Henrietta Swan Leavitt

Henrietta Swan Leavitt was born in Massachusetts in 1868 and studied at what later became Radcliffe College.

She worked at the Harvard College Observatory, where women known as computers examined photographic plates and measured stars.

Leavitt studied Cepheid variable stars in the Magellanic Clouds and noticed that brighter Cepheids tended to have longer periods of variation.

Because the stars she studied were approximately at the same distance, the pattern revealed a relationship between the period of variation and true luminosity.

If astronomers know how luminous a Cepheid truly is, they can compare that with how bright it appears from Earth.

The difference allows them to estimate distance, turning Cepheids into important standard candles for astronomy.

Later astronomers used Cepheids to determine that some spiral nebulae were actually separate galaxies far beyond the Milky Way.

That connects Leavitt's work directly to Edwin Hubble and the expansion of humanity's known universe.

TransitSatellite's future Galaxy experience will need stories that explain not only where stars and galaxies are but how astronomers know their properties and distances.

Leavitt provides one of the clearest historical foundations for that kind of understanding.

Leavitt did not travel to another star or galaxy. She found a relationship in observations.

That relationship allowed later astronomers to measure distances on a scale that had previously been extremely difficult to determine.