Atmosphere of Earth (see the temperature section, below). Because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. From highest to lowest, the five main layers are: The exosphere is the outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere). It extends from the exobase, which is located at
What Is This Thing Called Love? (short story) other, and wind up engaging in reproductive activities after all. What Is This Thing Called Love? (short story) "What Is This Thing Called Love?" is a science fiction short story by Isaac Asimov. The story was requested by Cele Goldsmith Lalli, editor of "Amazing Stories", as a satire of an article in "Playboy" called "Girls of the Slime God" which had suggested that pulp science fiction stories were concerned with aliens and sex. The story appeared in the March 1961 issue of "Amazing" as "Playboy and the Slime God", but Asimov later retitled it "What Is This Thing Called Love?"