This artist conception depicts multiple-transiting planet systems, stars with more than one planet. The Kepler telescope nearly doubled the number of planets scientists have discovered in the galaxy. (NASA illustration/Associated Press)

Our galaxy is looking far more crowded and hospitable. NASA last week confirmed a bonanza of 715 newly discovered planets outside our solar system.

Scientists using the planet-hunting Kepler telescope pushed the number of planets discovered in the galaxy to about 1,700. Twenty years ago, astronomers had not found any planets circling stars other than the ones revolving around our sun.

“We almost doubled just today the number of planets known to humanity,” NASA planetary scientist Jack Lissauer said in a Wednesday teleconference.

Astronomers used a new confirmation technique to come up with the largest single announcement of a batch of exoplanets — what planets outside our solar system are called.

While Wednesday’s announcements were about big numbers, they also were about the possibility of life connected to those big numbers.

All the new planets are in systems like ours, where multiple planets circle a star. The 715 planets came from looking at just 305 stars. They were nearly all in size closer to Earth than to gigantic Jupiter.

Four of those new exoplanets orbit their stars in “habitable zones,” where it is not too hot and not too cold for liquid water, which is crucial for life to exist.

Douglas Hudgins, a NASA exoplanet scientist, called Wednesday’s announcement a major step toward Kepler’s ultimate goal: “finding Earth 2.0.”

The four new habitable-zone planets are at least twice as big as Earth, so that makes them more likely to be gas planets instead of rocky ones like Earth — and less likely to harbor life.

Astronomers expect to find more exoplanets when they look at more data from the now-malfunctioning telescope.

— Associated Press