Post subject: Final report from FRANCE
Location : Avenue d'Aquitaine 82130 Lafrançaise FRANCE
Located in the south-west of France countryside (3.000 inhabitants) . 17 km from Montauban (50.000 inhabitants), 70 km from Toulouse (650.000 inhabitants)
Grade and/or Subject Area
12 students from 10 to 15 years old of the astronomy club of the school are working during the lunch pause.
A summary of the activities you did including a description of your calculations.
The solar midday is calculated from an ephemeride.
Winter: drawing of a meridian line, using the corner of a window as the top of the gnomon
Spring: measurements with a one meter gnomon.
Summer solstice week : measurements with a gnomon with quadrant. Useful length of the gnomon: 882 mm, which is also the radius of the quadrant. (precision +/- 00°05')
Our blog is http://eratostwin.blogspot.com/
What were the highlights?
15th march:
Ides of March. Brutus was in a bad mood. The president of the students avoided his sword. At least she could realise these measurements.
Solar midday: 13:04 (TU+1)
Gnomon: 1,00m
Shadow: 1,05m
Angle of sun: 46°24'
Partner: Cancer tropic (Angle of sun: 25°41' Distance to Lafrançaise: 2298 km)
Circumference: 2298 x 360 / (( 46 + 24/60 ) - ( 25 + 41/60))
2298 x 360 / (46,400 – 25,683) = 39.932 km
Partner: Hoboken,NJ, USA (Day : 19th march, Latitude: 40,74 N, Angle of sun: 40,5° , Distance to Lafrançaise: 377 km)
The calculation with those measurements is not precise:
- 4 days between the measurements is too long.
- 377 km between the cities is not enough
Summer solstice: visioconference with Alexandria Library (Egypt) on june 21st to commemorate Eratosthenes measurement.
Angle of sun: 20°40' = 20,667°
Partner: Cancer tropic (Angle of sun: 00°00' Distance to Lafrançaise: 2298 km)
What would you do differently next time?
We spent too much time on the 2006-2007 Eratosthenes European project at http://www.mapmonde.org/eratos Next time we should be more active for the spring equinox on Noon Day Project
Conclusions - what did you learn from your participation?
Thanks to Ihor, to make possible this big meeting of students around the world , measuring the circumference of the Earth.