Lunar eclipses typically happen about two times every year. The maximum number of lunar eclipses in a single year can be as many as five, though this is rare. Total lunar eclipses occur on average every 2.5 years at any given location. Partial lunar eclipses usually occur once a year or once every two years. The reason lunar eclipses don't happen every month is due to the tilt of the Moon's orbit relative to the Earth's orbit, causing the Moon to usually pass above or below Earth's shadow during a full moon. To summarize:
- Average lunar eclipses per year: 2
- Maximum lunar eclipses per year: 5 (rare)
- Average frequency of total lunar eclipses at a location: every 2.5 years
- Partial lunar eclipses frequency: about once a year or once every two years
This phenomenon occurs only during a full moon when the Moon passes through Earth's shadow, but the orbital tilt prevents it from happening every month.
