Earth-like planet find 'imminent'

Astronomers say they are on the verge of finding planets like Earth orbiting other stars, a key step in determining if we are alone in the universe.

A top Nasa astronomer and other leading scientists say that within four or five years they should discover the first Earth-like planet where life could develop, or may have already.

A planet close to the size of Earth could even be found this year if preliminary hints from a new space telescope pan out.

At the annual American Astronomical Society conference in Washington this week, each discovery involving so-called "exoplanets" - those outside our solar system - pointed to the same conclusion: quiet planets like Earth where life could develop are probably plentiful, despite a violent universe of exploding stars, crushing black holes and colliding galaxies.

Nasa's new Kepler telescope and a wealth of new research from the suddenly hot and competitive exoplanet field generated noticeable buzz at the convention.

Scientists are talking about being at "an incredible special place in history" and closer to answering a question that has dogged humanity since the beginning of civilisation.

"The fundamental question is: are we alone? For the first time, there's an optimism that sometime in our lifetimes we're going to get to the bottom of that," said Simon "Pete" Worden, an astronomer who heads Nasa's Ames Research Centre.

"If I were a betting man, which I am, I would bet we're not alone -- there is a lot of life."

Even the Roman Catholic Church has held scientific conferences about the prospect of extraterrestrial life, including a meeting last November.