Measuring the Universe: Our Historic Quest to Chart the Horizons of Space and Time

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)