Just finished reading a slim volume called Miss Leavitt's Stars: The
Untold Story of the Woman who Discovered How to Measure The
Universe, by George Johnson. WW Norton. 2005.

July 4, 1868 – December 12, 1921: Died from stomach cancer at the
age of 53.

First I present below the (non-copyrighted) info from Wikipedia -
just because it is more succinct than the information scattered
throughout Johnson's book.

...Leavitt began work in 1893 at Harvard College Observatory as one
of the women "computers" brought in by Edward Charles Pickering to
measure and catalog the brightness of stars in the observatory's
photographic plate collection. She noted thousands of variable stars
in images of the Magellanic Clouds. In 1908 she published her
results in the Annals of the Astronomical Observatory of Harvard
College, noting that a few of the variables showed a pattern:
brighter ones appeared to have longer periods. After further study,
she confirmed in 1912 that the variable stars of greater intrinsic
luminosity—actually Cepheid variables—did indeed have longer
periods, and the relationship was quite close and predictable.

This relationship provided an important yardstick for measuring
distances in the Universe, if it could be calibrated. One year after
Leavitt reported her results, Ejnar Hertzsprung determined the
distance of several Cepheids in the Milky Way, and with this
calibration the distance to any Cepheid could be determined. When
Cepheids were detected in other galaxies such as the Andromeda
Galaxy, the distance to those galaxies could also be determined.
These distances settled the debate on whether the galaxies were
external to the Milky Way or part of it.

Leavitt worked sporadically during her time at Harvard, often
sidelined by health problems and family obligations. But by 1921,
when Harlow Shapley took over as director of the observatory, she
was head of stellar photometry. She succumbed to cancer by the end
of that year.

Little is known about Leavitt's life, according to Johnson, and
indeed in his own book, of 130 pages (not including 30 pages of
acknowledgements, notes, bibliography and index), she gets at the
most about 10 pages worth of text. Unfortunately, Leavitt left no
diaries and few letters, for anyone to do research into her life.

Johnson's title is a misnomer, therefore, specifically used jut to
draw in those people who want to read about the lives of pioneer
women scientists (i.e., me) - most of the book deals with the use
male astronomers (Pickering, Shapley) made of her work.

The book is by no means uninteresting, it explains the astronomical
principals of parallax and the Cepheids, etc. in simple language -
it's just annoying that so little time is devoted to Leavitt -
although apparently this is unavoidable because of the scarcity of
information about her private life. However, it would've been
interesting to learn more about the other female "computers" at the
observatory - who made 30 cents a *day* doing the comparison work
from which great discoveries were announced by the astronomers.