A Lunar eclipse will occur only at full moon. This does not happen every month because the moon has to cross Earth’s ecliptic when it is full. This normally happens twice a year during eclipse seasons.
Astronomy Fact of the Day: January 11, 2019

A Lunar eclipse will occur only at full moon. This does not happen every month because the moon has to cross Earth’s ecliptic when it is full. This normally happens twice a year during eclipse seasons.