pinhole solar viewer

[paulsutton]

Hi all

I would like to try and build a solar observer as detailed here

https://www.space.com/15614-sun-observing-safety-tips-infographic.html

Right now I have 2 pieces of card one is square with a pin hole in the center  the other is just a piece of scrap a4 card.l  The projector does work.

I have got a basic pinhole projector working,  is there a way to link distance from hole to the size of the  projected image, ?  Or the optimum size of hole and distance to where I am projecting to?

Thank in advance for any help

II can probably use a system lke this in a school or at the South Devon Tech Jam if we decide to actually do more than simply computers and programming.

Regards

Paul

 

 

[swansont]

2 hours ago, paulsutton said:

Hi all

I would like to try and build a solar observer as detailed here

https://www.space.com/15614-sun-observing-safety-tips-infographic.html

Right now I have 2 pieces of card one is square with a pin hole in the center  the other is just a piece of scrap a4 card.l  The projector does work.

I have got a basic pinhole projector working,  is there a way to link distance from hole to the size of the  projected image, ?  Or the optimum size of hole and distance to where I am projecting to?

Thank in advance for any help

II can probably use a system lke this in a school or at the South Devon Tech Jam if we decide to actually do more than simply computers and programming.

Regards

Paul

 

 

The image size increases linearly as you make the camera longer. It’s also going to depend on the object’s angular size.

[paulsutton]

Just now, swansont said:

The image size increases linearly as you make the camera longer.

Cool thanks, 

 

Paul

[paulsutton]

I have an experiment to work out the angular size of the moon. 

Clearly with the moon I can take a coin and measure the diameter, then measure the distance from me at which the moon is covered,  by looking at the moon.   Now given doing this with the sun is going to be a bad idea,   
 

As the normal equation gives size in radians as per

angular size  = (actual x distance)

The OU course I did modifies the equation for this with

Angular size = 57 x (actual size / distance) which I think converts radians to degrees.

I am sure it should be possible to modify to work out the angular size of the sun.    According to my book the sun is 400 x bigger than the moon so if I work out the size of the moon then x 400 I should get the  angular size of the sun which is what the projector will be looking at.

Which sort of makes sense.

Does this sound right.? 

Thanks

Paul.

 

 

[swansont]

The angular size is about the same, which is why we get solar eclipses. The sun is ~400x bigger but also ~400x further away.