Radial velocity Radial velocity The radial velocity of an object with respect to a given point is the rate of change of the distance between the object and the point. That is, the radial velocity is the component of the object's velocity that points in the direction of the radius connecting the object and the point. In astronomy, the point is usually taken to be the observer on Earth, so the radial velocity then denotes the speed with which the object moves away from or approaches the Earth. In astronomy, radial velocity is often measured to the first order of approximation by
What Is to Be Done? What Is to Be Done? What Is To Be Done? Burning Questions of Our Movement () is a political pamphlet written by the Russian revolutionary Vladimir Lenin (credited as N. Lenin) in 1901 and published in 1902. Lenin said that the article represented "a skeleton plan to be developed in greater detail in a pamphlet now in preparation for print". Its title is inspired by the novel of the same name by the 19th century Russian revolutionary Nikolai Chernyshevsky. In "What Is to Be Done?", Lenin argues that the working class will not spontaneously become political simply by fighting economic