Exploring Planetary Mass - NYTimes.com An artist's interpretation of KOI-314c. C. Pulliam and D. Aguilar A newly discovered planet weighs the same as Earth but is 60 percent larger in diameter. That means the planet, KOI-314c - shown in an artist's conception - has a very thick, gaseous atmosphere. To determine its weight, astronomers used a method called transit-timing variation: They measured how long it took the planet to orbit its star and how that time was affected by its gravitational pull toward another planet.