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If you compare our results (in staff room) of December (sunspot 1131) and January (sunspot 1147) you can observe the different rotation of the Sun depending on the different latitude .

The more latitude the less speed and more days .

Fontenay-le-Comte

(direct translation of pupils' calculations)

Displacement of sunspot n°1166

From march 5th at 8h45 to march 11th at 8h05, there are 6 days – 40 minutes.

6 days = 6 × 24 × 60 = 8640 minutes

6 days – 40 minutes = 8640 – 40 = 8600 minutes.

On the grid, there are 18 squares to make half of the Sun, i.e. 180°. So, 1 square makes 10°. When you watch the grid, you see that the spot takes 8600 minutes to make 80°. Our spanish partners tought us that we must add one degree per day because Earth rotates around Sun.

« But the mistake is that we put all the sunspots in the same grid and from our point of view the grid is changing (due to the orbital Earth's motion) and everyday we can see 1 degree more of the back side of the Sun so everyday we have in front of us a different meridian of the Sun . »

 

So the spot takes 8600 minutes to make 86°. It would then take 36000 minutes pour faire 360° (a complete revolution).

36000 ÷ 60 ÷ 24 = 25 days.

Displacement of sunspot n°1164

From march 3rd at 7h50 to march 7th at 8h40, there are 4 days + 50 minutes.

4 days = 4 × 24 × 60 = 5760 minutes

5760 + 50 = 5810 minutes

On the grid, the sunpot takes 5810 minutes to make about 55°. We add 4° for 4 days. So the spot takes 5810 minutes to make 59°. It would then take

5810 × 360 ÷ 59 = 35450 minutes to make a complete revolution.

35450 ÷ 60 ÷ 24 = 24,6 days

Our spanish and greek partners noticed that the further we are from equator the longer the time to make a revolution. This is not true for our calculation. (sunspot n°1164 is higher than n°1166). We will try again on other spots.

 

 

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