An unusual division offers Mercury and Venus in HOT PLANETS (0778737357), Jupiter and Saturn in MIGHTY MEGAPLANETS (0778737373), Pluto and beyond in ICE DWARFS
(0778737365) and Neptune and Uranus in GAS GIANTS (0778737349), comparing the properties of similar planets in our solar system and providing vivid, eye-catching covers and color photos throughout in these whirlwind tours of our solar system.
You have the four rocky planets, including the Earth, the gas giants like Jupiter and Saturn, and then you've got ice dwarfs
which would include Pluto and other large Kuiper Belt objects.
STern, Levision and other researchers calculate that the vast majority of the ice dwarfs would probably inhabit the Oort cloud, the more distant of the two sites.
Scanning the heavens with highly sensitive, widefield infrared telescopes should prove more fruitful, says Levison, because the ice dwarfs would reflect heat (infrared energy) more readily than visible light.
Stern calculates that a few of the ice dwarfs formed between Uranus and Neptune might have been ejected by gravity into the inner solar system.
A thorough examination of these disks, including their size and density, may one day indicate whether they contain ice dwarfs.
Stern's model suggest Pluto and its satellite Charon may in fact represent rare fossils: ice dwarfs no different from some 1,000 or so others in the solar system, except for their placement -- a dynamical niche much nearer the sun.
Several observational techniques, some more promising than others, might reveal an ice dwarf lurking here, he says.