Bells (VIDEO) Carnegie Institution for Science This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption Because of a difference in their distances, two bells appear to be the same size. But larger bells vibrate at lower frequencies than smaller bells. Listening to both, you can deduce that the bell in the tower has a deeper tone -- a lower frequency -- and must be larger in size and therefore farther away. In this analogy the bells are two Cepheid variable stars that have different periods. If the two Cepheids had the same apparent brightness, the one with the longer period (lower frequency) must be farther away. Credit Carnegie Institution for Science Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.