The Magic School Bus Lost in the Solar System their moons (Io for Jupiter, Mimas for Saturn, Miranda for Uranus and Triton for Neptune.) Once on a planet, the user can exit the bus, where a strange satellite called the "whatsit" must be clicked on to bring up an arcade-styled game in which the user, controlling one of the students, must collect one of Ms. Frizzle's tokens (giant coins with Ms. Frizzle's face on them) which provide the user with a clue as to the Friz's whereabouts and activate the "Friz-finder." There are only three clues available, but tokens will still need to be collected to activate the "Friz-finder"
Double planet the four, small, outer satellites of Pluto. A now-abandoned hypothesis for the origin of the Moon was actually called the "double-planet hypothesis"; the idea was that the Earth and the Moon formed in the same region of the solar system's proto-planetary disk, forming a system under gravitational interaction. This idea, too, is a problematic condition for defining two bodies as "double planets" because planets can "capture" moons through gravitational interaction. For example, the moons of Mars (Phobos and Deimos) are thought to be asteroids captured long ago by Mars. Such a weak definition would also deem Neptune-Triton a double planet,