NASA’s Kepler mission has discovered 11 new planetary systems hosting 26 extrasolar planets.

According to NASA’s Jet Propulsion Laboratory, these planets range in size from 1.5 times the radius of Earth to giants larger than Jupiter. All of them are closer to their host star than Venus is to our Sun.

Fifteen planets are between Earth and Neptune in size. Further observations should help determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune.

“Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky,” said Dr. Doug Hudgins, a scientist at NASA Headquarters in Washington. “Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits.”

Each of the newly confirmed planetary systems was called from Kepler-23 to Kepler-33.

“Confirming that the small decrease in the star’s brightness is due to a planet requires additional observations and time-consuming analysis,” said Dr. Eric Ford, a lead author on the paper confirming Kepler-23 and Kepler-24, and an Associate Professor of Astronomy at the University of Florida. “We verified these planets using new techniques that dramatically accelerated their discovery.”

The paper describing Kepler-23 and Kepler-24 will be published in the Astrophysical Journal.

Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33 contain a pair of planets where the inner planet orbits the star twice during each orbit of the outer planet, while Kepler-23, Kepler-24, Kepler-28 and Kepler-32 contain a pairing where the outer planet circles the star twice for every three times the inner planet orbits its star.

The confirmation of four planetary systems Kepler-25, Kepler-26, Kepler-27, and Kepler-28, containing eight planets and one additional planet candidate, will be published in the Monthly Notices of the Royal Astronomical Society.

“By precisely timing when each planet transits its star, Kepler detected the gravitational tug of the planets on each other, clinching the case for 10 of the newly announced planetary systems,” said Dr. Daniel Fabrycky, Hubble Fellow at the University of California and a lead author on the paper confirming Kepler-29, 30, 31 and 32.

The paper on the discovery of Kepler-29, 30, 31 and 32 planetary systems will appear in the Astrophysical Journal.

Kepler-33 hosts ﬁve transiting planets with periods ranging from 5.67 to 41 days. All of the planets are closer to their star than any planet is to our Sun.

“The approach used to verify the Kepler-33 planets shows the overall reliability is quite high,” said Dr. Jack Lissauer, a lead author on the paper on Kepler-33 and a planetary scientist at NASA Ames Research Center. “This is a validation by multiplicity.”

The confirmation of Kepler-33 will appear in the Astrophysical Journal.