Encore - Analemma of Kolozsvár City

December 21, 2019

Analemma_kolozsvar_2012_2013 (2)

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

: Pal Varadi Nagy
Summary Authors: Pal Varadi Nagy; Jim Foster

March 2014 Viewer's Choice The photo composition above is an analemma. It traces the yearly movement of the Sun above Cluj-Napoca, Romania, from the same location in the city and at the same time of day. Earth's 23.5-degree axial tilt contributes to both the length and the width of the figure eight, while the extra lateral deviation is attributable to the eccentricity of Earth's orbit. The winter solstice is at lower right; the summer solstice is at upper left. If the Earth had a circular orbit the northern and southern lobes of the figure eight would be the same size. Note that white dots show the Sun's position on 26 different days of the year --  about every two weeks, depending on weather conditions. The date of the city view is August 3, 2013.

Photo Details: Time of day (7:30 UTC) chosen to ensure a clear vista. Fuji HS20EXR at 24 mm; handheld; Lens calibration and picture assembly in software developed by me in PHP/GD with a DOM/javascript interface. A tripod was used.