The earth is middle-aged according to the authors of "The Life and Death of Planet Earth."

In their compelling book 'The Life and Death of Planet Earth,' Geologist Peter D. Ward and Astronomer Donald Brownlee describe a planet in late middle age on a trajectory toward a lifeless end.

Over the course of nearly 300 pages, Ward and Brownlee take a look at our planet and its inhabitants. They chart the Earth's formation, the catastrophic events that shaped its history, and the rise of life, and finally the evolution of higher life forms.

The death of our planet won't pretty or quick. Our planet will suffer the decline of one life-sustaining system after another, eerily similar to that of our own mortal human bodies.

"History," write the two University of Washington professors, "will begin to run backward as Earth's environment eventually slips toward the simple ecology of hundreds of millions of years ago. This decline, we assert, ... has already started. Biologically, Earth has already peaked -- perhaps as long as 300 million years ago."

Eventually, the Earth and Sun will conspire to melt the ice, setting the stage for planetary death by fire.

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