Definition:Parallactic Angle

Definition

Let $x$ be a point on the celestial sphere.

Let $\SS_1$ be the arc of the great circle between $x$ and the zenith.

Let $\SS_2$ be the arc of the great circle between $x$ and the north celestial pole.

The parallactic angle is defined as the (spherical) angle between $\SS_1$ and $\SS_2$.

Symbol

The usual symbol used to denote parallactic angle is $q$.

Also see

• Results about parallactic angles can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): parallactic angle
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): parallactic angle