SDAC

[Joseph Hedhli Buell]

I found a site sort of similar to APOD, called SDAC. It is also under a nasa.gov URL. It shows images of the sun every day from the Goddard Space Flight Center, which is why I sometimes refer to it as SPOD (Sun Picture of the Day). From what I can tell, as not even an amateur astronomer, it's ten different images of our Sun, with different filters, to better show flares, sunspots, coronal holes, or other things. I also noticed, under each image, is some text. I assume this indicates the type of filter, but am still confused as to why some of them say 'Fe' or 'He'. I assume these have something to do with the periodic elements, iron and helium, but don't know what they have to do with the filters. I'd greatly appreciate an experienced astronomer to tell me what this is about.

https://umbra.nascom.nasa.gov/images/latest.html

It even has an index: https://umbra.nascom.nasa.gov/sdac/

[Chris Peterson]

I found a site sort of similar to APOD, called SDAC. It is also under a nasa.gov URL. It shows images of the sun every day from the Goddard Space Flight Center, which is why I sometimes refer to it as SPOD (Sun Picture of the Day). From what I can tell, as not even an amateur astronomer, it's ten different images of our Sun, with different filters, to better show flares, sunspots, coronal holes, or other things. I also noticed, under each image, is some text. I assume this indicates the type of filter, but am still confused as to why some of them say 'Fe' or 'He'. I assume these have something to do with the periodic elements, iron and helium, but don't know what they have to do with the filters. I'd greatly appreciate an experienced astronomer to tell me what this is about.

https://umbra.nascom.nasa.gov/images/latest.html

It even has an index: https://umbra.nascom.nasa.gov/sdac/

Different elements, when ionized, emit very specific, narrow wavelengths of light. By carefully choosing the right filters, we can image an object only by the light of those elements. Essentially, we are seeing only the contribution from helium, or iron, or hydrogen, or any other element that is scientifically interesting.