533 Serbia April 2020

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International Day of Light: The Parallel Earth and the Seasons 2020

Parallel Earth to Watch the Season ACTIVITIES TO CARRY OUT AND SEND Perform the Parallel Earth Experience after reading the description of the proposal and submit Table 1 completed with the acquired data and one or more attached images of the experience. If you wish, also send a photograph of a solar clock made by your students.

Table 1. Parallel Earth Data Biljana Stojičić

Teacher's name email

biljanastojicic963@gmail.com The Zemun Gymnasium (Zemunska gimnazija), students Rade Dragaš and Stefan Lazarević

School City, Country



Latitude, Longitude



Day and hour

28th April 2020, 12:20h and 13:25h

Note: it is very important that the photographs correspond to the place, day and time mentioned in Table 1 Optional: to complete the experience, those professors and students who wish may send photographs of a solar clock made by them. Project launch: March 20, 2020 (equinox) The activity will be open until: September 23, 2020 (equinox) The results are framed within the initiative of the International Day of Light

Visualization of the passage of Sun through the local meridian plane using Parallel Globe with sticks along the local meridian and equator

28th April 2020 at solar noon (12:20h)

At local noon, shadows of sticks along the meridian lie along the Meridian. The length of the shadow is zero at the latitude of 14 0 , in agreement with the value of the declination of the Sun at that day. The value of the declination is given for example at https://people.physics.tamu.edu/krisciunas/ra_dec_sun_2018.html Shadows of the sticks lying along the Equator fall on the Southern hemisphere, because in April Sun is above the Equator. The stick with the shortest shadow along the Equator lies at the intersection of the local Meridian and the Equator.

Photo of the Parallel globe at 13:25h on 28 April 2020. 65 minutes after the Sun passed through the Meridian plane, shadows of sticks lying along the Zemun meridian are directed towards the East because Sun moved to the West.

Determination of the direction of the local medirian on the terrace of the Grammar school in Zemun, Serbia

Local meridian is along the direction of the shadow of the gnomon at solar noon. The time of the solar noon was taken from the site https://www.esrl.noaa.gov/gmd/grad/solcalc/

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