As the year comes to a close, it’s time to take a look back at some of the most memorable events and images of 2017. Among the events covered in this essay (the first of a three-part photo summary of the year): the inauguration of President Donald Trump; the Women’s March on Washington; the retaking of Mosul, Iraq, from ISIS; observations from Saturn; massive opposition rallies in Venezuela; and much more. See also, the Top 25 News Photos of 2017, and, coming over the next two days, the Year in Photos, Part 2, and Part 3. The series will comprise 120 images in all. Warning: Some of the photos may contain graphic or objectionable content.