HôChiMinhCity Vietnam
June 2010
HôChiMinhCity | Vietnam | HAAC | 10°46’N | 106°39’E |
Date | Gnomon | Shadow | Angle |
---|---|---|---|
june 21nd | 130.5 cm | 29.3 cm | 12°39’ = 12.654° N |
Résults on HAAC forum
Founded by some people who loved astronomy in Ho Chi Minh city 19/5/2007. At now, the club is supported by Vietnam Astronomy and Space Association and Ho Chi Minh City Institute of Physics.
At now the club is the biggest amateur astronomy club in Vietnam with more than 100 members in Ho Chi Minh city. Besides, nearly hundreds of members participate and discuss online through our website www.thienvanhoc.org. More than 60 percent of members are students and pupils.
HAAC: always holds a lot of events such as astronomy observations, basic knowledge, hand-made telescopes. Coordinate with some schools to widespread astronomy in Vietnam.
++++The result in HCM City (20 June)
The pole length =130cm, shadow length = 29.1cm
Local noon at 11:53AM
Angle n = arctan (29.1/130)= 12.61754 degree
Distance from hcm to Tropic of Cancer (D) is 1409.17 km (10.769N)
Earth’s circumference =360* D/n= 40206 km
++++The result in HCM City (21 June)
The pole length =130.5cm, shadow length = 29.3cm
Local noon at 11:55AM
Angle n = arctan (29.3/130.5)= 12.65426 degree
Distance from hcm to Tropic of Cancer (D) is 1409.17 km (10.769N)
Earth’s circumference =360* D/n= 40089.35 km
++++Result in another province in VN
Hà Nội: 21.033 N, Local noon is 11:58AM, D= 268.94 km, n= arctan (5.7/100) = 3.26°
Earth’s circumference =360* D/n=?
Đà Nẵng: 16.07N, Local noon at 11:57AM, D=822.38 km, n=arctan(7.5/58)=7.37 degree\
Earth’s circumference =360* D/n=40181.15 km
Bảo Lộc: 11.5N, D= 1350.27 km,n= arctan(17.5/83.4)= 11.85 degree, distance to tropic of cancer is 1328.04 km,
Earth’s Circumference = 40345 km
Thanh Hóa: 19.81 N, D= 402.52 km, n= arctan (6.2/99)= 3.583619 degree
Earth’s circumference =360* D/n= 40436 km
Đồng Tháp: 10.35N, D=1451.03 km, n=arctan(27.1/116.9)=13.05187676 degree
Earth’s circumference =360* D/n=40022.658 km
Playku: 13.99N, D= 1031.52 km,n= arctan(17.5/83.4)= 11.85 degree
Earth’s circumference =360* D/n=31 430 km
Bảo Lâm:11.7N, D= 1313.04 km,n=arctan(17.5/83.6)=11.823 degree
Earth’s circumference =360* D/n=39980.92 km
++++Result in Method 2
Reason: Thanh Hoa and Dong Thap have the same longitude 105.7 East
n1 in Thanh Hoa at local noon is 3.583619 degree
n2 in Dong Thap at local noon is 13.05187676 degree
Distance (D) between two locations above is 1048.51 km
n= n2-n1 = 9.46825776 degree
Earth’s circumference =360* D/n=39886.215 km
Local noon at one place: the time which have shortest shadow length or the time between sunrise and sunset
++++Achievement
Help participants know more about Earth’s sphere, Tropic of Cancer, sunlight’s shadow on earth, principles for computing and explain some equations.
The way Eratosthenes uses to determine the Earth’s Circumference thousands years ago.
Participants can compute Earth’s Circumference themselves by measured the angle of elavation of Sun in Summer Solstice.
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