London: A space probe has detected two giant Saturn-sized planets passing in front of the same star.
It is the first time that more than one planet has been discovered "transiting" a single star, according to NASA scientists.
The discovery of the two planets by space telescope Kepler is likely to provide scientists with vital clues about formation of planets and their interaction with others, a Daily Mail report quoting NASA said.
Kepler scientists have also identified what appears to be a third, much smaller possible planet around 1.5 times the Earth`s size but which is orbiting very close to the sun.
The planets were named Kepler 9b and 9c. The gravity of the planets acting upon one another means that their orbits are close to a 2-to-1 ratio, in what is known as a planetary resonance.
It is the first time this phenomenon of planets pushing and pulling each other out of orbit has been observed.
The discovery follows seven months of observations of more than 156,000 stars as part of an ongoing search for Earth-sized planets outside our solar system.
The observations show Kepler-9b is the larger of the two planets and both have masses similar to that of Saturn. Kepler-9b lies closest to the star with an orbit of about 19 days while Kepler-9c has an orbit of about 38 days.
Kepler, in its first year of operation, has already discovered around 700 planetary candidates or objects that could be planets.
"Kepler`s high quality data and round-the-clock coverage of transiting objects enable a whole host of unique measurements to be made of the parent stars and their planetary systems," said Doug Hudgins, Kepler programme scientist at NASA Headquarters in Washington.