Displacement of the spectral lines of system (atoms, molecules) due acting of external magnetic field.

The angle at the center of the Earth between a point vertically above an observer and an object such as the Sun. The solar zenith angle is zero if the Sun is directly overhead.

It is a faint, roughly triangular shaped glow of light extending away from Sun. The spectrum of the zodiacal light is the same as the solar spectrum, reinforcing the deduction that it is merely sunlight reflected by dust in the plane of the planets.

Refers to east-west direction.