McCarthyism (named after US Senator Joseph McCarthy) was the practice of making accusations of treason without having the evidence to support it. This period was known as The Red Scare and lasted from the late 1940's through the 1950s.
A planet is a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and has cleared the neighbourhood around its orbit.