langelgjm writes to mention that scientists are quite puzzled over the discovery of the largest planet yet. According to study-leader Georgi Mandushev it should theoretically not even be able to exist. 'Dubbed TrES-4, the planet is about 1.7 times the size of Jupiter and belongs to a small subclass of "puffy" planets that have extremely low densities. The finding will be detailed in an upcoming issue of Astrophysical Journal. [...] "TrES-4 is way bigger than it's supposed to be," Mandushev told Space.com. "For its mass, it should be much smaller. It basically should be about the size of Jupiter and instead it's almost twice as big." "TrES-4 appears to be something of a theoretical problem," said study team member Edward Dunham, also of the Lowell Observatory. "Problems are good, though, since we learn new things by solving them."'"