Candela
SI unit of luminous intensity
A candela is the SI base unit of luminous intensity. It measures how bright something is. It is one of the basic units of science. A light bulb is bright, but the Sun is much brighter, so the Sun has more candelas than the light bulb.
![](http://up.wiki.x.io/wikipedia/commons/thumb/a/a0/Luminosity.png/290px-Luminosity.png)
The frequency chosen for measuring candelas is in the visible spectrum near green. This is a wavelength of about 555 nanometres. The human eye is most sensitive to this frequency, when adapted for bright conditions.
A candela sometimes is called 'candle'.