Exo-planetary discoveries abound in current popular and technical astronomical literature. Authors throw around terms like "hot Jupiters," "ice giants," and "brown dwarfs," (of course, the fantasy lovers among us imagine something quite different when we read the latter two terms), often assuming their readers (a) have read articles in which those and many other, related terms were defined; and (b) remember those definitions. With the number and types of newly-discovered planets circling stars other than the Sun increasing in leaps and bounds, how is an interested lay person to keep them all straight?
The wonderful astronomy website, Universe Today: Space and Astronomy News. They've put together a primer on "gas giant" planets that's straightforward and easy to follow.
Like all things astronomical in nature, gas giants are diverse, complex, and immensely fascinating. Between missions that seek to examine the gas giants of our Solar System directly to increasingly sophisticated surveys of distant planets, our knowledge of these mysterious objects continues to grow. And with that, so is our understanding of how star systems form and evolve.
Beginning with the difference between rocky (terrestrial) planets and gas giants (a term, by the way, coined by science fiction author) James Blish, the article takes you through the classification of various giant planets as they is currently understood, often giving historical perspective for those of us wrestling with the discrepancies between what we learned a decade (or more -- the term "gas giant" has been around since the early 1950s!) and what we read in the science news today.
Highly recommended as background for the general science reader and a resource for science and science fiction writers!