Delta Cephei, found by John Goodricke in 1784, was only the second Cepheid variable discovered. It is very important because its distance is extremely well known. This is partly because it is in a star cluster, close enough for the precise Hubble Space Telescope/Hipparcos parallaxes to give a good result. As a result, it is known as a "fundamental distance calibrator", or absolute candle. Delta Cephei is a classical, or type I, Cepheid variable.