The week of December 17-23 takes us from the end of Day 9 through Day 16. This week we will highlight Mare Humorum, the Hippalus rilles, the craters Gassendi, Gassendi A (all viewable on Tuesday evening), and Comet 46/P Wirtanen.
A Sky Viewer’s Delight: Rilles, Craters and Comets
![A Sky Viewer’s Delight: Rilles, Craters and Comets A Sky Viewer’s Delight: Rilles, Craters and Comets](http://andrewplanck.com/wp-content/uploads/2018/12/Mare-Humorum-750x350.jpg)