NASA has spotted hundreds of new planets outside our solar system, many of them similar to Earth, in a discovery that has renewed the possibility of extraterrestrial life.

Six weeks of data gathered by the National Aeronautics and Space Administration's deep-space Kepler probe reveal five new solar systems within the Milky Way as well as 700 bodies that could be new planets, the agency confirmed Sunday.

Scientists say 140 of those bodies are considered "Earth-like," meaning their composition could support the development of simple life-forms.

Still, "it doesn't mean that there's life on them, it doesn't mean that there's atmosphere and water," says Paul Delaney, an astronomy professor at York University.

"What it does mean is that we have objects now that are much more similar to the Earth than we have found to date," he told CTV News Channel on Monday.

Until NASA's announcement, roughly 450 planets had been found outside our solar system in the past 15 years, Delaney said. Most of those planets are completely inhospitable for life, with surface temperatures in the thousands of degrees Celsius.

The discovery has left scientists itching for more information on the new bodies, but Delaney says any further fact-finding will have to be done from a distance.

"You can't get to these objects with spacecrafts -- the closest ones are tens of light-years away and some are literally a few thousands light-years away," he explained. "They are well and truly beyond our technological capability to visit personally."

Modern technologies such as the Kepler probe should provide opportunities to examine the planets, he added. "Kepler's given us the place to look, we'll now look in greater detail," he said.

The Kepler probe was launched to great fanfare in April 2009, but only reached a position to monitor space outside our solar system in June.

The spacecraft examines bodies in the Milky Way through a telescope that includes a 95-megapixel camera.