The Moon · Observing
Libration
Say it: ly-BRAY-shun IPA: /laɪˈbreɪʃən/ noun
Libration: The changing orientation of the Moon as viewed from Earth, which makes it appear to rock.
The Moon keeps roughly the same face toward Earth, but our viewing angle changes. Over time we can peek beyond the edges visible on any one night.
- Example
- Favorable libration brought a feature near the lunar edge into clearer view.
- Why astronomers use it
- It helps explain and predict which lunar surface features can be seen from Earth.
- Tiny cosmic connection
- Most familiar lunar libration is a viewing-geometry effect; it is not simply the whole Moon physically wobbling back and forth.
Observatory The Moon Observing
Where to check it
Written for Cool Moon Facts in its own words; the sources cover the same idea in more depth.