The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets (Mercury and Venus) whose epicycle remained collinear with the Earth and Sun, compared to the 'superior' planets (Mars, Jupiter, and Saturn) that did not.
In the 16th century, the terms were modified by Copernicus, who rejected Ptolemy's geocentric model, to distinguish a planet's orbit's size in relation to the Earth's.
- "Inferior planet" is used in reference to Mercury and Venus, which are closer to the Sun than the Earth is.
- "Superior planet" is used in reference to Mars, Jupiter, Saturn, (and later additions Uranus and Neptune), which are farther from the Sun than the Earth is.
The terms are sometimes used more generally: for instance, the Earth is an inferior planet as seen from Mars.
This classification is different from the terms inner and outer planet, which designate those planets which lie inside the asteroid belt and those that lie outside it, respectively. "Inferior planet" is also very different to minor planet or dwarf planet.
Famous quotes containing the words inferior and, inferior, superior and/or planets:
“The rights of citizenship will be taken away from all Jews and other non-Aryans. They are inferior and therefore enemies of the state. It is the duty of all true Aryans to hate and despise them.”
—Charlie Chaplin (1889–1977)
“Helpless, unknown, and unremembered, most human beings, however sensitive, idealistic, intelligent, go through life as passengers rather than chauffeurs. Although we may pretend that it is the chauffeur who is the social inferior ... most of us, like Toad of Toad Hall, would not mind a turn at the wheel ourselves.”
—Ralph Harper (b. 1915)
“I consider women a great deal superior to men. Men are physically strong, but women are morally better.... It is woman who keeps the world in balance.”
—Mrs. Chalkstone, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 2, ch. 16, by Elizabeth Cady Stanton, Susan B. Anthony, and Matilda Joslyn Gage (1882)
“Perhaps when distant people on other planets pick up some wave-length of ours all they hear is a continuous scream.”
—Iris Murdoch (b. 1919)