an EGP can cool within gigayears to assume the aspect of our Jovian planets. Hence, by chemistry, clouds, and , the study of brown dwarfs and EGPs are inextricably linked.

Finally, the best theoretical fits to Saturn’s internal structure suggest that it contains a 5–20 Earth-mass core of heavy elements[@saumon]. This core of (perhaps) ice and rock may have been the nucleus around which Saturn formed and resembles the ice giants Neptune and Uranus. The latter may be aborted giant planets that were able to accrete but little hydrogen from the protosolar/protoplanetary nebula. The Neptune-mass extrasolar planet, 55 Cancri e, may be a stripped or aborted EGP. An alternative mode of giant planet formation is by direct collapse[@boss]. Under such a scenario, one would expect a closer correspondence between the heavy-element abundances of planet and parent star. Hence, the composition of its atmosphere and its heavy-element-dependent radius might be keys to an EGP’s formation. These are in principle measureable.

> [**Box: Brown Dwarfs**]{}
>
> Brown dwarfs are substellar-mass objects (SMOs) ( [0.07]{} solar masses $\equiv$$\sim$75 ) that are unable to ignite light hydrogen stably to become a star, but are otherwise formed like stars. The radiative surface losses of 