WASHINGTON — European astronomers have found 32 new planets outside our solar system, although none seem habitable.

The announcement by scientists using the European Southern Observatory telescope increased the number of planets discovered outside the solar system to more than 400.

Most planets discovered so far are far bigger, Jupiter-sized or even larger.

Two of the newly discovered planets were as small as five times the size of Earth and one was up to five times larger than Jupiter. Jupiter’s mass is more than 300 times that of Earth’s.

Astronomer Stephane Udry of the University of Geneva said the results support the theory that planet formation is common, especially around the most common types of stars.

“I’m pretty confident that there are Earth-like planets everywhere,” Udry said in a Web-based news briefing from a conference in Portugal. “Nature doesn’t like a vacuum. If there is space to put a planet there, there will be a planet there.”