Magnituud

Magnituud is a term used in several languages, notably Estonian, to denote the size, extent, or brightness of something. In mathematics and physics, magnituud refers to the magnitude or norm of an object such as a number, vector, or complex number. For a vector v = (x1, x2, ..., xn), magnituud is the Euclidean norm: |v| = sqrt(x1^2 + x2^2 + ... + xn^2). For a complex number z = a + bi, magnituud (modulus) is |z| = sqrt(a^2 + b^2).

In astronomy, magnituud or magnitude describes the brightness of celestial objects. Apparent magnitude measures how bright an object appears from Earth, while absolute magnitude expresses intrinsic brightness at a standard distance of 10 parsecs. The scale is logarithmic and inverse: smaller (or more negative) magnitudes indicate brighter objects. A difference of five magnitudes corresponds to a brightness ratio of 100. The Sun has an apparent magnitude of about -26.74, while the full Moon is around -12.74.

In seismology, the magnitude concept is used in scales such as the moment magnitude Mw to quantify the size of earthquakes. These scales are logarithmic and roughly relate energy release by a factor of about 31.6 per unit magnitude.

The term magnituud is etymologically rooted in Latin magnitudo, meaning greatness or size, and it is used across disciplines to express a measure of size, length, brightness, or impact. Depending on context, the exact definition and units vary, but the common idea is a single numeric measure of extent.