When you look at moonrise/moonset calendars how is it that somedays the moon sets without rising?

Because of its motion around the Earth, the Moon sets and rises 50 minutes later each day. As a result, there is a day in every lunar cycle when the Moon skips a day, rising late on one day and setting early two days later.

The moon moves in its orbit so that there are 24.9 hours between moonset and the next moonset. A full cycle of set, rise, and set again sometimes does not fit in 24 hours.

Here's the moonrise/set data for Espanola, ON (46d 15m N, 81d 46m W) for June 2012 from the UNSO calculator http://aa.usno.navy.mil/data/docs/RS_OneYear.php I've added 1 hour to the times to give local daylight savings time Date Rise Set 07 2356 0913 08 [None] 1026 09 0026 1135 10 0052 1242 The rise times are always given first and the set time second for any given day. You need to be careful to look at the times to see which is happening first. Thus, on June 7 the moon sets at 0913 (having risen late in the evening on June 6). It then rises at 2356 on June 7 and sets at 1026 on June 8. The next moonrise occurs shortly after midnight, at 0026 on June 9 and the moon then sets at 1135 on June 9. And so on. As others have pointed out, the cycle from one moon rise to the next is around 25 hours (give or take depending on the time of year) and thus there may not be a moonrise (or moonset) on a given day but rather occurs just before midnight on the day before and then just after midnight on the day after.