An impeller (also written as impellor or impellar) is a rotor used to increase (or decrease in case of turbines) the pressure and flow of a fluid. An impeller for a dam turbine generator.
The smallest planet in the Solar System is Mercury (the biggest planet is Jupiter). For the longest time, the smallest planet was considered to be Pluto, but now Pluto isnât a planet any more, so weâre back to Mercury.Mercury measures 4879 km along its equator.Just for comparison, Earth is 12,742 km across.So Mercury is only 38% the diameter of Earth.or the longest time, the smallest planet was considered to be Pluto, but now Pluto isnât a planet any more, so weâre back to Mercury. Mercury measures 4879 km along its equator. Just for comparison, Earth is 12,742 km across.
1 Ceres accounts for one third of the mass in the asteroid belt. Despite this it is still the smallest and least massive of the dwarf planets.  For roughly the first 50 years after its discovery Ceres was frequently referred to as a planet.