Transcript: In the late eighteenth century the young English amateur astronomer John Goodricke discovered brightness variations in the star Algol while he was only seventeen years old. Soon afterwards he observed Delta Cephei carefully enough to find regular brightness variations with a timescale of five days and eight hours. The Royal Society awarded him a medal for his work, and he quickly became noted in the scientific community. Goodricke was born deaf and unable to speak in an age when most deaf-mutes were consigned to asylums and rarely did any useful work. Unfortunately Goodricke died of pneumonia at age twenty-one due to his excessive time spent outside making difficult observations. Goodricke had discovered regular short period variable stars. The two most notable categories of these stars are Cepheid variables with periods of one to fifty days, Polaris is a prime example, and RR Lyrae variables with periods in the range of one to twenty-four hours.