#astronomy 

A lunar phase is the apparent shape of [[The Moon|the moon]]

![[Pasted image 20240622000645.png]]Third quarter = last quarter

![[Pasted image 20240622000856.png]]

## Lunar month
### Synodic month
The synodic month (lunation) is the average period of the Moon's orbit with respect to the line joining the Sun and Earth: 29 days, 12 hours, 44 minutes. This is the period of the lunar phases.

### Sidereal month
The sidereal month is the period of the Moon's orbit as defined with respect to the [[Celestial sphere|celestial sphere]] of apparently fixed stars: it is the time it takes the Moon to return to a similar position among the stars: 27 days, 7 hours, 43 minutes.