Yesterday NASA announced a truly sensational discovery because 715 new exoplanets were found. These are the results of a new type of analysis performed on the data collected during the first two years of observations by the Kepler space telescope. This new method allowed to confirm that 305 stars have a multiple-planet system. So far, almost 1,000 planets were confirmed therefore confirming other 715 at once is a huge leap forward in the search for exoplanets.

The search for exoplanets has been going on for about twenty years but so far it’s been a really long and complicated work. That’s because every single star had to be examined individually to try to identify possible traces of a planet. However, the vast experience accumulated over the years allowed to create a new method of statistical analysis that can be applied to many planets at the same time when they are found in systems with multiple planets.

A team of researchers led by Jack Lissauer, a planetary scientist at NASA’s Ames Research Center, analyzed stars with more than one potential planet among the candidates discovered during the first two years of the Kepler mission, between May 2009 and March 2011.

This technique has been called verification by multiplicity and has a statistical basis. Of the 150,000 stars observed by the Kepler space telescope, several thousand have revealed candidate planets. Among these, several hundred have multiple candidates. These are objects that pass in front of a star so we can assume that they’re planets. That’s because if those were stars there couldn’t be a gravitational stable configuration therefore those must be planets.

Almost 95% of the 715 confirmed planets with this statistical technique are smaller than Neptune. This is very interesting because in the past mostly gas giants often larger than Jupiter were discovered. Four of the new planets found have a size of less than 2.5 times the Earth and their orbits are in the habitable zone of their stars, the one in which the temperature on the surface might be suitable to host liquid water.

Among the most interesting planets there’s Kepler-296f, which has a size that is about twice the Earth. It orbits a star that has a size half the Sun. The characteristics of this planet have yet to be studied to understand whether it has oceans of water or it’s more like Neptune, with a very thick layer of hydrogen and helium.

This new method of finding multiple planet systems will allow to find many more because there’s still an enormous amount of data to be analyzed. This will allow us to understand much better whether our solar system is an anomaly or multiple planet systems are normal and how many have planets in their habitable zone.

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