting shape visually maps orbital mechanics dictated by Earth's axial tilt and elliptical orbit. The vertical axis represents changing solar declination. Because Earth's axis tilts at 23.44 degrees relative to its orbital plane, the Sun climbs higher in summer and sinks lower in winter, defining the upper and lower boundaries. The horizontal east-west spread represents the equation of time, measuring the discrepancy between uniform clock time and actual solar time. This variance stems from two compounding effects: Earth's axial tilt and its elliptical orbit, which causes our planet to travel fastest near perihelion in January and slowest near aphelion in July. Near the December solstice, these two effects reinforce each other, dramatically widening the east-west spread and ballooning the lower loop. Near the June solstice, they partially cancel, constraining the east-west spread and producing the smaller upper loop. Together, tilt and variable orbital speed assemble this beautiful solar mosaic.
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