Finding your latitude

The task was simple, we thought. Find your geographical latitude by means of one of a series of methods - that was the contents of the Final Event. Exact 50 groups took part, and it is evident from the reports, they filed, that while the task was simple, executing it was less trivial, especially for those who went to great lengths to determine the latitude by astronomical means.

A report which the author of these lines enjoyed very much came from Avventurosi in Bologna, Italy. It said: We are Avventurosi in Bologna, Italy. We used the 2nd method and we have done the measurements this Tuesday at the Elementary School Grosso in Bologna with a 3rd class. The gnomon was a child 132.5 cm tall. The shadow was 272 cm. We calculated arctg (132.5/272) and we transformed the results into 25.7722 deg or in sexagesimal 25^o 58' 20". We calculated our geographical latitude and the result is 44^o 33' 40". We had some problems: Sometimes the gnomon is moving! Thank you and a good final event!.

Unfortunately, the weather did not behave very well, but thanks to the determination and stamina of many participants, they nevertheless managed to get good results. This is particularly evident from the last report, which we received from Larissa, Greece. In a final summary statement, it said We're late because now the sky is clear. Well done, Larissa and all the other groups!

Not everyone was lucky, and many groups had to resort to method 4 (looking at a map). Not surprisingly, they got very precise results. However it was clear that while the results from method 4 look very good, it is much more fun to go out and do real astronomical measurements yourself. So, to those who had to accept the hard facts of the European November weather: How about giving it another try at a later date? Remember, Astronomy On-Line may close tonight, but the sky will stay with us...!

The table below summarizes the results, arranged by measured geographical latitude. We start at the top, in Northern Norway, and pass towards South, all the way to Greece and the USA and on to Chile, spanning nearly 110 degrees in latitude. Did you know that Palermo (Italy) and Ekali (Greece) are almost on the same latitude?

The last column indicates the method used to find the latitude: 1) by observing the Polar Star; 2) by observing the Sun; 3) by serching on the WWW; and 4) by measuring on a map. There were 12 measurements by method 1, 17 by method 2, 3 by method 3 and 12 by method 4 (that is where the weather did not collaborate). 6 groups did not indicated which method they used.

A final question: would the northernmost group in Tromsoe (Norway) have been able to determine their latitude by means of the second method, that is by measuring the altitude of the Sun? Think before you answer!

And now the Surprise!

Each of the groups that participated will receive an original, large colour print from ESO's collection, showing one of the most spectacular astronomical objects in the southern sky. We will send it off to you as soon as possible, but it may take a few days to prepare the envelopes. Think of it as as small expression of our gratitude for your active participation in this very special project.

Claus Madsen
ESO Education and Public Relations Dept.