Cepheid Variable in Spiral Galaxy

A Cepheid is a star that varies in light intensity over regular, measurable periods. The period of pulsation is directly related to a Cepheid's intrinsic brightness making observations of these stars a powerful tool for determining distance. This animation shows a Cepheid variable star varying in brightness in the arm of a spiral galaxy. Note: This animation shows a Cepheid variable star varying in brightness in the arm of a spiral galaxy. Animator: Dana Berry (Skyworks Digital). Writer: Michael