The impeller made out of cast material in many cases may be called rotor, also. It is cheaper to cast the radial impeller right in the support it is fitted on, which is put in motion by the gearbox from an electric motor, combustion engine or by steam driven turbine.
Earth remains the only known planet to host life, due to a unique combination of factors. However, continued monitoring of alien worlds might one day change that, by finding other planets that share these attributes or by discovering other ways that life has found to blossom in the universe.
While this may be the case, these two planets are different in a number of ways. One main difference is the surface temperature between the two planets. The surface temperature on the planet Earth goes only to about 100 degrees Fahrenheit, which makes it possible for life to thrive on this planet.