Washington ? The Hubble Space Telescope may have discovered as many as 100 new planets out beyond our solar system orbiting stars in the Milky Way galaxy, astronomers say.

If confirmed, that would double the known population of alien planets since the first one was detected nine years ago, according to Steven Beckwith, the director of the Space Science Telescope Institute in Baltimore, which operates the Hubble.

Astronomers are coming to believe that almost every sunlike star in the galaxy, and probably in the universe, is accompanied by one or more planets like our solar system, vastly increasing the chance that some form of extraterrestrial life could exist.

Hubble’s expected harvest of previously unknown planets stems from a sweep of thousands of stars in the domelike bulge protruding above the flat disk of the Milky Way.

For seven straight days in late February, Kailash Sahu, an astronomer at the Baltimore institute, used the 14-year-old telescope to monitor the amount of light streaming from the brightest stars.

A tiny decrease — less than a tenth of 1 percent — in the light was a sign that something, perhaps a planet, was passing in front of the star. A similar phenomenon entranced millions of earthlings when Venus transited the sun June 8.

Sahu is now employing an older planetary-detection method to confirm that the transiting objects are really planets and not something else, such as dwarf stars or clouds of interstellar gas.