Why is the ranking changing for days in the past? Aren the Explore rankings frozen each day?
No. The rankings in Explore for all dates change all the time even for dates in the past. Photos are uploaded to Flickr at a rate of around 5,000/minute and are constantly being viewed, faved, and commented by millions of members. Interestingness rankings are recalculated for all photos many times per day. Photos uploaded a day, a week, even a year ago, are still receiving activity in the form of views, comments, favorites, etc. And all of that activity affects each photo’s Interestingness ranking, even for photos that were uploaded years ago. Explore is very dynamic. When you browse through Explore on any date, you are viewing what the Interestingness algorithm has selected as the highest ranked photos at that moment.
