# Easy Question, Sunspots Astronomy Umbra and Penumbral sunspot areas

Didnt know if this is the write palce to put this, but im stuck on this assingment and i think it must have an easy solution so if someone could point me in the right direction then it would be much appreciated.

## Homework Statement

Using an appropriate software package, quantify the umbra and penumbral areas, normalised to the total image area, for the sunspot image provided (Sunspot image can be found on eBridge). Quantify and comment on the uncertainty in your measurements and discuss the significance of determining umbra and penumbral sunspot areas.

N/A

## The Attempt at a Solution

This is the third and final question on the assingment, i have done the other two but arnt quite sure where to start with this one.. the only idea i thought of would be to use something like photoshop and use circles to border the Umbra and Penumbra areas with minimal, max and average circles which would provide me with an area and then the min and max would provide me with an area, however this seems to be like it would provide extremly large errors
The only other option i thought of would be to count the pixels individuall of the Umbra and Penumbra, but this isnt something i think i could bring myself to do as im sure you could understand.

Any help is much appreciated.

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## Answers and Replies

berkeman
Mentor
Didnt know if this is the write palce to put this, but im stuck on this assingment and i think it must have an easy solution so if someone could point me in the right direction then it would be much appreciated.

## Homework Statement

Using an appropriate software package, quantify the umbra and penumbral areas, normalised to the total image area, for the sunspot image provided (Sunspot image can be found on eBridge). Quantify and comment on the uncertainty in your measurements and discuss the significance of determining umbra and penumbral sunspot areas.

N/A

## The Attempt at a Solution

This is the third and final question on the assingment, i have done the other two but arnt quite sure where to start with this one.. the only idea i thought of would be to use something like photoshop and use circles to border the Umbra and Penumbra areas with minimal, max and average circles which would provide me with an area and then the min and max would provide me with an area, however this seems to be like it would provide extremly large errors
The only other option i thought of would be to count the pixels individuall of the Umbra and Penumbra, but this isnt something i think i could bring myself to do as im sure you could understand.

Any help is much appreciated.

Interesting. Do you have any image processing software packages that you could consider for use on this? Not so much Photoshop, but more like image enhancement and processing?

If you had a graphics tablet, you could trace the circumferences of the two parts, and then you'd need some way to calculate the area enclosed by the traced lines. Do you know of any software packages that allow you to do that?

Ive jsut spoken to a friend that used photoshop and the lasso tool to outline the areas then using one of the options it will give a pixel count. i can understand how this will give me the area, and thus the ratio, but not how i could quantify any errors in this calculation..

Thanks for the reply

berkeman
Mentor
Cool. I didn't know Photoshop had that feature. Good to know.

Can anyone explain the significance of the umbra and penumbra areas?

Thats a good link but doesnt explain the significance of the areas of the umbra and penumbra areas shamefully....