About Henrietta Leavitt

Henrietta Leavitt was an American astronomer working at the Harvard Observatory. She catalogued and studied Cepheid variable stars in the Small Magellanic Cloud. These are pulsating stars named after delta Cephei (in the constellation Cepheus) -- the first one discovered. If you chart the brightness of a Cepheid, you notice that it varies in a steady, rhythmical period (over days or weeks). Leavitt noticed that the average brightnessof these stars was related to the period.

Her work established the so-called "period-luminosity" relationship for all Cepheids, which, in turn allows astronomers to calculate the distance to the stars -- and the galaxies in which they exist. It was a systematic search for Cepheids in the galaxy M100 by the Hubble Space Telescope, and the application of Leavitt's work in calculating a new value for Hubble's Constant that allowed astronomers to announce a new age for the Universe in 1994 -- somewhere between 8-12 billion years.

(For more information on Cepheids and their role as distance indicators, see Astronomy!, by James Kaler, pp. 374-378, HarperCollins, 1994)

I've always wanted to dedicate a space theater to a woman astronomer and then use it to teach people about the beauty of the cosmos. The Online Planetarium Show is a sort of guided tour of the universe where you'll see the stars and planets and galaxies as astronomers see and study them " along with some poetic and explanatory text. So, play some relaxing space music and take a journey through the cosmos.