Secrets of the Universe: How We Discovered the Cosmos [Hardcover]

We came to our current scientific understanding of the universe over centuries, triumphing over superstition and demonstrating that for investigating nature, nothing beats careful observations and measurements when they are harnessed to our inherently curious natures. Quietly we built up a storehouse of facts and explanations for them, and sometimes the effort was punctuated by the excitement of discovery. Paul Murdin knows about this personally. In the introduction to his _Secrets of the Universe: How We Discovered The Cosmos_ (The University of Chicago Press), he explains that as a working astronomer in the seventies, he found a star that was responsible for a beam of x-rays that had previously been detected, and that the star was a result of a supernova explosion 3,000 years ago. He was delighted to realize that no one else in the world (and maybe no other being in the galaxy) knew what he did about the star. He admits this was a tiny discovery although his book is about the big ones, but the people who made the big discoveries had the same sense of exultation. Edward Charles Pickering was director of Harvard College Observatory, and he had as a scientific assistant his former maid Williamina Fleming who had become a full-fledged astronomer. In 1910 they were visited by Henry Norris Russell, an astronomer from Princeton, and the three of them started wondering about the temperature of a particular star, and it led to a revelation. Russell wrote, "At that moment, Pickering, Mrs. Fleming and I were the only people in the world who knew about white dwarfs." In 1639, Jeremiah Horrocks and his friend William Crabtree looked for the black dot of Venus to inch its way across the disk of the sun, which Horrocks had calculated would happen by using Kepler's tables. Horrocks wrote of Crabtree's scientific ecstasy at confirmation of the calculations, that he "... stood for some time motionless, scarcely trusting his own senses, through excess of joy; for we astronomers are of a womanish disposition and are overjoyed with trifles."

There are plenty of surprising human stories here. When the Nazis overran the Netherlands, Dutch astronomers were inconvenienced - observing the skies at night was a violation of curfew. Astronomer Jan Oort encouraged his students to do theoretical studies if they couldn't do observational ones. They were able to calculate the radio waves that ought to have been emitted by hydrogen atoms, and after the war was over they were among the ones to confirm experimentally that this was so. Being able to plot the hydrogen waves enabled us to map our galaxy. During the Cold War, satellites were sent up to look for the gamma ray bursts that would mean there had been a nuclear explosion. No one was ready to find such bursts happening routinely week-by-week; it wasn't nuclear tests but some mysterious natural phenomenon that no one had expected. The astronomers who used satellite data to prove that the bursts came from cosmic explosions couldn't originally print all their data, because that would have told our enemies what our satellites were able to do. More recent observations show that gamma ray bursters in their few seconds of emission send out as much energy as is in a supernova. The rings of Saturn began to be understood. Galileo, with his primitive telescope, saw them as "handles" or large moons of the planet. In 1656, the Dutch astronomer Christiaan Huygens was the first to see the rings. The rings were spectacular, but begged for an explanation. The French mathematician Laplace in 1787 suggested that since a single solid ring could not orbit the planet, that it was instead a collection of thin solid ringlets. In 1849, another French scientist named Roche calculated that any solid (a moon or rings) that close to Saturn would break up under the planet's gravity. The Scottish physicist James Clerk Maxwell showed that the rings could only be unconnected particles with different rotation rates depending upon distance from the planet, and in 1895 these different rates were indeed found. Uranus has been found to have more than ten rings, and Neptune has four or five. Even Jupiter has some thin ones. Repeatedly, what we have learned from studying the skies has helped us understand what goes on here below. Spectrograms of sunlight showed that both the Sun and the Earth were made of similar elements, demonstrating that Earth wasn't a particularly special place by chemistry any more than it had been by location. The element Helium was discovered spectrographically on the Sun in 1868 before it was isolated on Earth in 1895.

_Secrets of the Universe_ is a gorgeous, big-format book, with pictures on almost every page, most in color. The chapters move out from the solar system to cosmic physics, to our galaxy, and to the universe beyond. Within the chapters are four-page summaries to tell about supernovae, dark matter, quasars, the greenhouse effect, or the surprisingly revelatory question of why the sky is dark at night (it's because the universe isn't infinite in time or space, silly). Murdin has given lucid explanations in these short segments, and connects them throughout to other segments, showing a surprising unity within the diverse efforts of space exploration. The book is a beautifully illustrated guide to the history and accomplishments of our astronomical quest, exciting to look at and fun to read.

This is a very good overview of astronomy, encompassing the early years and the latest discoveries as well as theories, explained in layman's terms. Accompanied by high-definition photos, it's a great starter for those interested in astronomy.