Syndication16 Dec 2007 - 08:33:23 pm
Using a scolarscope
A scolarscope is a box aimed at looking at the Sun without danger for the eyes.
The main parts are :
* a side with a white screen inside ;
* a tube through this side and containing a lens ;
* a bulging mirror in the box on the side in front of the tube.
In order to point at the sun :
1° out of the box : you make the shadow of the tube become as small as possible ;
2° then in the box : you make the light spot go on the mirror and be reflected on the screen, beside the tube.
In order to focus the picture, you have to :
1° check the length of the tube out of the box ;
2° turn the screw behind the mirror.
It is possible to estimate the apparent diameter (D) of the Sun :
1° you point at the Sun and draw the picture on the screen ;
2° you keep the picture in the drawing ;
3° you let the picture go out of the drawing and you measure the time (T) until the picture is entirely out of the drawing.
4° you calculate : D = 360° x cos(declination of the Sun) x T / 24 h
[“three hundred and sixty degrees multiplied by the cosine of the declination of the Sun multiplied by T divided by twenty four hours”]
For example, on the 9th of November 2007 :
* the declination of the Sun was -16,8° [minus sixteen point eight degrees]
* the time was : T = 2 minutes and 10 seconds = 130 s.
* the apparent diameter was : D = 345° x 130 s / 86 400 s = 0,52° (approximately)
Explanation :We can consider that :
* we are at the summit of a cone ;
* the Sun moves along the edge of the base of the cone ; it covers one turn in 24 h ;
* the angle at the summit of the cone is 180° - 2 x the declination of the Sun ;
* the angle at the centre of the pattern of the cone is 360° x cos(declination of the Sun)
The main parts are :
* a side with a white screen inside ;
* a tube through this side and containing a lens ;
* a bulging mirror in the box on the side in front of the tube.
In order to point at the sun :
1° out of the box : you make the shadow of the tube become as small as possible ;
2° then in the box : you make the light spot go on the mirror and be reflected on the screen, beside the tube.
In order to focus the picture, you have to :
1° check the length of the tube out of the box ;
2° turn the screw behind the mirror.
It is possible to estimate the apparent diameter (D) of the Sun :
1° you point at the Sun and draw the picture on the screen ;
2° you keep the picture in the drawing ;
3° you let the picture go out of the drawing and you measure the time (T) until the picture is entirely out of the drawing.
4° you calculate : D = 360° x cos(declination of the Sun) x T / 24 h
[“three hundred and sixty degrees multiplied by the cosine of the declination of the Sun multiplied by T divided by twenty four hours”]
For example, on the 9th of November 2007 :
* the declination of the Sun was -16,8° [minus sixteen point eight degrees]
* the time was : T = 2 minutes and 10 seconds = 130 s.
* the apparent diameter was : D = 345° x 130 s / 86 400 s = 0,52° (approximately)
Explanation :We can consider that :
* we are at the summit of a cone ;
* the Sun moves along the edge of the base of the cone ; it covers one turn in 24 h ;
* the angle at the summit of the cone is 180° - 2 x the declination of the Sun ;
* the angle at the centre of the pattern of the cone is 360° x cos(declination of the Sun)
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