Earth-sized planets located about where Earth orbits the sun would take 365 days to circle their parent star. Those located closer, in Mercury-like 88-day orbits, transit more frequently.
Scientists need at least two and preferably three or more cycles to determine whether an apparent transit is real or some other phenomena.
“In order to catch several transits of an Earth analog, you have to wait for one more year to get another transit. It’s simply too early to call,” said astronomer Francois Fressin, with the Harvard-Smithsonian Center for Astrophysics.
The Kepler roster also boosts the number of multi-planet systems. Of the 2,740 objects, 299 are in dual-planet systems, 112 are in triplets, 44 are part of four-planet systems, 11 systems have five planets and one system has six planets.