Richter magnitude scale (including the surface-wave M_s and body wave M_b magnitudes)

Apparent magnitude

Absolute magnitude

Absolute Bolometric magnitude (Symbol M_b)

Moment magnitude scale

Magnitude (mathematics), a measure of the size of a mathematical object:

Magnitude of an eclipse

A scalar object has only magnitude as its defining characteristic.

Absolute Photographic magnitude (Symbol M_pg)

A vector object has both magnitude and direction as its defining characteristics.

A logarithmic measure of the brightness of an astronomical object: