Yahoo image popular search today

It is interesting how some of the most popular pieces of content on this website are photos. Today the visits from Yahoo image search are way more than I would normally receive. The traffic to this sun rising photo are huge.

It is interesting that referrals from Pinterest are usually the reason photos are popular. At times however, the image search for Google/Yahoo are very popular as well. Search engines are capricious. Why is today my photo of the sun popular and not yesterday?