First, download it ;)
Then extract it to somewhere (zip file), depend on your OS (Win or Mac), go inside. Find a file with name sun.widget and open it (if Yahoo Widget installed correctly), and it will run.
However, depend on your setting, "Sun" and "Moon" should visible or you will not see it (it hide somewhere =)). So, go to setting (go with sidebar if you don't see where widget is), change the Longitude and Latitude, I… suggest 90, 45 then it should display at center of your screen. Increase a size if you don't feel comfortable.
PS: The image is not nice enough, hope author can make some other images or allow select another image (I want really woman in the moon and man in the sun :D)
I tried deleting it, and redownloading it. The widget wont work. Its a shame cause it would be a nice gadget to have on my desktop. Disappointed, so i say, dont bother to download.
This is a nice widget. It does work. However, you have to into the widget preferences, then exit for the widget to update. If you could make it auto-update, perhaps every hour, or half-hour, it would make this perfect :D Even better, create a drop-down list of how often the user wants it to update.
I would also suggest adding a browse function that allows the user to select their own sun/moon images. It's not really needed, but it would be a definite plus ;)