IN JANUARY NASA, America's space agency, released a massive,
high-resolution image of Earth from space, a 64-megapixel update
to the iconic "blue marble" shot snapped by Apollo 17 astronauts
on their way to the moon in 1972. Gone was the monochromatic
ocean of the Apollo era. It now glistens with a range of blues,
from aquamarine to dark navy. Yet Earth was not always so
beautiful. In its infancy, 4.5 billion years ago, the planet was
a volcanic wasteland. It did not even have a moon.  Since then,
Earth has grown in fits and starts. Its oceans, products of
giant, moisture-spewing volcanoes, formed quickly, but its
continents took hundreds of millions of years to surface—and
billions more to acquire a thin layer of green. For eons, the
planet veered wildly between extremes, impersonating a range of
celestial bodies. The first oxygen-producing microbes rusted
Earth to a Martian shade of red; later on, it froze, turning
white like the moon.   In his new book, "The Story of Earth",
Robert Hazen, a geophysicist at