Just two decades after the search for planets outside our solar system began, scientists have found more than 700, a French astronomer says.

Astrobiologist Jean Schneider of the Paris-Meudon Observatory, who maintains the Extrasolar Planets Encyclopedia database, said the tally now stands at 702, SPACE.com reported Friday.

The count has been growing quickly lately and will increase by hundreds, or perhaps thousands, of new alien planets in the near future, astronomers said.

The first alien worlds, two planets orbiting a rotating neutron star, or pulsar, about 1,000 light-years from Earth, were detected in 1992.

One instrument in particular has bagged the lion's share of known exoplanets. Since its launch in 2009, NASA's Kepler space telescope has identified 1,235 possible planets.

And astronomers say a goodly number of them appear to orbit in their stars' habitable zone, where liquid water -- and perhaps life as we know it -- could exist.