There are many terms from classic and modern SF that remain unresearched, and the Historical Dictionary of Science Fiction will be continually updated, especially as additional resources are put online. Boing Boing is syndicating new entries from the HDSF on a regular basis. (Read the series introduction.)
Pleasure Planet, Paradise Planet, and Hell Planet
In the real world, different locations can gain reputations, rightly or wrongly. Tahiti is beautiful; Las Vegas is Sin City. Of course, there are beautiful places in Vegas, and bad things happen in Papeete, but that's not how we think of these places. In science fiction, it makes sense that entire planets would be classified. We're adding three such designations today.
Sometimes these classifications are objective rather than subjective; while not everyone likes the beach, it's clear that a planet that humans can't survive on would not be considered a pleasant one. Thus our first new entry, hell planet, is the most straightforward. Mercury and Venus have both been referred to this way, and while some of our hell planets are penal colonies, or are inhabited by dangerous aliens, in most cases they're just really hot and have no atmosphere.
On the happier side of things, a paradise planet is also usually clear: it's a beautiful place, especially one that is naturally beautiful with a temperate climate. This is in accordance with the normal use of the term: "tropical paradise" is a cliché, but the Alps or the Rockies are rarely described as paradisical.
Our last entry in this grouping is pleasure planet, which has a different nuance. While these are also nice places to visit, the attractions are typically man- (or alien-) made, rather than natural. A vacation resort, in other words: sometimes (but not always) with implications of less-savory forms of recreation. While your choice between a paradise planet or a pleasure planet may be largely up to your own tastes, it's probably best to avoid the hell planets unless you're in it for the mining.
