If you want to measure how big a stick is, you can use a ruler. Want to know how tall a windmill is? Don't waste time climbing to the top with a long measuring tape. Instead, use the old shadow trick--measure the length of a yardstick's shadow, then measure the windmill's shadow and use ratios to figure out the windmill's height. Even though the windmill is big and intimidating, you can find out its size while remaining safely on the ground. This is the first example in science author Kitty Ferguson's fine book Measuring the Universe
, and it sets the reader's brain firmly on the right track for understanding.
The topic here is measurement of faraway, distant, difficult things. Starting with Eratosthenes, who found a way of measuring the earth's circumference, and continuing through to modern astrophysicists' quest to measure the universe itself, Ferguson takes us on a full tour of the seemingly immeasurable. Readers are treated to enthusiastic chapters covering all the basic steps astronomers (dating back to Aristarchus of Samos) have taken to understand the arrangement of astronomical objects. How big are stars? Is that black hole moving toward us or away from us? Where is the edge of everything? And how big will the universe get before it stops expanding? You'll meet the men and women who have sought answers to these seemingly impossible questions in this accessible history. Ferguson brilliantly illuminates their personal quests and demonstrates the usefulness of each discovery in driving the next attempt to measure the universe. --Therese Littleton
From Publishers Weekly
When you wish upon a star, do you ever consider that the bright one over there in the Hyades might be closer than the one in the Big Dipper that you usually wish on? Or that your wish might get there faster? Although even the closest star (Proxima Centauri) is so far away (25 1/4 trillion miles) that humanity will probably never travel to it, Ferguson (Prisons of Light: Black Holes) demonstrates why knowing its distance from us is important, and not just for reasons of wish fulfillment. For only by drawing an accurate scale map of the universe, she explains, can scientists estimate its age, one of the most hotly contested issues of our time. Ferguson begins with attempts in antiquity to establish the distance to the sun and the five planets seen by the naked eye. She discusses the findings of Copernicus, Kepler and Galileo, and how each drew on the others' work. Her simple explanations of the discoveries of stellar parallax, the Doppler effect and redshift, and of absorption spectra make important scientific concepts clear for general readers. She goes on to elucidate how astronomers determine how far away other stars are by using a type of star called Cepheid, as well as the spectacular stellar self-destructions known as supernovae as "standard candles." To conclude her engrossing survey, Ferguson covers some of the paradoxes that scientists confront, such as that some estimates of the age of the universe have determined that it is younger than some of its oldest stars, and that the amount of observable mass in the universe is only about 10% of what should be there. (July)
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