Measuring the Sun's position above the horizon

Examples and Impressions

Some project day impressions of participants

Preparation impressions from Teheran (instead of project day pictures)

"Lieber Herr Prof. Backhaus,
leider hatten wir nicht so viel Glück wie die Messgruppe in Essen. Heute war das Wetter in Teheran so stark bewölkt und verhangen, dass es nur diffuses Licht gab und überhaupt kein Schatten zu sehen war. So können wir leider kein Messergebnis beisteuern, aber zwei Fotos. Damit die Enttäuschung nicht zu groß wird, sind wir kurz nach 12 Uhr nach abgebrochener Messung dann zum "Star Burger" gegangen und haben wenigstens zusammen was gegessen.
Die Vorbereitungen haben aber auch viel Spass gemacht und wir haben auch was gelernt. Gerne machen wir wieder mal mit bei den astronomischen Projekten.
Viele Grüße aus dem trüben Teheran
Fatima Chahin-Dörflinger" (Deutsche Botschaftsschule, Teheran, Iran)

Preparation: The Obelisk on the "Halde Hoheward" in Recklinghausen, Germany

The horizontal sundial on Halde Hoheward with its obelisk as a shadow caster is optimally appropriate to perform our experiments on a large scale. We visited it on March 21^rst and determined the actual value of the equation of time by observing exactly the time at which the shadow crossed the noon line (12:37:54 MEZ). With the exact longitude of the dial which is given on a display board (λ=7°10'11.5") we got eot=6m27s. (The exact value was 6m31s!)

The oblisk and its shadow just before noon just after noon


The oblisk and its shadow	just before noon	just after noon

In case of sunny weather on April 24^th, some of our partners will perform our measurements on a large scale.

The north-south-direction and our own geographical position

Registering the noon position of the shadow.
The line from north to south is already fixed. Noon results of April 2^nd


Registering the noon position of the shadow. The line from north to south is already fixed.	Noon results of April 2^nd

The first spring days at the beginning of April gave us the possibility of exercising and improving our procedures and of finding the exact northern direction. With our noon results of April 2^nd which can be read in the right picture above (and knowing the eot and the sun's declination of that day), we determined our geographical position. Our result: φ=51.6°, λ=6.8°. (Our GPS states as the correct position: φ=51°27.839'=51.434°, λ=7°0.240'=7.00°.)

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Udo Backhaus

last change: 29.04.2009