page_title: Delta Cephei
section_title: Discovery
hierarchical_section_title: Delta Cephei / Discovery
context_page_description: Delta Cephei is the Bayer designation for a quadruple star system located approximately 887 light-years away in the northern circumpolar constellation of Cepheus, the King. At this distance, the visual magnitude of the star is diminished by 0.23 as a result of extinction caused by gas and dust along the line of sight. It is the prototype of the Cepheid variable stars that undergo periodic changes in luminosity.
context_section_description: Delta Cephei was discovered to be variable by John Goodricke during 1784. He describes his first observation on October 19, 1784, followed by a regular series of observations most nights until December 28. Further observations were made during the first half of 1785, the variability was described in a letter dated June 28, 1785, and formally published on January 1, 1786. This was the second variable star of this type, with eta Aquilae being discovered just a few weeks earlier, on September 10, 1784.
caption: Image of Delta Cephei, in the center
exif: {}