24 of 26 people found the following review helpful
If you look up at the night sky (unobscured, if possible, by city lights), you cannot help but see that some stars are bright and some are barely perceptible. There are explanations for these differences; a bright star may be an ordinary star but simply closer, or a bright star might be at an ordinary distance but simply bigger. A big part of the challenge of astronomy is trying to figure out just this sort of problem, because it involves basic measurements of our universe. One of the greatest breakthroughs on the way to understanding how to measure stellar distances was made by Henrietta Swan Leavitt, and if you have never heard this name, there are many reasons, all of them a little embarrassing. In _Miss Leavitt's Stars: The Untold Story of the Woman Who Discovered How to Measure the Universe_ (Atlas Books / W. W. Norton), George Johnson has brought Leavitt to us, so that we can consider what she accomplished, and why she remains obscure. There is not actually much material on Leavitt here; this is a small book to begin with, and few of the pages actually have to do with her life. Johnson himself says she deserves a proper biography, but unless some heretofore secret material is found, she won't get one. She didn't leave diaries or memoirs, and there are few letters. What she left astronomers was a celestial yardstick, and it was used to change fundamentally our knowledge of the size and age of the universe we inhabit.
Photography became a great help in astronomy, and eventually Harvard had a half million glass plates that were a precise a record of the night sky. But this was very raw data. To analyze the images, the director of the Harvard observatory, Edward Pickering, employed computers. A computer at that time was not an electronic gadget, but a human, a person who was hired to compute, when computing was monotonous and repetitive work. Leavitt was merely a computer, paid a minimal wage to do the drudgery of looking at the plates and toting up the brightness, color, and position star by star. Astronomy certainly was benefited by Leavitt's powers of observation, but she is one of the greats in astronomy because she organized her observations in an exceedingly useful and explicatory way. She concentrated her thinking on variables known as Cepheids (the first one having been found a hundred years before in the constellation Cepheus). She tallied up these stars, their brightness, and their rate of variation, and found that rate varied with brightness. A Cepheid that had a certain rate had a certain brightness, and this was the case whether it was distant or close. If two stars of the same rate appeared to have different brightness, it was only a matter of their different distances. Astronomers had a new measuring tool.
Johnson's book explains how over the centuries astronomers first were able to measure the size of the Earth, then the distance to the Moon, to the Sun, to more distant stars, and to galaxies. He shows Leavitt's finding as essential in the later measurements, and his explanations are clear and make good use of imaginative analogies. He also shows how her work was fundamental in changing our knowledge of the basic structure of the universe. We had already come to understand that we were not the center of the solar system, but Leavitt's discovery was crucial in our further understanding that the Milky Way was not the entire universe and that there were "island universes" or other galaxies beyond it. This book is actually a small history of astronomy. It is sad that it can contain so little about Leavitt herself. She never married and she died when she was 53. The clearest description we get of her personality is a few lines from her obituary: she "took life seriously," but "was possessed of a nature so full of sunshine that, to her, all of life became beautiful and full of meaning." Part of the problem, of course, was that as a woman, even though she has every right to be known as an important astronomer, she was assigned to lowly tasks. Even so, she carried them out with thoroughness and with the clarity of observation and spark of imagination that brings on scientific revolutions.
7 of 8 people found the following review helpful
on June 10, 2007
Allan Sandage, the respected astronomer and protégé of Edwin Hubble, once said: "What are galaxies? No one knew before 1900. Very few people knew in 1920. All astronomers knew after 1924."
Miss Henrietta Leavitt died in 1921. Working for years at the Harvard College Observatory under the noted astronomer Edward Pickering, this nearly forgotten observatory assistant, a 'computer' (one that does computations by hand), provided a tool critical to unraveling the most basic question facing astronomers in the early twentieth century. Was the Milky Way essentially the entire universe, or was the Milky Way just one of many large clusters of stars? These hypothetical clusters went by various names: island universes, nebulae, and galaxies.
How could one demonstrate that some stars were in a nearby cluster, while others were actually much farther away? Triangulation methods, a trigonometric approach, only worked for the sun and a few nearby stars. Is a dim star a bright star that is far away, or is a dim star simply a dim star that is nearby?
This short book, Miss Leavitt's Stars, is less biography, and more history and science than the title might suggest. Too little is known about Henrietta Leavitt herself. We do know that Miss Leavitt carefully analyzed the brightness of variables stars (those that brighten and dim over some period) in the Small Magellanic Cloud. Subsequently, she discovered a remarkable relationship between the brightness of individual stars and the lengths of their periods. The brighter the variable star, the longer the period. Furthermore, since the Magellanic variables are probably all about the same distance from the earth, their periods are apparently associated with their actual light emission.
What all this means is that by measuring the period (the rhythm of brightening and dimming) one could determine the intrinsic brightness of a variable star. In turn, by comparing this calculated intrinsic brightness to the observed brightness an astronomer can determine how far away the star actually is.
This breakthrough fueled the competition among astronomers to resolve the size of the universe. The ongoing debate between Harlow Shapley and Edwin Hubble dominates the second half of this short book. Hubble wins, and the concept of a galaxy becomes commonplace. Even more remarkable, distant galaxies are shown to be accelerating away: the universe is expanding at a rate determined by the Hubble Constant. I like the quote about Edwin Hubble from a hometown newspaper: Youth who left Ozark Mountains to study stars causes Einstein to change his mind.
George Johnson writes with a clarity and precision not always found in science books for the layman. Miss Leavitt's Stars is a delightful blend of biography, history, and astronomy.
Trivia: I was once a computer for a month. As a new geophysicist, I worked on a seismic crew in the Louisiana swamps for a year, rotating between various crew positions each month to gain first hand experience. While holding the job title 'computer', I analyzed by hand raw data as it was collected, essentially quality controlling seismic data that was slated for intense processing on large mainframe computers. Unlike Miss Henrietta Leavitt, my hand calculations were not entirely manual. I did possess a hand calculator, a tremendous advantage. It is difficult to imagine the meticulous measurements and calculations carried out day after day, night after night, by Miss Leavitt.
4 of 4 people found the following review helpful
on June 2, 2006
This is a great little book. In 130 pages of well-crafted prose, the author recounts the history of one of the most exciting periods in modern astronomy. Concentrating mainly on the early decades of the twentieth century, he explores astronomers' efforts to understand the size and structure of the universe. As the book's title suggests, Miss Leavitt's stars, i.e., Cepheid variables, play a very important role in this quest. However, according to the author, so little is known about Miss Leavitt's life per se that the book's subtitle is an exaggeration: the book is more about early twentieth century astronomy and much less about Miss Leavitt's life. Scientific principles are very clearly explained using simple analogies. No mathematical formulas are used anywhere in the book - an advantage or a disadvantage, depending on your point of view. Written in a most engaging style, this book would be of interest to anyone, but especially science/astronomy buffs.
4 of 4 people found the following review helpful
on July 25, 2005
This somewhat short book is a treasure trove for anyone seeking an inside look at astronomy early in the 20th century. The author presents some interesting insights into the intertwined careers of Henrietta Swan Leavitt, Pickering, Shapely and Hubble.
4 of 5 people found the following review helpful
on July 3, 2005
No study of history - no study of scientific discovery - is complete without recognizing how women helped shaped our knowledge of the world, the heavens and society. As more and more women, such as "Miss Leavitt," are recognized for their dediction to scientific discovery and other endeavors - just imagine what wonderful insights we have yet to learn! Too many of these stories remain untold. Thank you George Johnson for telling this one. "Miss Leavitt's Stars" belongs on every young woman's bookshelf and should be read to even the youngest girls - so she, too, may reach for the stars. (Review by: Marion E. Gold, author of "Top Cops: Profiles of Women in Command" and "Personal Publicity Planner: A Guide to Marketing YOU.")
1 of 1 people found the following review helpful
on March 4, 2013
This short book (130 pages of text) is an essential addition to the history of astronomy. Very little data is available about Henrietta Leavitt, the woman who made one of the most important discoveries in astronomy. As the author notes, she left no diaries, no boxes of letters, no memoirs, and she did not brag about her work. Given the lack of information available, George Johnson does a great job of weaving what we do know of Leavitt's life and work into the story of astronomy in the early 20th century. Johnson is a gifted writer. Sentences and paragraphs are easy to follow; all the references to the people discussed in the book are clearly explained. His use of the "village in the canyon" analogy to explain the strengths and weaknesses of determining parallax is excellent. The relationship of Leavitt's incredibly detailed work on Cepheids to Hubble and Shapley is developed in a way that shows an often gross omission of credit on their part, yet the book is not about blame. Johnson points out the sexist hierarchical structure in astronomy at the time and the role of women as human computers. (They were actually called "computers.") Hubble and others, who should have gone beyond that social limitation, simply assumed that their human computer was not to be given credit. Johnson lets the facts about Leavitt's work speak for themselves and the reader can draw his or her own conclusion. It is true that we never get to know Leavitt in any deeply personal way but that can hardly be held against the book. Instead of speculating based on nothing, Johnson takes the information that we do have and turns this into a testament to a brilliant woman whose work became foundational for modern astronomy. The book is well worth obtaining for anyone interested in the history of science.
2 of 2 people found the following review helpful
on August 10, 2013
I found this to be a wonderful read. It gives you an insite to those who worked so hard in the field of astronomy without proper recognition. For those who are interested in the history of U.S. astronomy I highly recommend this book
3 of 4 people found the following review helpful
on August 15, 2005
In this age of specialization, it is downright easy to walk away with a liberal arts degree and still be ignorant of many of the arts and sciences. For me, a lit major, a book like MISS LEAVITT'S STARS is the perfect ticket to the ongoing task of plugging the immense gaps in my science education. This slim volume holds accessible explanations of formulae and theory, the history of modern astronomy and animated profiles of the key figures all wrapped up with a lucid, friendly voice.
The author, George Johnson, was set to write about the key factor that moved the science of astronomy into the business of measuring the universe when the obscure figure of the person who identified the measurement instrument beckoned, and so he trained his gaze on her. Henrietta Swan Leavitt, the picture of an educated, late Victorian spinster, was one of the chorus of mostly female, lowly paid "computers," those who performed the tedious work of analyzing the rising stack of astrological photographs produced by cameras attached to telescopes. It was she who identified the Cepheid stars, whose luminosity properties yielded a marker that propelled astronomy into the search for the size, age and origins of the universe. Johnson had few extant records of the quiet Miss Leavitt to go on, but he succeeds in fleshing her out amidst the plus-sized egos of Edwin Hubble and Harlow Shapley who took her work and ran in two different directions with it. As Johnson chuckles, we know whose ideas prevailed by the name given the headlining telescope circulating the earth these days, though in the early 20th century, Shapley held sway at Harvard, where Leavitt labored. Leavitt, who died of cancer in 1921, also prevails, though gently, often in footnotes but also honored with a topographical feature of the moon named for her.
I very much enjoyed this round trip back to the scientific frontier. This is the first volume I've read in Norton's Great Discoveries series, and on the basis of this book, I'll gladly go for more.
1 of 1 people found the following review helpful
on June 26, 2007
This book should be a must read for any high school or college Astronomy
or natural science class. Its an easy read (few hours) of the remarkable
Ms. Henrietta Leavitt, who discovered that stars at a fixed distance
(in our closest neighbor galaxy, the large Magellanic Cloud) vary in their
apparent (and thus true) brightness with a period proportional to their
average brightness. Thus by measuring the time (typically a few days)
between successive peaks in brightness, the intrinsic brightness, or
luminosity, could be accurately inferred. And knowing this, for such a
star in a distant galaxy, the distance to that galaxy followed from
simple comparison with the apparent brightness. This allowed the
distance scale, or cosmic yardstick, to be determined for the first time,
all from the patient and largely unrecognized work of woman "computer"
(as they were then called) at the Harvard Observatory painstakingly
measuring glass negative photographic plates of the southern sky taken
with Harvard telescopes in Peru and elsewhere. Johhson's book is a
beautifully written account of scientific discovery, told in a clear but
1 of 1 people found the following review helpful
on October 17, 2007
Henrietta Leavitt was an incredible individual. She made some of the greatest discoveries in astronomy during the 20th century, however, very little has been written about her enigmatic life. Miss Leavitt's Stars: The Untold Story Of The Woman Who Discovered How To Measure The Cosmos by George Johnson attempts to fill in what is known about Leavitt. For those of you that have a passion for historical astronomy I would recommend this book. It is easy reading and not a large book to read. It gives a great overview of some of the scientific rivalry between other astronomers of the era, such as Harlow Shapley & Edwin Powell Hubble. The only thing I found slightly disappointing about the book is it's limited information about Leavitt. Of course, this is of no fault on the authors part, but due to poor records kept about Leavitt's life at the time. Henrietta Leavitt lived in a time when astronomy and science in general was dominated by men, and this book is a fitting tribute to a woman who slowly helped to break down some of those barriers for early female scientific pioneers.