dougettinger wrote:
How can extrasolar planets as large or larger than Jupiter possibly orbit inside an orbit comparable to Mercury's orbit around their parent star ? Would not the gases and ices have boiled away in a very short period of time ?
Planets don't really lose their atmospheres because they are hot;
Venus is much hotter than the Earth but it has plenty of atmosphere.
Planets lose their atmospheres because they are small like Mars.
The escape velocity of Jupiter is 5.3 times that of earth which
means that a Jupiter sized planet can be 5.3
2 times hotter (~ 7000 K)
than an Earth sized planet and still maintain its atmosphere as well.