How refreshing to read a message of doom that doesn't suggest it is all our fault or that, if we would just get off our collective butt and do something, the planet could be saved.

The authors of this introduction to the new science of astrobiology (combining those extreme-view disciplines, deep-space astronomy and micro-biology) say the future is already written in the stars, and can be read in the universe around us.

Just as we accept our own death, so we must accept that the whole universe is on a similar journey - including stars like our sun and planets like earth.

These two respected US professors explain in lay-language that the earth has been around for 4.5 billion years and can expect to last another 7.5bn. Complex lifeforms, however, have been here only a fraction of that time, actually peaked in fecundity 300 million years ago and will be gone in 500 million. If the earth's lifespan is a single day, the Age of Animals is an 8-10am interlude in a long geological story.

The joy of writing books about the next billion years is that no one will confront you with your mistakes, although Ward and Brownlee, judiciously pepper their text with perhapses, maybes and coulds.

Their intelligent guesses are bad news for religion and the science-fiction industry, but the inevitable demise of humanity, animal life, the Earth and our solar system shouldn't depress us too much. Once we come to terms with our individual mortality, Armageddon is only another step down the road.

Perhaps the most frightening prospect is the traces we might leave behind when life perishes. Since 1920, we have been blasting out radio waves through the universe with every television, radio and cellphone broadcast.

What if some far distant civilisation, billions of years from now, should pick up Davina McCall and Big Brother, and judge us by those fossil records? That really would be a doomsday scenario.