The planets have been there for a long time, but NASA scientists have now confirmed the existence of 715 more planets outside our solar system using the planet-seeking Kepler telescope. That's almost double the number that was previously known.
All the new exoplanets -- what planets outside our solar system are called -- are in systems like ours where multiple planets circle a star. The 715 planets came from looking at just 305 stars.
Four of those planets are in what are known as "habitable zones," where it is neither too hot nor too cold for liquid water, which is crucial to the existence of life.
The four new habitable zone planets are all 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.
The Associated Press contributed to this report.