noun
elongation
The angular distance between a planet and the sun as seen from Earth.
Mercury reaches its greatest elongation from the sun this evening.
Etymology
Elongation names a making longer or a separation. Astronomy applies the idea of separation to the angle between a planet and the Sun in the observer’s sky.
More examples
- The chart lists each planet's elongation in degrees.
- At a small elongation, Venus is difficult to distinguish from the sun's glare.
- Mercury's greatest eastern elongations offer chances to see it after sunset.
Forms
elongation · elongations
Similar words
- angular separation
- Can describe any two celestial objects, not just a planet and the sun.